Motorcycle Wheelbase: The What, How, & Why of It

[@hstefan]

Love the fact that Dave casually flexes his RSV4 in this video. Tons of knowledge! Ride safe!

[@WasNotWas999]

I have no idea what Dave is on about... But I still love watching and trying to learn.

[@sergiocabrera458]

Hey Dave ,the last Weekend i upgrade my rear swigarm : paint , change bushes, clean everything ,new rear brake .Is a small bike but now runs like a new one.Thanks Dave and Team from Uruguay.

[@alexlau7115]

godlike as always. learnt lots. cheers

[@John-om5dm]

When's the DMT suspension course/series, sequential next one leading to the next, champ u business model

[@catalystreactionsbw]

When I get back from NZ March 8th, I will start mapping that out for filming. That should take about a week to plan all the steps and get all the equipment set. Once that is done, then it will be 30 minutes "classes" that will be posted to the DMT website for all members to access. Plan on one a week for several months along with several knowledge tests along the way. Some of those will be free on YT as much shorter and very condensed videos.

[@nickandtanya]

Great information and video as usual!!

[@ryanlowe2808]

Dave, you sir need to start a 2 day course, similar to YCRS for riding safer and faster, but only for learning your bike better and smarter! I believe if you don’t understand your equipment/machine, your more likely to fail because of it. I watch as many of your videos as possible, yet I’d pay to attend a hands-on instructional program from you!

[@catalystreactionsbw]

Hi Ryan. I used to tour the USA with Sportbike Track Time putting on the DMT suspension school doing exactly that. Unfortunately due to an incident with 4 wheels at a race event, insurance stopped the course as we would set up bikes and canopies in the hot pit. It would be great to start that again as I believe the course could be run with 3 stops per session. Two days would make that a lot easier to do.

[@ryanlowe2808]

@@catalystreactionsbw I did not know that! Very interested. Leave it to the insurance suits to make this sport less safe by trying to make it better? Statistics should counter that theory, and prove that your greatly reducing far more! I will definitely be on the watch for a new one should it ever occur again, thank you for all your knowledge and sharing!

[@paulboyce8537]

Nice video Dave. I just ordered progressive Wilbers springs and both valves for the front and Wilbers 641 shock for the rear with height adjustment. The plan is to get little more caster to the steering by changing the stock 190/50 rear to 200/55 (30mm higher tire) that will lift the rear by 15mm. The shock height adjustment is to compensate with front height correction to find a suitable result. The bike is ZX14 sports touring bike that I hope I can turn into more nibble weapon at the mountain roads that I have locally. You gave me more to think about with the rear wheel positioning that I haven't even realized. I like to keep the front on the bitumen and changing caster would also help on that but with the combination of a shorter wheelbase by 20mm might also be a factor in the overall combination of setup. I believe the full range of adjustment is about 70mm from shortest to longest. My local roads are lot of 20km/30km/40km/50km corners so very tight for a big bike. Goal is to make it turn and yet have a good compromise of keeping the front down. It has a pretty new chain so I think the adjustment is about at the middle now leaving about 35mm either way. So if I would take one link of the chain that would shorten the wheelbase about 20mm I guess. I have to confess I have no idea how big of a change this would be under acceleration. Combine this with the caster change. What sort of feeling would you have about the final setup? Am I completely wrong or is there a thought here that might work? Big fan of your videos. Learned a lot.

[@simoncrooks7441]

thanks for the interesting presentation

[@catalystreactionsbw]

Thank you for watching!

[@twowheelmando]

Thank you for this video.

[@victorgonza4528]

Great info Dave

[@karlogrady4907]

Cool video Dave. Question time: wont changing the angle of the swing arm cause the COG to change ? For the better or worse? For example if i put a longer shock on my bike, steepening the swing arm angle and raising the bike what sort of problems could that cause and how would you solve them ? Also another thing id like to ask, im putting a 750 engine into a 400 rolling chassis which has a steeper rake, swing arm angle snd a shorter wheel base than the original 750 chassis. Are there any problems or pointers you can suggest before i go too far as you mentioned in the video its a balance of been nimble and having a ‘horrible’ ride or a ‘slower’/lazy ride. Thank you

[@leadsled8961]

Drive sprocket to swing arm pivot angle /height could you talk about that please .

[@alanbrown5593]

Is there a correlation between the wheelbase v swinging arm length as a % ie better/worse.

[@RaulMarincas]

i'd love to see you make a series where you buy a cheap motorcycle and bring it back to life current year upgraded suspension brakes etc so we can understand the why behind the parts

[@brandonfontaine285]

Would need to be viewer funded. Sounds expensive.

[@thwinecone]

I think there is one. Called trash to treasure, with a gsxr 750.

[@KarloZg9000]

Thank you for another great video. The part at 10:22 confuses me, I thought that with a chain of the same number of links, this would result in a longer wheelbase in order to get the same slack. Lets say a +1 front and -3 rear, wouldn't the rear sprocket have a greater difference in circumference? When it comes to extreme anti-squat as in the wheel getting pulled under the bike, does it become unstable because of a shortened trail and wheelbase?

[@AirSKWolf]

Yes, Moss got a little confused there. The "usual" +1 on the front and -3 on the back results in a longer wheelbase if no chain links are removed. This is often not detrimental though because often people going for longer gearing are also riding highways and open roads more often where stability is welcome and nimbleness not usually required. Personally I did the +1/-3 on my Tenere 700 (yes, I don't use the bike for it's "indented" use) and I proposely didn't touch the chain links. I actually don't feel any difference to be honest though. Edit: I meant I didn't feel any different in handling, the gearing is very noticeably longer.

[@alangolightly9850]

Larger rear sprocket means more anti-squat. Close distance cs sprocket to swingarm pivot reduces varying chain tension as rear suspension moves.

[@ericteal]

16 RSV4 RF has longer swingarm with -5mm pivot position compared to earlier models with shorter swingarm at +2.5mm pivot position. Combine this with ever increasing rear tire size, what was Aprilia thinking? I'm looking forward to testing pivot positions this track season.

[@catalystreactionsbw]

With your excellent data tracking, record swing arm angle at rest as you change the pivot point and also track shock travel (no shock setting changes).

[@DarkIzo]

if i understand this correctly swingarm angle is primarily for the best outcome between squat and anti-squat when youre accelerating ? so thr angle is basically a function of known constants ?

[@theamalgamut8871]

Wheelbase: what about when we can move the wheel forward and backward? Should we consider the middle as the oficial wheelbase?

[@catalystreactionsbw]

The rear wheel is ideal in the middle two thirds of the slot. The rear tyre circumference is the issue as the it will increase or decrease leverage and that can change handling.

[@drewdemien481]

Hell yeah you should. Take and Trail are very important to the bike style, horsepower, and speed you'll want to travel for the safest riding possible. Like changing the Rake on the front end, you may need to extend the length of the shocks. I think that's right? Been a long time. Longer is more stable at high speed...?

[@arthur1418]

Awesome, thanks for this. You suggest changing spring rates depending on the swing-arm length you use in a given situation. Can a similar result be achieved by adding/removing preload in the shock?

[@catalystreactionsbw]

Correct - and also consider compression damping. Using settings will guide you to a softer or stiffer spring need.

[@RubberChickenMan007]

@@catalystreactionsbw I have a quick question. I have a Suzuki sv1000 where I installed a 2002 gsxr 1k front end. I'm having front end instability at speeds higher than 80 mph. Is there a way to correct for this? I installed a gpr damper and noticed it has slightly improved the problem but the problem still exists. Any recommendations?

[@catalystreactionsbw]

@@RubberChickenMan007 Check shock sag, then check shock travel used on the shock shaft. If bottomed out, stiffen the rear shock via preload and compression. If the shock oil is 5 years old or more, refresh it.

[@anonjohnnyG]

how does the ducati motogp bikes squat device play into this.

[@catalystreactionsbw]

It sets swingarm angle for optimal grip and electronics control wheel spin etc.

[@IvanGarcia-ug7mf]

brocks lowering rachetstraps kit for the front also works

[@vincentyap3188]

you mentioned 550mm to 575mm that is only 25mm or 2,5cm longer, i don't think so it affect a lot, in drag race they can go to 6 to 14 inches longer compare to stock

[@diesunddas93]

great video thank you from germoney !

[@IvanGarcia-ug7mf]

my swingarm length on my ninja 400 is 21inches , is that bad ? please n thanks DMT

[@dtacto]

Yeah. Unridable.

[@catalystreactionsbw]

For what purpose?

[@alotl1kevegas860]

First! Very informative video as usual 👍

[@Jodyrides]

The chain is its tightest, so that you can check chain slack, when you have the counter shaft, swingarm pivot, rear axle all on the same plane. Then rotate the rear wheel until you find the tightest point to adjust proper chain slack. also changing the gearing on a ninja 400-2018 through 2021, and the Z 400, to a 15 tooth,will trip an engine code and your gear position indicator will stop working because the onboard computer for the ABS sees that something is different in relationship between the transmission speeds and the wheel sensor speed for the ABS. The fix is start the bike let it idle for 30 seconds then ride for 10 minutes. repeat the idle/ride for 10 minutes ritual three times to get the check engine light to go out, and for the gear position indicator to start working again. I had this on my Z 400 when I went to a 15 in the front. About 40 miles later check engine light and gear position indicator stopped working. I went back to the 14 tooth countershaft sprocket, and I did the idle/ride/ritual three times, and everything started working again. I don’t know if the ritual Will make the computer and the gear position indicator start working again if I would’ve left the 15 tooth sprocket on. I can say this for the 15 two sprocket. The motor was not as smooth and it was not because I was lugging. Maybe it was the rubber damper on the counter shaft sprocket that came with the bike from the factory. The 15 two sprocket I bought did not have that rubber damper on it, and I did not like how it made the engine feel.. my machine how to Yoshimura slip on muffler on it when I bought it used with 1500 miles on it. I noticed that it had a slight hesitation just off idle.. I was able to buy a used perfect stock muffler which I installed on my Z 400, mostly because I do not hate my neighbors, and I do not want them to hate me. I am not 16 years old, so I don’t need a “hey look at me “exhaust system on my bike. with the stock exhaust muffler on the machine. The off idle slight hesitation is gone, but I had a vibration all of a sudden in the foot pegs and in the seat. To fix this I pulled the stainless cover off the back of the muffler, and I added 21 ounce stick on wheel weights to the wall inside the end of the muffler, then I replaced the stainless steel muffler cap. These weights changed The frequency that the muffler was responding to, and the vibration/buzz went away.. this trick of adding a stick on wheel weight also will smooth out mirrors that buzz and blur your vision of what’s following you at highway speed‘s. You just need to change the frequency that the mirror responds to by adding a weight. The weight I added was a 1/4 ounce stick on wheel weight. The mirror is clear now at highway speed‘s.. when I lube my chains, I have a long snorkel plastic bottle used for oiling furnaces. I filled it with 90 weight gear lube. I put my stand under whatever machine I am boiling the chain on so that I can rotate the wheel. And I put one drop of oil between the side plates on each link on the inside of the chain. that way, I don’t have a mess, and the oil must go through the chain before it flies off. This was a Honda bulletin/instruction in my owners manual when I bought my 1977 Honda CB 750 F. That’s how they said to lube the chain. One drop on each link on the left side and on the right side, between the plates. The chain on my 1977 Honda CB 750 what is the original chain when I sold the machine with 44,000 miles on it years later.. in this video you mentioned a buell motorcycle.. I was a motorcycle mechanic in the early 1970s at a Honda/Yamaha dealership. One of the other mechanics at that shop was eric buell. he worked there while he was going to pitt engineering school here in Pittsburgh PA USA.. Eric and I were at Summit point Road race track racing once.. we both had Yamaha TZ 250s. He ran over to my van and asked me if I had a spare ignition. I said yes. I gave it to him and he ran back to his machine to install my ignition on his bike. I went over to give him a hand, and when I examined his blown ignition rotor, I grabbed the rotor and it moved up and down. I yelled to eric frantically going through his toolbox in the van, your crankshaft is blown and it’s not the ignition. It was his outer main bearing which Allowed his rotor to contact his stator blowing his ignition..Always in a hurry

[@munter10]

great story.... carry on....

[@ferpk1549]

C'mon Dave, who you wanna fool? Your not being a great sketcher doesn't mean you ain't an artist! 🏍️

[@booger65man]

Dave, great explanation on length. After watching and learning I’m pretty handy with a welder and am considering cutting my swingarm in half and extending it a foot or two for more stability. Could you provide any recommendations whether I need 1 feet, 2 feet, or 3 feet of extension? Thanks!

[@raynic1173]

Wait a minute, I thought the whole purpose of the raked swing arm was to have tire want to crawl up under the bike, minimally of course. That's what prevents the sprung mass from squatting or collapsing onto the swing arm. Of course there's a sweet spot. With the chain tension on the top, it's pull basically horizontal and with swing raked it has to pull underneath. Getting the right amount is the key, balancing swing arm length, shock, HP, gearing...(???).

[@catalystreactionsbw]

100% correct, and us as humans make that perfect set up so elusive between swing arm angle, chain pull, rear axle location, shock length, spring rate and valving.

[@MrGhirbo]

if the swingarm angle is >9' , the problem is that bike wants to put the rear wheel under or forward of the bike. The bike wont handle at all at that point. ---> my guess is that it has too much antisquat ?!

[@catalystreactionsbw]

11-13 degrees is the ideal starting point with the tyres just kissing the ground. Newxt factor is how strong the valving and spring rate are, or how soft. Most of that is balanced against engine power and wheelbase length. If the rear wheel wants to go under the bike, then the shock is trying to lengthen so that would be anti- squat. Therefore the opposit is squat and finding that balance depends on far too many factors BUT, if you start at 9 degrees, you can use preload in the rear shock to test soft and hard and see how the bike behaves from 30-60% throttle.

[@duckbreaker]

Thank you for the paused English 'Aluminium' lol

[@RickyJr46]

Dave, the Gearing Commander website is super useful for this stuff. Find your bike in its database then input the changes you want to make for gearing, chain length, etc. It will crunch the numbers and show the new rear axle position, rpms, and the like. Try it, you'll like it: gearingcommander.com

[@Motosapien46]

The more of your videos I watch the more I see a motorcycle as acting like a helicopter. Everything you do affects everything else. It's a constant balancing act. Like a Yamaha engineer said in the movie Faster: "it's flying on the ground"

[@pawelwis7215]

Metric system 4 life :D

[@markcdeyoung3118]

I like my swingers short baby -1 nice en lively en agile en it keeps time PRECISELY at 5 minute till 12 0'clock WITHOUT MUCH ASKING FROM THE THROTTLE all day en every where I go my pig (BRP) she really SQUEALS nice now👍😆 you sound remarkabily like the guy from "they will kill you" chan. Especially your Intr0

[@George241312]

If someone really changed their gearing for better mpg might as well run the red light and head to oncoming traffic Jesus Christ,

[@okboomer1241]

I've done it. But what does Jesus Christ have to do any with it?

[@DarkIzo]

jesus christ is part of the oncoming traffic ?

[@ZuseTheYoungOG]

@@okboomer1241 he has the wheel

[@okboomer1241]

​@@ZuseTheYoungOG kzbin.info/www/bejne/a4uYp6uIa9Z8na8