What are the common causes of head shake / tank slapper?

[@karlhungus8946]

I've been watching a lot of motorcycle videos tonight and have heard a lot of BS from a lot of different self-proclaimed experts. It was nothing short of uplifting to come here and listen to someone who actually knows what he's talking about. Thanks for that!

[@catalystreactionsbw]

Thank you Karl - there's twenty years worth of work available via Dave Moss Tuning on line resources. Please help yourself so you can help others.

[@michaelsupple6081]

Karl...you took the words out of my mouth! That was so refreshing to hear.

[@cattwood3634]

I nearly died from a tank slapper under hard breaking at high speed several years ago AND I had never even HEARD of this and I took all the safety courses. Please pay attention, this video could save your life.Thank you for this EXCELLENT video, you speak the truth

[@catalystreactionsbw]

You can start on any bike to be honest - it is all a case of self discipline. A 600 is fine if you keep the revs below 10,000 and stay out of the power band which will keep you out of trouble.

[@catalystreactionsbw]

Steering dampers simply hide the source of the problem - maybe. Better to fix the chassis/suspension problem and then use the steering damper.

[@truthseeker8483]

I had put thinner fork oil to smooth out the ride..got a tank slapper ..so then added a hydraulic steering damper....I wish I knew about suspension sag setting back in those days..

[@topgopnik]

I agree 100%. The damper will only help when there is a road issue.

[@Bikeadelic]

Roads here in the uk are terrible. How do you feel about steering dampers as a sort of insurance and a confidence booster?

[@topgopnik]

@@Bikeadelic If the road is crap the dammper will help

[@Bikeadelic]

MXBoy thanks @Dave Moss Tuning do you agree?

[@christopherhawkins4521]

Great explanations. Good video to watch for all motorcyclists. I've only had one tank slapper and it is scary and surprising violent.

[@truthseeker8483]

"surprisingly violent" haha yes it is! My technique was to back off the throttle gently and hold the tank with my knees hard....

[@deborahchesser7375]

@@truthseeker8483 I had to snatch a wheelie to straighten it out on a Ducati hyper, scared the shit outta me

[@de2588]

​@deborahchesser7375 wheelie to get out of a tank slapper is genius and crazy lol. Safe riding mate.

[@catalystreactionsbw]

@BoomVision in measuring cirumferences, you can "see" what happened to your geometry. Sometimes it can be a big positive in chassis geometry,other times a negative. In general I say put the tires on, measure the circumference with a soft tape measure or piece of string and record the data. Ride and see how the bike handles. If it over steers raise the front end and lower it if it under steers. Dave Moss Host

[@sandrocorrea8435]

I have a low speed wobble and could never figure it out until you just explained it to me thru your video. never really scared me but didn't understand why it was happening but after you explained that your suspension has a lot to do with the wobbles it makes total sense thanks for clearing up my mystery!!!

[@catalystreactionsbw]

Hi Sandro. Thanks for watching and glad the content created a solution for you to an issue that was very difficult to resolve.

[@catalystreactionsbw]

really light front end is a geometry issue based on poor sag settings along with incorrect hyrdraulic settings for compression and rebound. This can be amplified by changing brands of tire and not correcting chassis geometry due to circumference changes.

[@catalystreactionsbw]

Let me know if you need help on settings etc. Once set correctly, the bike will behave differently, and you need to know what changed so that you can understand why the bike handles better!

[@catalystreactionsbw]

@BoomVision if you increased the sidewall size to a 70, the tire might be bigger in circumference. If so, that would make a change to the chassis geometry simply by the tire diameter. If the tire is bigger, the bike may be harder to turn in. If you still have the wobble, put a zip tie on the chrome tube to measure travel. See if you are bottomed out. Dave Moss Host

[@catalystreactionsbw]

Survival reactions increase headshake action due to trying to stop it with a death grip (as you experienced). Causes:- front wheel landing off center, front end too tall adding to the deflection, possibly too soft or too stiff settings in the forks to amplify the impact.

[@mikenash4216]

Hi Dave, I totally understand the issues of a death grip. However, what is the best way of dealing with a tank slapper (other than riding to avoid one in the first place, and correct setup)? Cheers.

[@catalystreactionsbw]

@@mikenash4216 If it starts keep the throttle still and keep your grip on the bars comfortable to loose. A bike wants to go straight, so you need to let it wiggle to allow it to straighten out.

[@catalystreactionsbw]

Motorcyclist will be coming out with a complete review on the 636 in their next issue with all the settings in it with detailed work ups and data tables that I provided to them. OEM settings are installed and are for you to sort out via professionals like myself. How urgently would you like the settings?

[@random04_]

Don't wanna jinx it, but I have a 2023 Ninja 400. I've hit 134 indicated (bouncing off the rev limiter) a few times and speeds around that as well in the 1 year I've been riding Tx, USA highways aren't generally the nicest half of the time under construction. Haven't had any issues thus far (knock on prestine hard wood). Great bike, love it. It has taken care of me so much

[@EVOASSHOLE]

Just enough to lighten the front while gunning it and the having the front wheel skip left right because the back wheel is pushing it forward but the front wheel is not facing true forward. Its a good reminder that its not a video game. I remember after 10 years still exactly. But i stayed on

[@MrImarcus]

Wow, learned a lot from this one. Always finish these videos feeling a little wiser but quickly surround myself with more questions!

[@catalystreactionsbw]

@BoomVision tires may have the same size cast into the sidewall but they are all different circumferences. As tires are variable here and it happens under deceleration, my guess is the bike has too much weight on the front of the bike (bigger rear tire and/or smaller front tire). Dave Moss Host

[@PaulMEdwards]

I have a 2008 Buell 1125R and had a severe tank slapper last Thursday. Thought for sure I was going to die, but I was able to ride it out. Was riding full throttle 160+ MPH indicated and hit a big bump on the lip of an overpass. This video confirms my suspicion that my suspension settings being a bit too rigid for the crappy roads here along with excessive speed when hitting the bump likely caused the issue.

[@catalystreactionsbw]

A cable tie on the fork leg will tell you if the forks are too stiff Paul with a lot less risk to your life and your family having to dealing with your death.

[@PaulMEdwards]

Dave Moss Tuning yep, I'm planning to go over the suspension again today. I've watched several of your other videos to gain a better understanding of the mechanics and process involved... If I were up in the Bay Area, I'd just come in, but I'm in SoCal. Thank you for sharing your knowledge!

[@catalystreactionsbw]

watch the video on fork bottom out. That is the most important one. When you understand what you need to do, mark bottom out.

[@PaulMEdwards]

I adjusted my forks to be a bit softer and it helped a lot, but there is still a slight oscillation at high speed. I did observe that the right fork tube is a few hairs (less than ½mm) higher than the left in the triple tree. I'm going to adjust that to be even with the left and also have the front wheel checked... I need to ensure it's not bent and that it's as balanced as possible. I'll also have the wheel & steering head bearings checked.

[@catalystreactionsbw]

Before you start all of that work, add a little rebound to the forks clockwise then remove it if there's no change, and do the same to the shock. That might be the source. Also make sure the rear wheel is straight.

[@jeffreymrrs150]

I had a bad once but saved it. Mine was under power.i shifted to second 500 before red line and hit a dip as soon as the clutch came out. Put dents in my tank. Just poor road conditions. Plus didn't realize my forks were leaking and in return that made it bouncy in the front. Always a good idea to check your bike.

[@sanjsarpal8048]

Hi Dave , just seen your Clio on tank slappers ,the causes.. Thanks , I know where I was going wrong . Under hard acceleration ,I pushed the handlrbar ... I'll correct that now and thanks... Sanj.. UK

[@stevebee6265]

After checking things out more in depth i found out i had some loose spokes. I took it in and tried to have it trued. It was unsuccessful. Finally got a new rear wheel and everything is fine. Thanks for the help. Thought i should post this as a follow up, perhaps it will help someone else down the road.

[@NothingToYou]

That cleared some things up. Thank you for taking the time to upload!

[@catalystreactionsbw]

seems to me that the front is too loaded (wheel is trying to drive into the ground not along it), so raise the front end a lot or as much as you can. Check sag and compression settings as well. Did you go from 70 to a 60 series front tire, or go to a much larger rear tire? Dave Moss Host

[@catalystreactionsbw]

nice detective work - that took some real attention to detail!

[@taepic8168]

Just bought a newer bike came with lowering link have massive headshake, this dude nailed it.

[@catalystreactionsbw]

@BoomVision you can send your questions via this You Tube channel by all means. Dave Moss Host

[@Deagoni]

I started on a Yamaha R6 2007 about a year ago. Still loving my bike, and i do ride sportive. I don't get why people complain about that, I've had no issues at all. When i began to ride I kept my bike out of the power band the first few months, and learning how the R6 reacts to certain things.

[@catalystreactionsbw]

Theoretically if you were slightly off center at 120mph when you popped up, it might have an effect. I've never seen anyone randomly decide to go bolt upright at that speed to see what it does....

[@soliddiesel7]

I always learn something new and interesting from you Dave, I consider you my mentor.

[@olivierseurin1204]

1:45 wait, what reason would one have to add gas whilst moving up a gear? Seen as it's a smaller sprocket, it's logical to very temporarily reduce gas right?

[@catalystreactionsbw]

Headshake mostly appears under hard acceleration as the shock is too soft and fork rebound is to fast, rapidly transferring weight from the front to rear wheel. When riders pull the throttle back fast, that turns the wheel slightly if not done correctly (counter steering) , then the front wheel wants to go back to straight s the bars move side to side.

[@khyoon14]

Once again Dave with his expertise.

[@Mitchumthegreat]

Dude!@01:36 just happened to me on the the way home and I had to research why. I shifted almost at red-line (I was driving like an asshole I must admit) and I guess I was too aggressive when I got back on the throttle resulting in a small shake that scared the SHIT out of me. I just got new tires too so I thought it was incorrect balance or something but when I let go of the handle bars its straight as a arrow. This REALLY helped me figure out it was me and not the bike. Thank you so much from Pennsylvania :)

[@m1aws]

Absolutely. holding on tight induces a wobble in many bikes from upsetting its natural resonance rate. It also increases front tyre wear. going fast often places air pressure down onto to the front of the frame/front tyre, which often contributes.

[@catalystreactionsbw]

Normally at or close to redline you are past peak power and the bike is actually slowing down (so the forks compress) and when you grab another gear the forks violently extend. That extension creates the shake and then we grip the bars right away which amplifies the shake. If we had the confidence to let the bike straighten itself out and be loose with our hands, the actual shake would be very brief indeed. Dirt bike riding really helps in this regard.

[@m1aws]

Dave Moss Tuning Absolutely. Many of the best superbike riders are ex-dirt bike guys. One cannot fight a tank slapper. Letting off handlebar pressure works. So sad after all these years super bikes are basically no different than bicycles when there are better methods around..

[@crackerican69]

I had an incident leaving a parking lot in a rush to beat the pending rain storms. Got a little too heavy on the throttle pulling out and shifted into second at around 10K while still on a slight lean/turn and the front lifted slightly and when the front wheel made contact, my bars and bike were at a slight angle and immediately went into a wobble. A little less grip and a little twist of the throttle with a slight weight shift back and it corrected quickly and smoothly. I would occasionally ride on straight and smooth roads with no hands to periodically check the track of my bike and to check for any wobble and noticed a very tiny shimmy. Over time, it got progressively worse. Checked the top bolt at the gooseneck and it was about 1/4 off so I tightened and torqued to spec and that also fixed that problem.

[@crackerican69]

Mitchumthegreat also from PA. Where about are you? I'm a few outside Reading

[@clarkwilliams808]

almost went down today cuz of a tank slapper under acceleration, getting my suspensions tuned asap! thanks for all the info

[@leeninfxstb]

I wish i had this advice years ago while drag racing my Vrod Destroyer. I had 2 wobbles at 130mph as I went the finish line. When using the stock Goodyear slick it wouldn't wobble, but with that frigging Mickey Thompson slick it would do it everytime no matter what I tried. I believe i needed more weight just in front of the rear wheel, but I don't have a track nearby after its closing, money, or time to test my theory. That and internal skull temporal bone damage probably from the wrecks.

[@catalystreactionsbw]

If one set of tires worked, then there is a diameter difference to account for between the sets that positively affected geometry.

[@leeninfxstb]

​@catalystreactionsbw I always suspected the MT tire grew more lifting the rear but using low tire pressure made it too squishy and unstable. I was also only about 160 pounds/72kg so i didn't have enough ass to tame it. I ran 10psi in the Goodyear, and tried all sorts of different pressures with the MT. Nothing worked

[@leeninfxstb]

​@@catalystreactionsbw and what said makes so much sense too because with the rear being higher than normal with the MT tire, the front end get loaded more on deceleration

[@grabir01]

On my Harley 2005 XL1200c, I only get wobble above 90mph and deviate from a straight line. Under 80-90 in the canyons taking the turns canyon carving, it is great! Only above 80-90 on the straights and doing a turn. My Bandit 1200s with the Harris racing frame never ever does this at any speed although when doing over 150mph on a straight with this bike I have not gone into any turns at that speed. But 100-110 I do and it handles very well. Just my Harley starts to wobble at these speeds. Is it the frame design? Would the 1200 Roadster be the better choice for Canyon Carving? I love the riding position of the Custom Sportster and the Bandit. Harley having the most comfort of all.

[@catalystreactionsbw]

The wobble can be generated several ways - 1. Fork oil too thin and the forks constantly topping out especially at speed taking grip away from the front tyre. 2. Rear shock too hard or too stiff creating an up/down movement that can initiate the wobble. 3. Slightly worn tyres that become profiled based on generic road camber. 4. Body position being very rear biased so the balance point of the bike is too far back. You can change fork oil, change fork position to lower the front and experiment with tyre pressures.

[@Irishgixxer7]

I'm curious if you ever come to southern oregon I would love to have you make sure my bike is set for me.

[@catalystreactionsbw]

I have had many trips to Medford for 2 days and had great support. I will have to make time for another trip this year in the Fall.

[@rwanchu]

One very easy way i found out why i was getting so much head shake was using a go pro. I simply recorded myself from the front of the bike to see what it is. And it turned out that i was actually poping my head above the visor while still acceleration hard at high speeds, thats also a very good reason for headshake.

[@ZIMMAS1K]

im reading your comment & shaking my head .......oh the irony.......

[@bobgould99]

I had a steering wobble on a 1972 Moto Guzzi Ambassador 757. It could have been worse but I just backed off the throttle slowly & used 3 lanes to get out of the corner. It was on a new stretch of motorway & the road was deserted so I decided to see how fast it would go. I was flat out in top gear. The speedo was reading 118 mph. That was also the top speed claimed by the factory for that model. Apparently it was due to a combination of the thrust of the shaft drive coupled with the tyres I was using & it only occurred over 115 mph. I was aware of the issue when I bought the tyres but I thought I'll never be going that fast.

[@DRAKE5001]

what a great and informative video ! but I'm a little confused about what I should do in order to stop a tank slapper .. some say that the best way is to relax the arms and turn the throttle a little more , other are sure that you have to put more weight on the front wheel by letting the throttle go .

[@catalystreactionsbw]

There are two choices so slowly roll the throttle back while letting the bars slow down their movement or hold the handlebars with a firm grip to stop the movement. I have not as yet been able to stop head shake with adding more throttle.

[@standbyme6395]

some recommend laying down on the tank more. or if by a miracle you can pop a wheelie. ride it off into the sunset. just joking. maybe.

[@theeagle6823]

+Dave Moss Tuning i have.u have to lean out and accelarate works for me all the time.

[@vitamc8584]

Very well explained. Now I know there are variables that causes tank slappers.

[@Bikeadelic]

Wtf how did it take me so long to see this! When I first got my bike And started to get a feel for it i was rolling on the throttle harder and harder as you do when you build confidence. It wasn’t long before the front wheel started to come up and every dam time I’d get a little head shake and since then I’ve been paranoid and terrified of going into a full tank slapper and it has really held me back. Because I tried looking it up on youtube and google but all you get is “it’s caused when your steering is out of alignment with the rear wheel and a resonance is created when it moves from side to side....” blah blah which doesn’t actually tell you what you or your bike are doing to cause this! So glad I finally have an idea of what I can do to stop it from happening this will give me some serious confidence! I can think about how I’m moving the bars and how i need to change gear and how my bike should be set up. So god dam happy rn!

[@catalystreactionsbw]

Excellent. Share what you figured out so you can pay it forward and help others please!

[@Bikeadelic]

Dave Moss Tuning yes I will! I don’t know many motorcyclist though ☹️ I emailed you btw.

[@curseboy]

Last year I was getting tank slappers, some quite scary, on the front straight of buttonwillow (over those little bumps). Unbeknownst to me, I had managed to put the top triple just a little offset, and with aggressive acceleration and those little bumps, things would get lively anytime my pace got closer to 2:10. Finally figured it out, I've had no issues since earlier this year when I re-aligned my front forks and triples.

[@MrParker300]

Awesome thanks Sir. I now know that I change gears incorrectly. I will try and be smoother

[@SlickD217]

Makes a lot of sense. Thanks so much my bike is definitely setup at a strange angle. Definitely going to adjust my fork angle.

[@pritamghosh4643]

Do a video on complete suspension science. How to set compression damping and rebound for street and track conditions?

[@catalystreactionsbw]

Those are in the Total Access section and also in the DM Tuning App in the road, track and race sections

[@drasticthompson1995]

Mr. Dave you are the man. Do you ever come to the East Coast? I would love to have you set up my suspension, I think I did pretty good user your videos but you would know better then me.

[@ZeroBoostBuick]

I love my 2010 R6. No steering damper and it's always stable under all conditions. However... At the track on a long left hand turn, the bars start rocking a little when finishing the turn still hanging off the bike but not too much lean, maybe around 90 mph.

[@catalystreactionsbw]

Then your bike is out of balance via rebound damping. Plenty of video on that topic and how to get it right!

[@darkknight17]

Dave Moss is the Master Yoda of suspension tuning. Hahaha awesome video. Please come UK/London this year!!!

[@catalystreactionsbw]

I will be in Telford at the end of March. Are you signed up for that event with SSR suspension or is that too far? If it is, where are you in London? The last time I was there was at The Oval motorcycle repair facility where you can rent your own bench and tools. I'd be happy to go back there.

[@darkknight17]

Hi Dave, Thanks for your reply. Telford is sadly too far for me, however I know The Oval very well and I can get there. I am signed up to your FaceBook page, perhaps you could announce your UK and/or London visit? I'm wondering how many other followers/fans of your work would also be interested in suspension set-up from the master of suspension tuning? It might be a good revenue generator for your services. I was after a base set-up for my stock 2009 R1 suspension. Not sure if one bike alone is worth your while. Please let me know either way. King regards

[@paulhorvath9784]

Hi from Australia Dave,,,could you please do a brief video on a 2019 Gsxs 750z video regarding a basic tire pressure and suspension set up for a 200 lb guy / street use..Thank you Kindly..

[@catalystreactionsbw]

if we come across one that I can test ride, absolutely.

[@korbindallas1859]

Don’t know if you’ll reply on this old video but I’m looking to get a 636 that will just wobble in general

[@dumbcat]

i've also heard one cause can be improper alignment of the front and rear wheels, as has been known to happen on some harleys typically after work was done to the bike

[@catalystreactionsbw]

Absolutely. That is more common than people think.

[@richydresher4157]

Hey Dave! I asked a question in another video and you referred me to this video. Thanks! I also noticed when I rest my hands on the grips on the stock 04 n 06 636s my weight of my wrist leaning forward wants to throttle. Also a great tip was reaching for the brake made me want to throttle so your videos are life saving. Only one more question if you have time.. Should I add a steering damper to the older 636's on top of working on my own mistakes to be safer? Thanks again a million times!

[@catalystreactionsbw]

A steering damper hides a problem. Once the chassis s stable, I have no problems with steering dampers at all.

[@DLITINTHEHOUSE]

And then there are normal head shake situations, like when you’re exiting a corner on a track and it’s super bumpy. Being hard on the gas will lighten up the front end and increase the head shake. Right? Because that was happen this past weekend for me. It never got to be too much to where it wouldn’t stop when the track smoothed out. But that’s to be expected I’d imaging.

[@stevelehel3625]

Will pilling your chest up closer to the 3tree help in stopping certain slappers? Seen this guy ona Duc pull himself forward over the tank and the hebejebe's stopped. Or was this a coincidence? Also, I had a bad experience with them once at 120mph crossing lanes (82 Katana 1000). Was able to stop it at about 90mph by locking the front up for a split second as the tire swept from cocked and passed through straight ahead, killed it on the spot. Havent been more sired in my life! Squeezed the break and let go ASAP.

[@catalystreactionsbw]

The front moves due to loss of traction so yes, it can help sometimes.

[@Aint1S]

Man, I had always thought it was something to do with 145 MPH. I've had it coming up to and going back down through 145 MPH on fresh paved strip of straight. Just brutal at almost full lock to lock. Is there any other geometric patterns that could result in a specific number causing repeatable tank slappers at 145 MPH? I sold that bike years ago or I'd have gone to check my rpm at 145 to calculate the wavelength for the RPM. (no damper) I trust your sag input though, that's sound advice!

[@catalystreactionsbw]

That sounds like some form of resonance or harmonics where you can put it to a speed. My 1250 Bandit does the same thing at 45mph (+/-10mph) and no matter what I have done to it it wont stop:- tires, forks, head bearings, wheel bearings, frame checked etc. It has become a feature of the bike that has become unique to it. I could strip the entire bike and start over from scratch and might find it.

[@davetechme]

Hi Dave, I had a tank slapper on the freeway today on my 02 GSXR 600 doing about 70-75mph after I hit a huge pothole. I was riding a little stiff than normal (rusty, coming back from a crash) and the wobble just grew worse until I prepared to fly off, loosened up my arms, and it corrected itself. I also swapped the front end with inverted forks that are raised a little higher than I remember my standard forks being. What doing you think could be the culprit?

[@catalystreactionsbw]

looking to come back this year to Essex where I used t teach in September. 2013 for the season to work some track days and race weekends. It would appear that there are a lot of hoops to jump through in order to be able to work at tracks so I need to be very thorough in prep for a summer of tuning at home.

[@edmaluf]

Thanks for the video. Very useful. Quick question: I'm thinking about buying a brand new bike (Ninja 636). The question is: Do all (sport) bikes come with the suspension adjusted at the "safest level" or should I take a brand new bike to a "suspension specialist" to have it sorted to my height, weight, riding style, etc.? Thanks for your answer.

[@catalystreactionsbw]

Thank you for the follow up - never thought to ask about spokes........ Yes it will help a lot of riders!

[@TheNino82ns]

hi DaveI am having problems (high speed wobble) with my 2011 zx10r after going from 19 55 17 to 19 50 17 and after doing some research I came up with shimming the rear shock to get back to stock rear ride height.I installed a 12mm shim on rear shock and was wondering if that's enough or to much. Also would like to know what tire pressure u recommend for street hard riding.the bike was great with 190 55 17 and around 32 psi F/R.thank you in advanced

[@averyhates1498]

Would you say that if you were to rev at normal levels and shift at lower RPMs that you would not be in as much danger of a tank slapper?

[@AlexLopez-vx3cr]

I have an old ZX7R, not entirely related but sometimes it gets real bouncy out of nowhere. Like around 70-90mph I'll just be cruising on the road and it feels like I'm on a lowrider. I have to let off the gas and slow down, once it clears up I can easily go 110-140mph smoothly with no bounce at all. But every once in the while it just gets bouncy and the roads seem fine too. I try putting weight on the front, the rear, speeding up, downshifting. Only thing that seems to fix it is braking a lil bit and slowing down. Could the front forks be worn out or something? Its a real heavy bike, wheelies are supposed to destroy those front forks on this thing cause of the weight.

[@catalystreactionsbw]

Feel the tire with your hands along the circumference and across the width. Does it feel even or uneven? If uneven, rebound may be too fast and that can initiate the oscillation requiring you to slow down. It cannot be a tire carcass issue as it is only at one speed range.

[@edmaluf]

Thank you for your reply. It is not urgent at all. I am still thinking about the purchase. I'll wait for your review.

[@cenmike82]

Do u have a video on how change the fluid on factory damper thanks

[@catalystreactionsbw]

I do not have a video on that, so I will put that in the queue for March next year when I return to the States from the Southern Hemisphere.

[@motomehanicar459]

Dear Dave, I hope you will see this question and help me. I have searched across your videos which are awesome indeed and from which I leant a lot, but I have not seen a video in close look on how to adjust suspension. (Which bolt to screw for preload and which for damping, and also in the rear). I have old ZXR 750 H1, which is known for rock hard rear end, but mine feels slugish, and turns slow in the corners and rear end compresses too much when I sit on the bike, especially with a pillion. I am heavy rider though, 210 lbs. In my country (Montenegro) there is no good mechanic I can address to. Can you please show me what to do because bike feels too soft for me. I ride on the street only. Sincerely Yours, Mladen

[@Docbpa]

Great video! Do you have any insight on head shake on Harley Davidson Street Glides? I have had a 2009 and now a 2015 and they both wobble at higher speed sweeping turns and sometimes high speed (80+) on the highway. Please advise. Thx

[@catalystreactionsbw]

A lot of head shake can come from weight transfer going back to the shocks taking weight off the front tire. If your shocks are set soft, that might be the case especially with the torque of the engine. The other part may be the forks rebounding too fast as you accelerate. If this is a wobble at a set speed range, that might be pressure related with tires, or an alignment issue with the rear wheel.

[@14icbm]

Yes...don't get near 80 mph.Seriously.If you want sport/solid performance,ditch the Harleys.

[@kevincraig8257]

Has the steering head been checked I've owned a few Harley's ride them all day long at a hundred

[@martindekker8203]

Hey Dave great info I had a tank slapper ( speed wobbles) years ago (when I was in my early 20's) on my then Suzuki Katana 650 coming out of a lefthand corner and it scared the crap out of me. My question to you Dave is what's the best thing to do to get out of it. I know when your driving in a car with a caravan and or trailer and they start to swing side to side trying to jackknife you're suppose to increase speed to get the trailer or caravan back inline. But how do you get out of a speed wobble on a motorcycle? Cheers

[@catalystreactionsbw]

Two ways Martin. One is to very gently roll off the throttle and let the bike sort itself out while you keep bar movement limited. The second is the same of adding throttle to unweight the front slightly reducing or even eliminating the wobble. On the race track I have only managed to succeed with increased speed twice with the front wheel losing grip and the wobble ceasing. More often the slight reduction of speed has created a quicker resolution with less risk.

[@REM44MAG]

I'm not sure where I heard it, but I also heard sitting too upright at high speeds can cause tank slappers? Like lets say you're pinning the throttle in windy condition at like 120+mph & you get out of a tuck too early?

[@bandogbone3265]

Is a steering stabilizer of value as "insurance" to prevent tank slappers, or is it just a band-aid that covers up things wrong with the bike and with the rider's technique that remain dangerous if not fundamentally corrected?

[@catalystreactionsbw]

Once the chassis has been set perfectly, the stabilizer as a tool can do it's job correctly. Then you need to define your settings for steering via the adjuster it has. It cannot in any way be set so that you have to put more effort into steering.

[@antdx316]

There are different kinds of wobbles though. Those that wobble and wobble more and more and more w/ no end, those that constant wobble, those that wobble very quick and go away. Setting up your bike where it wobbles quick and go away like any new Superbike is the way. Any other wobble means the bike and the rider needs to be evaluated before they leave their own skin on the ground but some don't care. They think all wobbles are the same but they aren't.

[@BoomVision]

@CatalystReactionSBW Thanks for response, The front tire I acutally went up from a 65 to a 70. But I am slightly confused. After figuring out your circomfrence difference, you then take that data and go for a test ride to check for turn in/out and adjust ride hight using that? If you are simply adjusting the ride hight according to turn in, why do you need to calculate the circumfrence?... and finally, if I have the decel wobble from a heavy front end, how do I fix that?

[@Idoy10]

hey dave, does damaged steering head berings also can be a cause to those wobbles? and when you said that a bump in the road also can cause it, a big enough hit can damage something in the bike that would make it wobble in high speed (not just after the hit)? Thanks alot!

[@catalystreactionsbw]

if the head bearings are loose to start with a severe impact can flatten out the race sightly making the issue worse. Impacts can also bend wheels and damage wheel bearings.

[@steveman1982]

Speaking of tankslappers, what is the cause of the front brake pads to move away from the disc during a violent tankslapper? The interia of the pads and pistons suddenly coming to a stop and reversing direction? Or something else entirely?

[@catalystreactionsbw]

Inertia will always fling parts in an outward direction and as a tank slapper goes from side to side and pistons move, the pads hammer the pistons into the caliper hence the need to pump brakes

[@MrGhirbo]

Was the tank slapper under acceleration OR under deceleration OR cruising OR changing gear? 1)geometry of the bike is flawed bc sag is not set correctly. a)back of the bike is sitting low &front is sitting high, the front hits a bump& bc front is too stiff to flex off the bump, it causes the wheel to jump and land not in a straight line. b)back of the bike is too stiff & front is too soft. The front hits a bump, it lifts the front in the air. 2)under acceleration if people pull on the handlebar while going 100% acceleration 3)compression&rebound are exactly overlapped 4)if you hit a severe bump and suspension bottomed out completely

[@paulcopeland6024]

Hi Dave you may not remember me but we played rugby together in south woodham

[@catalystreactionsbw]

Hi Paul. I do remember..... I remember Sunday mornings and breakfasts. There are many great memories from South Woodham in general, rugby and from teaching.

[@freelancerider100]

I am eager for this "national emergency" to be sorted out and we all are safe and healthy where the only personal protection include helmet and leathers- thanks for sharing your wisdom, it's much appreciated. Could you explain more about the hydraulic balance between com and tens? I notice when the compression setting is to soft that the bike gets more head shake at high speed- how do you tell if your rebound is too tight/slow? By tire wear? I'm referring to very fine tuning the 1/4 turn in or out... I get a heavy feeling from the front at 150+ almost like a brake or wheel bearing- I guess I can check it for heat after a good ride- maybe use a digital thermometer to compare one side rotor temp to the other? Bearings and such...

[@baneoffsight4871]

If you check his videos on rebound, his starting point is to push the suspension down and when it comes up again, it always bounces just once. As for compression, his starting point is to allow the suspension to travel 2/3 of the fork length. For me, I stopped tank slappers by reducing the spring load (pre-load) which allowed it to absorb as much of the energy when I go over a bump, but not too much that the steering feels heavy. As for the rebound I decreased it further to the point where it doesn't bounce when I push it down (i.e. it comes up faster), so that when I go over a bump, the suspension is ready for the next one. As for compression, I'm comfortable with it travelling 2/3 of the way under hard braking. All in all its the feel- whatever makes the bike feel safer and easier to handle. I always make tweaks here and there and feel the difference and if it feels off, I revert back to the default settings

[@catalystreactionsbw]

@rwanchu very resourceful!

[@stevebee6265]

I will also add, this happens while going in a straight line, more often and more intense going downhills, and decel. I do not trust my bike, its a scary ride... At 75mph the bars start turning, the rear tire wags back and fourth as much as 10"... i've checked everything i know to and feel like i'm chasing a ghost

[@Vidjeah24]

what does it mean if it starts wobbling at 70mph, on steady throttle (stock CRF250L). Moving forward on the seat seems to make it worse, unless I am really holding onto the tank

[@catalystreactionsbw]

If moving forward makes it worse, the fork travel is too far or forks are positioned too low.

[@BoomVision]

@CatalystReactionSBW Thank you for the response. My major problem I have found is ever since changing my tires out the bike has a slight handle bar wobble that it never had before. It seems to only happen during decel, any ideas?

[@m1aws]

Tank slappers are due to the bike being garbage. Its a combination of torsional resonance against its stiffness/sogginess. I've noticed wandering from gyroscopic induced torsion on rubbish swinging arms or forks to the slow or fast shimmy type wobbles where the headstock is attempting to rip itself off the frame. I've had a BMW R1100GS since 1995 and found it totally unable to upset because it is seriously stiff from end to end.

[@igorchak48]

I hit a tank slapper on my Ducati Monster 1100 Evo....fairly sure Ducati's are not rubbish...

I have a fjr 1300, and I have serious weave (not wobble or shimmy) at high speed. I checked all suspension settings and seems OK, Could it be that I am light and the back of the bike starts to fly at high speed (+130 mp/h) Thanks.

[@catalystreactionsbw]

If you have the stock shock it may be too soft creating the weave, so measure the bike with you on and off it using two fixed points. If you are 50mm or more the shock is too soft. If you are 25mm or less the shock is too stiff.kzbin.info/www/bejne/o3yWl5-BrctnZ7c

[@busakiller1117]

Hello sir I have a question for you. Last night God saved me from a Tank Slapper but luckily nothing happened not even a scratch on me or my bike. But now what are the things I should check in my bike as the bike is running perfectly like before but I'm still very concerned

[@kubastachu9860]

Dave, is there any chance you'll be visiting Europe with your crew? I have slight wobble/tank slapper issue with my bike and my mechanic told me he doesn't know what to look for, I can ride the bike regardless but I don't want to be surprised, and since I have watched your videos about adjusting the bike to rider I would not only like you to have a look at this issue but also help with all the adjustments, so that I could use the bike to its fullest. I haven't met any mechanic here in Poland who would have at least part of your expertise, while most riders tend to tell me I'm overcomplicating things when I replace brake fluid and I should twist the wrist more and put on aftermarket exhaust.

[@catalystreactionsbw]

Hi Kuba. That is something we can resolve quickly via Remote Tune. Can I get your email address please?

[@kubastachu9860]

@@catalystreactionsbw sent you a message

[@briangutierrez5635]

my question is my friend leaks coolant from his 2012 Yamaha R6 the drain out the old and put new coolant but it still leaks when he rides

[@catalystreactionsbw]

great to find a simple solution!

[@noaddiction3194]

I did a zx6r front end swap on my CF650NK, I found that I need to re-tighten the steering head very often, otherwise it will have steering wobble at high speed, not sure why..and after I tighten the bearing a couple of times it won't work anymore and have to change them.

[@catalystreactionsbw]

Are the bearing sizes for the races in the steering head the same size? It sounds as thought there is a difference and if they are loose, the ZX6R bearings may be smaller?

[@noaddiction3194]

Hmm..could be I'm running cfmoto bearing as cf650nk is a Chinese replica of er6n which share the same bearing P/N with ZX6R

[@Rohan-qr1zn]

Are lightweight naked bikes more prone to tankslappers compared to faired bikes of similar weight?

[@catalystreactionsbw]

Not at all. It all depends how the bike is set up from the Factory. Stiff forks and soft shock settings will assist in a tank slapper happening, hence the need to set the sag correctly when you get a new to you motorcycle.

[@Rohan-qr1zn]

@@catalystreactionsbw thankyou

[@SSDkoChan]

I thought speed wobble on a motorcycle was similar to that of a skateboard. The solution for skateboard speed wobble is to carve and not go fast in a straight line. Does the same apply to bikes?

[@Unfunny_Username_389]

no

[@tommygun6028]

Great show....

[@bobwalton9266]

You get a tank slapper when the natural frequency of the steering is the same as one of the natural frequencies of the the bike as a whole. One sets the other off.

[@catalystreactionsbw]

Dave Williams, editor, replying here. There are actually 2 causes. You're describing the "inherent" cause, one created by geometry then instigated by speed (speed wobbles). Harley's still suffer mightily from this. Poor geometry creates these "frequency" harmonics. Sportbike engineers dealt with it years ago because they wanted to race production bikes, but you can accidentally engineer yourself into that realm with incorrect geometry changes. It's tough, but can happen. The second and most common cause today is rider over-correction in response to a bump or pothole etc jarring/deflecting the front end. The bike's gyroscopics make an instantaneous correction, but then the rider, instinctive and late, makes one too (an additional one), thus an over correction. This process escalates until the rider is thrown or crashes the bike. If the rider is thrown the bike will straighten up in 2 oscillations and ghost until it hits something. If the rider eases their grip enough, which usually requires rolling off the throttle as a natural consequence, the bike will right itself in 2 oscillations and save the tank slapper. In reality the bike saves itself when the rider quits unwittingly screwing it up.

[@bobwalton9266]

The rider might sometimes be partly to blame for some tank slappers, but that's no excuse for designing something unstable.

[@ColinBell321]

Unstable means quicker reacting. For someone that has the skill to manage those qualities, it could be a better ride from their perspective. Obviously within reason. Most manufacturers aren't designing unstable motorcycles... unless you buy something North American made ;)

[@CP110]

@@ColinBell321 Buell 1190RX

[@Chevy1645]

I have an 07 Daytona 675 that tries to do a tank slapper under hard acceleration. No gear changing before and not near redline. The steering damper is preventing it from getting serious but it is very worrisome

[@catalystreactionsbw]

Here are some following causes for you to review:- rear tire too big, front fork too low. Rear tire pressure too high or too low. Fork rebound too fast or too slow.

[@Chevy1645]

Dave Moss Tuning thanks as far as tire size they are OEM recommended as well as tire pressure as per OEM recommendation of 34psi front and 36psi rear. As far as rebound and forks I will be taking it to a local shop and have them check it for me. The bike was laid down so I am worried the forks are damaged. I also discovered the rear tire was out of alignment 5 dots on one side 6 on the other. I corrected that seemed to help but not totally fix the problem.

[@catalystreactionsbw]

Take put the forks and loosen the nut on the upper triple clamp. Put one leg back in and secure it with the lower triple clamp bolts. Then try to fit the other leg, If you have to pull the upper triple clamp to get the fork in the lower (and possibly upper) is bent.

[@racermx775]

you have to adjust your Static Sag. I had same problem, until I tuned my Sag. now it is gone

[@alexpearson7693]

Any idea what would cause a vibration at 80mph? I low sided the bike and the wreck was super minor but ever since I have the vibration. I’ve inspected wheel bearing, rim, tire, brakes, forks, everything seems fine. The vibration is not serious but definitely unsettling when under acceleration. Any tips would be greatly appreciated!

[@catalystreactionsbw]

Have you checked the triple clamps are straight? Is the free leg square to the axle? Watch the video on how to mount the front wheel.

[@BoomVision]

Mr. Moss, what email is best to contact you with regards to questions? Thanks for all the hard work.

[@Outrageprovocateur]

So much crazy talk here. Wobble is something that occurs all the time in a bike. The bike tracks. When a stiff rider rides, he death grips the bars and through this stiffness the natural wobble is amplified. If he hits a big bump or the front gets light his tight grip amplifies the head shake. Dont listen to me go check out Keith code and just watch it all, there is a proper section on wobble there.

[@igorchak48]

Great video, good points but for some reason didn't mention a steering damper which will 85% of the time save you from a crash.

[@catalystreactionsbw]

Thanks for the comment, and yes, agreed! In this case and on all my bikes - I don't own a steering damper as I spend a lot of time sorting the chassis and suspension. As it is a tool, I want to use the tool for the right purpose, so I encourage everyone who wants one to use the tool correctly verses a pacifier or band aid.

[@maximilliancunningham6091]

Great presentation. Great voice, sounds like could be a game of thrones character,,,

[@aleksdamaco]

Is a harder or softer spring rate more prone to slapping

[@catalystreactionsbw]

All depends on the tension set on the spring. If less than 50% or 100% of travel is used, same end result.

[@fi8er1]

I have an R6 2016, will a steering damper really help me avoid this?

[@catalystreactionsbw]

I do not own a steering damper - never have on any motorcycle I have ridden - street or track. Steering dampers can hide a flawed chassis and band aid the issue rather than fix it. Once. a chassis is set, the steering damper can be used as a tool and needs to be set correctly.

[@jsallerson]

I think I blew a shock in my fork. Would that cause a tank slapper? The forks got very stiff during my last ride but I don’t think it’s a fork seal. I’m getting it under both acceleration and when hitting large bumps. Any ideas would help.

[@catalystreactionsbw]

Put a zip[ tie on the fork leg and see how much travel you are using. If less than 50%, that would be the cause.

[@two_wheel_zen]

What's the correct way to be on the throttle? Is it just being a bit looser with your hand?

[@catalystreactionsbw]

Yes, with enough tension to hold the grip that allows slow subtle movements. Tense grip creates a ratchet style movement and can be very jerky.

[@two_wheel_zen]

Thanks Dave!

[@user-jt6nw6wm5q]

hi, i started noticing some light headshaking on my gf's cbr250 while decelerating at around >90km/h. i checked everything (headbearings, front tires, suspension is not adjustable) could it be a misaligned rear wheel which forces the front wheel to turn while the geometry of the front tries to center it? thanks

[@catalystreactionsbw]

It can be rear wheel, it can be tire shape via wear, it can be bent triple clamps from a previous fall.

[@user-jt6nw6wm5q]

@@catalystreactionsbw thank you for your time! i am going to check this.

[@user-jt6nw6wm5q]

if anyone is having the same problem: the fork legs were crooked. I followed more or less the steps in this video from david moss: kzbin.info/www/bejne/p4XZlmqDad-Coqc The bike now not only stopped the wobble but feels much more planted, i am very happy with the outcome.

[@catalystreactionsbw]

@@user-jt6nw6wm5q Thank you very much for sharing the issue, work done and the end result. I wish more people would do this to inspire others!