Schwalbe Tyre Problem

[S.Giles]

Hi,

I have just upgraded the tyres on my six week old Engwe L20 Boost to Schwalbe Super Moto-X's (20''x4'') but have noticed a problem.

When I ride on a smooth road surface I feel a regular 'bump' through the saddle, seemingly emanating from the rear tyre and corresponding with each rotation of the wheel. It is most noticeable at low speeds.

I took the tyre off the wheel, inspected it and carefully re-seated it on the rim, but the problem persists.

Does anyone have any thoughts about this? I have contacted Schwalbe but have not yet received a reply. I re-used the stock inner-tubes when I changed the tyres BTW. There is no damage to the wheel rim, and the wheel spins freely.

Thank you.

Steve

 

[6zfshdb]

Have you checked to see if the tire is balanced? Is the rim bent or out of true?
This can be an issue, especially if you use sealant in your tubes.

Welcome to the forum and please keep us posted on the problem.

 

[Jeremy McCreary]

Welcome aboard! Interested to hear what your mystery bump turns out to be.

What do you see when you spin the wheel slowly and sight along tangents to the tread and sidewalls? Anything look out of round?

 

[jabberwocky]

It can happen when the bead doesn't fully seat somewhere, so the tire is out of round. It can also happen when theres a failure or defect in the tire casing causing it to bulge at one location. Could also be a hop in the wheel itself (a spot where uneven spoke tension is causing the wheel itself to not be round and bulge out).

Spin the wheel with it off the ground and see if you can spot anything obviously out of round. If there is, you have to play detective and figure out the cause. If the wheel is out of round but the rim looks true, its the tire. Look at the bead (where the tire meets the rim) in that area and see if it looks different; if it does pull the tire completely off and reseat it. If the rim looks good and the tire bead looks good but the tire has an out of round spot, defective tire.

 

[S.Giles]

Thank you for the welcomes and comments.

Spinning the rear tyre doesn't show anything unexpected. The tyres have a white reflective line around the side wall, and this would accentuate any discrepancy.

The bike is almost new, so there is no damage to the rim.

When riding, it feels as if the tyre has a small area where the rubber is thicker, which contacts the road once every revolution and causes a bump, but I'm really just guessing here.

I suppose I could swap the front and rear tyres and see what happens, but I'm not looking forward to having to do that.

Steve

 

[S.Giles]

It can happen when the bead doesn't fully seat somewhere, so the tire is out of round. It can also happen when theres a failure or defect in the tire casing causing it to bulge at one location. Could also be a hop in the wheel itself (a spot where uneven spoke tension is causing the wheel itself to not be round and bulge out).

Spin the wheel with it off the ground and see if you can spot anything obviously out of round. If there is, you have to play detective and figure out the cause. If the wheel is out of round but the rim looks true, its the tire. Look at the bead (where the tire meets the rim) in that area and see if it looks different; if it does pull the tire completely off and reseat it. If the rim looks good and the tire bead looks good but the tire has an out of round spot, defective tire.

I've checked the seating of the beads in the rim, and the wheel is cast aluminium, so doesn't have spokes. There's nothing obviously out of round.

I'm no expert, but it's looking to me like a manufacturing problem.

 

[Base]

Tube between tire and rim? After checking that you could run the lowest permitted pressure in de tube and see what happens. Also check the carcass threading of the tire, if there has been a mis match in that the tire looks ok but it could burst, most visble when you pump the tire to the max pressure permitted. Also spin the wheel and place your hand around the tire (like gripping it) so you could feel any lumps and bumps in the tire.

 

[S.Giles]

Today I noticed that if I raise the rear wheel off the ground and activate walk mode so the wheel spins slowly, the tyre is not consistent all away around its circumference. I wouldn't go so far as to call it a 'bulge', but there's definitely a part of the tyre that is not completely smooth. It's easy to see this when the wheel is revolving, but almost impossible to see when the tyre is static. It looks the same as it feels, if that makes sense.

Spinning the front tyre doesn't show any such thing. Seems I bought a turkey.

I guess I'm just waiting for Schwalbe to get back to me now.

Many thanks for your comments and help.

Steve

 

[S.Giles]

It's actually pretty obvious when the wheel is spun in walk mode.