Recumbent Trike Wheel Slip Test 20" vs 700c Wheels with The ICE VTX & Greenspeed GTO

We noticed that the 700c rear wheels on our ICE VTX's were slipping out on extreme grades so we decided to try the same grades with a Greenspeed GTO with a 20" rear wheel.

[@JaYoeNation]

Thanks for the video. I always rode fully loaded touring… it’s interesting to see you ride up so easily. In Korea I went up a incline on 20’s. But current TiFLYX seems pretty robust but the wheels have broken loose on a 17.

[@bikestrikesrazors]

In our last video where we were climbing Mt. Umhunum, with just a little gravel in the road, the 700 on my VTX was slipping with enough torque applied.

[@johnmoncrieff3034]

The fulcrum effect of the larger wheel and longer forks placing the CofG further from the rear wheel contact patch would have a greater effect than the difference in the contact patch size of the rubber compounds! The weight of the rider being the largest of all weights involved!

[@bikestrikesrazors]

Thanks very much for the information, John!

[@mostlyharmless1120]

I love your channel. I love side-by-side comparisons.

[@bikestrikesrazors]

Thanks, Mostly, and thanks very much for watching!

[@charlilangford3962]

The friction between the tyre and road is what you need to know - more friction means less slip. The variables are the stickiness of the tyre, the tyre pressure and the weight on the driven wheel. The contact patch increases with weight and reduces with tyre pressure. It shouldn't be affected much by wheel diameter; a smaller wheel has a shorter but fatter contact patch at same pressure. Basically the size of the contact patch is given by weight on the wheel divided by pressure, so if you have 50Kg weight on a wheel and tyre pressure of 4 Kg per sq cm (about 55 psi) your contact patch would be 50/4 - just over 12 sq cm (about 2 sq inches). This will be slightly modified by the stiffness of the tyre and how much it compresses because a longer thinner contact patch means the tyre deforms more as it contacts the ground (this greater deformation causes greater energy loss due to rolling resistance, which is why the racers are now moving towards fatter tyres). The weight carried by each wheel is proportional to the distance of the wheel from the trike's centre of gravity, so the ICE VTX with it's longer rear frame will have a greater proportion of its weight on the front wheels; adding this to that it's about 10 Kg lighter and you'd expect it to slip more. Heavy loaded panniers at the back increase grip; you could try the ICE with about 25Kg in panniers over the rear axle and the slip should then be similar with both trikes

[@bikestrikesrazors]

Thanks very much for the help, Charli!

[@mikejfranklin7000]

1. A great advert for trikes: no bicycle could do 20% grade! 2. How do you measure the area of the tyre contact patch? 3. The weight of the trike, and the weight and location of the rider's body will affect the downward force on the tyre contact patch and therefore the size of the patch and the friction.

[@bikestrikesrazors]

All great points, Mike! I'm not sure how you'd measure the contact patch size, as someone would have to be sitting on the trike to depress the tire to get an accurate measurement. Maybe charcoal the tire then ride over some white paper and measure the width of the mark. But then you'd only have the width and not the length. Might have to email a tire manufacturer and talk to one of their engineers. :)

[@tomiday66]

I've experienced a small amount of slippage on my stock Catrike 559 on climbs, but usually when there is a bit of dirt or gravel on the road. On clean surface, only on rare really steep sections. However, I also own a Catrike V3 fat tire with a Bfang motor and 4" tires. Slippage on unpaved grades is THE limiting factor with the fat tire trike. I rarely use the throttle, but have learned to take a hard run at an approaching steep section under peddle assist and then give it the gas at the first sign of a slip. That way I can often peel out all the way to the top like a dirt bike.

[@bikestrikesrazors]

I need to see video of one of those peel out's! :)

[@rogerbivins9144]

It'd be great if you could have access to a large enough scale to determine the percentage of weight from the front to the rear wheels on each trike. I'm pretty sure the real difference in traction is a result of the unequaled load distribution much more so than the size of the contact patch or diameter of the wheels. Still an interesting comparison and thank you for sharing. Cheers

[@bikestrikesrazors]

That would be an interesting analysis!

[@mikldude9376]

The science of traction :) , it would be interesting to throw some bathroom scales under the back wheel of each trike while you are sitting in it and see what the weight distribution is like , and it may even be interesting to check front to back to get a weight ratio on each trike. As an old car guy and ex trucky , axle weights and wheel bases are of interest to me .. I dont own a trike ( i would like one ) , but if i could buy one in my neck of the woods , i would be interested in those things .

[@bikestrikesrazors]

Interesting idea, Mikldude! I'll have to try that with the scale. Now I'm curious!

[@fernmoss3539]

Exactly ^

[@tobisteffen]

It's about the distance of the rear wheel/ground contact to the center of gravity of the whole human/bike weight. The further the rear wheel is located to the back, the more slipping, because a higher percentage of the weight rests on the front wheels which don't help in climbing.

[@bikestrikesrazors]

I agree completely, Tobi!

[@markfeldman6509]

Very interesting comparison. I have a Catrike Trail with 20” all the way around and a 559 with a 26” rear and 20” front. On flats the 559 is much faster with same cadence and gearing. Whenever I ride a route with climbs I always take the Trail. It is more compact, slightly shorter and puts my weight closer to the drive wheel. It is much more nimble and responsive through turns and much easier to climb with virtually no slippage. I can negotiate any grade without slippage. I prefer the 559 for my longer rides as the rider seat position is more comfy and the seat is a fine padded version as opposed to the Trail mesh seat. Also 559 as a very adjustable seat and the 559 is fixed. 559 much faster in general. For any hilly ride the Trail is the trike of choice,though.

[@bikestrikesrazors]

Hi Mark! Yep, my weight on the GTO is positioned right over that small rear wheel. The rear end of the VTX has always felt lightly weighted to me, which hasn't been a problem except for the steep grades. The VTX is without a doubt a much faster trike on the flats.

[@SuperSer886]

Hi! I try a lot of different tyres on my catrike speed, and yes, some of this cause wheel slip on steepest climbs or wet surface. On 20" rear wheel I try: 28mm Durano, good grip but very hard riding 35mm Kojak, very good handling but prone to flats 40mm tryker, good comfort and convert the trike to drift machine on wet rundabouts 50mm Schredda, fragile but awesome light, fast, comfortable and grip including offroad trails (discontinued). Is awesome the trike ability to climb high steep hills (>20%) with lows gear ratios withouth need to mantain balance at very low speed.

[@bikestrikesrazors]

Absolutely! I have Schreddas on my trike right now. Wish they weren’t discontinued!

[@andreashertting8545]

My catrike expedition is in snowy winter conditions at about 7% at the end, and so it cannot be used as a bike for winter in my region, and also it shouldn't be used offroad in ascending territory with gravel. I use a 26" Conti mountain-bike rear wheel and thick front wheels, but they slow down, compared to the original tires.

[@jeffreylines1535]

Between tire pressure, tire width you probably have 1/3rd more rubber on the road with the 20" wheel. I also think the tire compound between the Kojak and the Pro One are different giving favor to the Kojak for being a stickier tire (higher rolling resistance).

[@bikestrikesrazors]

I think you're likely correct!

[@Ltngdrvr]

Contact patch will be longer on the larger diameter tire/wheel, but narrower than the 20 with its wider tire. Would have been interesting if you weighed each wheel position with the rider in the seat to see the difference in load on the drive tire.

[@bikestrikesrazors]

Interesting! We'll try that next time! Thanks!

[@markrobinson891]

Another variable came to mind. Air pressure? I’m experimenting with 70-75 psi vs 100-110 with a recent move to tubeless. Can’t compare grip but comfort is obvious. I’m thinking that the adage high pressure=lower rolling resistance could be debunked.

[@bikestrikesrazors]

Hey, Mark! Yep, I bet that's playing a part. The 700c on the VTX is at 100psi and the 20" tire on the GTO is only at 70psi.

[@taiwan1895]

I don't think my knees could take that kind of punishment...

[@bikestrikesrazors]

Hey, Jim! Neither can mine, but it hurts less than riding into a moving propeller. :)

[@another3997]

Interesting video. As I recall, I've only ever had wheel slippage when riding my 2005 ICE QNT on grass, gravel or soil/mud, never on tarmac or paved surfaces. But gearing, how smoothly you pedal, plus the width, pressure, tread pattern and compound of the tyre, will make a huge difference on any given trike, no matter what size wheel.

[@bikestrikesrazors]

Indeed! Thanks, "A"!

[@ryancappo]

I thought you would see more slips at low speed om the ICE VTX than at high speed. I also had guessed that this test would have been to show the maximum incline until your tire always slips and the trike wants to roll backwards.

[@bikestrikesrazors]

Hi Ryan, and thanks for watching! I've been trying to think of a way to do that "maximum incline" test. I think you'd need to construct an adjustable ramp you could ride the trike up.

[@johnbarron4265]

Interesting test. I suspect that even when controlling for differences in the grip afforded by the rear tires, the VTX would still exhibit a greater propensity for wheelslip than the GTO, for two reasons: First, and most important, the 700c rear wheel is farther behind the rider's CoM than the 20" wheel, causing a measureable difference in rear weight bias and traction. Second, the 700c rear wheel forces the rider to pedal at a slower cadence in the lowest gear than a 20" rear wheel. The lower cadence means you can't rely quite as much on rotational momentum of the feet, pedals, and crankset to carry you through the dead spot of the pedal stroke, so you end up having to push harder during the middle of the stroke to regain lost momentum. These intermittent torque pulses are what cause the rear wheel to break traction.

[@bikestrikesrazors]

I think you're absolutely correct on all those points, John!

[@markrobinson891]

I’ve only encountered one hill among my regular routes with wheel slippage. (ICE SpritX w/700c) I might be more concerned about making sure brake pads are in good shape than wheel slip. Wheel slip=Inconvenient, slower until you find grip or alter your approach, uncomfortable. Brake failure=death/dismemberment.

[@bikestrikesrazors]

Hey, Mark! Yep, the slippage is really no big deal. I imagine you could find a grade steep enough that you couldn't get any traction at all, but who would want to ride up something like that anyway? Note: I'll see if I can find a grade like that for a future video. ) Funny you mentioned the brakes. I recently changed my disc brake pads on the VTX and not really knowing what I was doing, I was pretty terrified on the first few big descents. I kept imagining one of the pads would come loose and jam in a rotor at 40 mph. So far, so good! :)

[@electricstrider2665]

Nice...where’s Ma &Pauli? My fav was 4th of July ride...great stuff

[@bikestrikesrazors]

Hey, Strider! Mom's still riding, but she hasn't been out lately due to knee issues. Looks like she'll be getting a new knee soon, so we should be able to get her back out after that. Paul, I'm afraid, is a lost cause. No physical issues, just pure laziness- he'd rather sit on the couch and eat Cheetos than go out for a ride. I'll keep working on him, though! :)

[@donspeers5248]

I have a 20” wheel and I ride a lot on Gravel roads. I have had slippage on hills with gravel .

[@bikestrikesrazors]

Thanks for the information, Don!

[@gra6649]

I have an Ice eclipse and it’ll climb a tree on the bottom gear if I go slow enough.

[@bikestrikesrazors]

Sweet! We're planning on making a trip to San Francisco to test a few trikes on the steepest road in the city. It's supposed to have a forty-five percent grade. Should be interesting to see if we can make any progress against that. :)

[@waynesbutler7834]

I have the same tires on both my trikes , a 700c wheel with a 23c tire on my 700 and Kojaks on my Pocket and like already mentioned it comes down to contact patch and the sticky tires of the Kojaks . Although i am going to change the 23c tires to 25c tires not only for comfort but speed , there is a reason why pro cyclist have switched from 23 to 25c tires ..

[@bikestrikesrazors]

Hey! Yeah, I'm thinking of putting a 28mm on the back of the VTX for more grip and more comfort.

[@brenthalverson2372]

The size of the contact patch is irrelevant. Your two main factors will be how close your center of gravity is to the rear wheel. Lower tire pressure softens the tire which increases traction. Doubling a contact patch halves the downward pressure per square inch. These two factors cancel each other out.

[@bikestrikesrazors]

Thanks very much for the insight, Brent!

[@geraldwilliams8425]

Is it the fact that your weight is closer to the centre of the axle with the smaller wheel. But this is a problem that I have experienced a lot living in a hilly area as I do. I'm starting to wish that I'd gone for a 20''' rear. Great video

[@bikestrikesrazors]

Thanks much, Gerald! Yeah, there are so many variables, it's hard to tell what's making the most difference.

[@georgemccune5281]

The main factor for me when trying this is the compound of the rubber and it’s ability to conform to the roads granular surface

[@bikestrikesrazors]

Good point, George!

[@trikeyeah]

The only reason you slipped to me is because the VTX slipped in the dirt patches. On the Green Speed you were closer to the center of the trail so you didn’t drive over the dusty spots.

[@bikestrikesrazors]

You may be correct! We'll have to try going back to repeat the experiment and make sure the trail is clean. Thanks for watching!

[@shaunadamson4634]

On sealed surfaces (concrete or bitumen) with steep gradients maybe not quite 20% I have --never-- experienced slippage. Stats: Greenspeed Magnum XL, Schwalbe Big Apple 20" rear tyre, current rider weight: 150 kg (and falling thankfully). Unsealed surfaces - very different story. Anything approaching about 10% gradient and I'm loosing traction with almost every stroke of the pedal.

[@bikestrikesrazors]

Hey, Shaun! I’d think those Big Apples would have great traction, but I guess if it gets steep enough, even BA’s will slip!

[@albertbooth154]

I have a hp gekko fx26 I have never had that problem most of my problem just getting up the hill peddling

[@bikestrikesrazors]

That's a beautiful trike, Albert!

[@jfreeman6130]

If the problem was rear slippage, the only things that should have been compared is the tires.

[@bikestrikesrazors]

I’m sure the tires are making a big difference! Thanks for watching!

[@MishaDaBear]

The slipage was on a paved surface with debris on it, so it is dependant on hitting the debris. Please redo this on a cinder trail where traction is a real issue evan at lower grades.

[@bikestrikesrazors]

I'll give it a try! Thanks, Misha!

[@philllewis6916]

Yes, there was clearly a patch of sand or something, just where you detected the slippage!

[@bikestrikesrazors]

@@philllewis6916 We're going to re-visit this topic soon. Thanks for watching!

[@c.musard8712]

Simple physics ;) If all things are equal (same ground speed, same tack coefficient, same weight, same contact area), to transmit the same power (power = angular speed * torque) a 20" wheel will turn 38% faster with a 28% lower torque.

[@bikestrikesrazors]

Thanks very much for the information!

[@drawingart85]

I like cycleing & i have dream to have ice trike but it's just dream ^.^^.^

[@bikestrikesrazors]

Keep checking those local Craigslist ads. You may not find an ICE, but trikes do come up at bargain prices!

[@HaiderVlogs1111]

Price of gto?

[@bikestrikesrazors]

Hi! The closest thing in the current Greenspeed lineup might be the GT 20, which sells new for around $2650 usd. I always buy used and on the used market, a GTO would go for around $1500. Thanks for watching!

[@rubekker5572]

important to know is that a 20 inch Wheel can climb better than a 26 inch Wheel

[@bikestrikesrazors]

You're opening up a whole can of worms there, RU, but I will say that you "may" be correct. Certainly easier to get lower gearing with a 20" wheel. :)

[@richglaser4566]

The 700 wheel has less contact area. We all knew what would happen

[@bikestrikesrazors]

Thanks for watching, Rich!

[@andrewprint7523]

I only slip out on gravel and sand uphill. I ride a tiflyx so 3x 26x2.00 inch wheels. 😜

[@bikestrikesrazors]

Maybe I just need a TiFly! Good excuse to buy another trike. :)

[@andrewprint7523]

@@bikestrikesrazors If i would live closer, you could use mine for free to test it out. but i live in belgium so not really in handy 😉 but the tyflyx also got some other problems that you almost don't have whit the ice vtx or the gto20. 😉

[@bikestrikesrazors]

@@andrewprint7523 I've got a friend that lives in Belgium (Leuven), but he doesn't ride a trike :)

[@andrewprint7523]

@@bikestrikesrazors Nice i live at the belgium coast (Koksijde). 😉

[@user-ot6iq8wm5d]

มันคือรถลาดตระเวน เหมาะสำหรับกองทัพ

[@bikestrikesrazors]

Interesting idea! Thanks for watching!

[@ericscott4854]

Oh yeah? Change out rear cassette to 10spd with 50 tooth first gear (11-50 tooth), would probably fix the slipping problems with 700c wheel 🎡. lol 😂

[@bikestrikesrazors]

I bet you’re right, Eric! And it would make it much easier getting up that hill! :)

[@besley]

Interesting. Other than contact area I would want to know the comparative weight distributions of the two trikes. It sure looks as if the VTX rear is much more lightly weighted, which would of course give less traction. But get rid of that obnoxious intro you have at 0:23 - the quick cuts and loud noise almost made we quit watching.

[@bikestrikesrazors]

Hey, Besley- Yep, the VTX rear wheel always felt that it was lightly weighted, and I'm sure that has something to do with it. We've been meaning to update the intro, mainly because I think it was a bit too long. See what you think of the new intro (it'll be on the next video).

[@archertyro6481]

Rider weight distribution

[@bikestrikesrazors]

That's gonna have a big effect, Archer!

[@bobcatt2294]

The test is flawed - you do not test using a narrow tire verses a smaller wheel and a much wider tire.

[@someguy9520]

not that scientific. Diffrent tire types(at least same manufacture), diffrent tire widths, diffrent trikes, diffrent tires the kojak tires are utter dogshit IMO, they look fast but are in fact slower than some of Schwalbe touring tire offerings while being easy to puncture the Pro one is a proper summer road bike tire that has sufficient puncture resistance and rolls really efficient in theory, contact patch does not increase/decrease outright grip, the only thing that actually increases grip(and therefore rolling resistance) is the rubber compound. A wider tire but with the same compound might have a higher "chance" to not slip under high stress, but the main advantage is the increased tire life since there is simply more rubber to burn through My prediction is, that the 700c wheel is further back, away from the center of mass and does not have enough weight to press down and grip in very steep situations

[@bikestrikesrazors]

Thanks, Calvin! I never even considered how the rubber compound might effect things!