My 29er wants to turn to the right, but my 20er does not. Why?

[fuxo]

Originally Posted by OneTrackMind

Was it a new uni? Maybe the previous owner biased the tyre with wear.
Or maybe the tyre is faulty.

Try putting the tyre the other way around on the rim.

What model is the tyre?

Unlikely to be wrong, but are the cranks exactly the same length?

The uni is new.
The cranks are the same length. At the beginning, that was my first though as that is the feeling: left crank seems shorter than right.
The tire is Kenda Karma L3R Pro, 29x2.2, 120 TPI casing. It seems ok to me, I also tried different pressures. Anyhow, as you say, I already have an appoinment to flip the tire in the repair shop, I will tell you soon how it goes.

[fuxo]

How come? I did flip the tire, finally. Now, it turns left. So the problem is the tire. But how is that possible? I don't see any defect and the job was done by a professional, not me...

[OneTrackMind]

Originally Posted by fuxo

The tire is Kenda Karma L3R Pro, 29x2.2, 120 TPI casing.

The Karma has a dual compound construction with harder rubber in the middle and softer on the sides. Maybe something went wrong during manufacture and the transition knobs are softer on one side than the other?

Did it do this right from the first ride? Or could it have developed from wear on a cambered road?

Or maybe it did something bad in a past life.

[Canapin]

Hi fuxo, what have you done about this issue since? Changed your tire?

I changed my offroad tire for a road tire and it cambers to the left.
I switched back to my offroad tire and I don't have this issue anymore. I need to do like you did, by putting the road tire front to back and see if it cambers to the other side.

My new tire is a SUPERMOTOX 27.5 X 2.4

[fuxo]

Hello again, I wished to write a reply weeks ago, but since then, the situation is even more confusing for me... changing the tire solved the problem in the first tests, but after some time, the problem came back... or maybe I did not notice it at first... or it appears from time to time... well, I don't know what to do.

A few days ago I realized that there is some play between cranks and hub when I loosen the cranks' bolts, so I can tighten them again with the cranks in slightly different possitions. It is less than two degrees I would say... don't know if it has something to do. I will try to test this next week.

[JimT]

Originally Posted by OneTrackMind

The Karma has a dual compound construction with harder rubber in the middle and softer on the sides. Maybe something went wrong during manufacture and the transition knobs are softer on one side than the other?

Originally Posted by fuxo

Hello again, I wished to write a reply weeks ago, but since then, the situation is even more confusing for me... changing the tire solved the problem in the first tests, but after some time, the problem came back... or maybe I did not notice it at first... or it appears from time to time... well, I don't know what to do.

After riding my 36" Nightrider tire today, both of the above comments make sense to me. I ride my tire with about 60psi and under normal conditions it is hardly effected by road camber, until today. I previously posted a video showing the effect of tire pressure and there is a big difference in camber effect. However today I went out with my tire at 60psi but the temperature was right at freezing. The road was dry and I rode the very same road that I ride in warmer temperatures. The camber effect was much worse with the colder temperature and I suspect that the tire rubber is harder and is less flexible the colder it gets. I was so surprised at the negative camber effect that I suspected that I had set the tire pressure wrong before the ride. I double checked the pressure when I got home and it was right at 60 psi.

So I could see how the harder and softer rubber in the same tire could cause the tire to turn one way if there is more hard rubber on one side then the other. Also as Fuxo reported the very same tire can preform differently. I have seen that tire pressure and now temperature can have a great effect on how a tire handles camber and maybe even in this special case of the tire turning to one direction.

Jim

[JohnIb]

Have you tried riding the tire off road? Maybe it doesn't like hard surfaces?