Back wheel wobble

Mussels

Esteemed Pedelecer
Jun 17, 2008
3,208
8
Crowborough
I have on occasions a strange sensation coming from the back of my bike, it feels a little like the back wheel has turned to jelly for a moment. I first thought it felt like the wheel had come out of the dropouts and was wobbling, I knew this hadn't happened but it was enough to make me check the axle was done up tight. Another description that came to mind was that it felt like the wheel had buckled slightly for a moment.
This is not happening over the biggest bumps and down bumpy dirt tracks it feels exactly as I expect it to, this is where I would expect a problem to show up most. Instead it is happening on the road over little bumps and I'm guessing it is the back wheel slipping and regaining it's grip. I have done a lot of motorbike miles so I'm used to tyre losing grip momentarily but these aren't motorbike tyres and the sensation is different. Is this normal or is it a sign of problems to come?
I have a hub motor in the rear wheel which has been built by SJS using a Rhyno rim, so I would expect any flexibility in the wheel to be by design. The non-drive side spokes are fairly loose but not rattling so I think it is all normal and as intended, generally the wheel feels fine and over bumps is better than the original wheel. I have a Travel Contact tyre which is mainly slick and I wonder if this is slipping about.
Any thought as it is a bit unsettling, if it is normal tyre behaviour then there is no way I'd want to fit one of these to the front wheel.
 

flecc

Member
Oct 25, 2006
43,913
19,990
This does sound like tyre instability in some conditions. You could try experimenting with some different tyre pressures, one much higher, one lower, to see how that affects it. It may point to whether the tyre is playing a part in this.
.
 

Mussels

Esteemed Pedelecer
Jun 17, 2008
3,208
8
Crowborough
This happend to me when my tyre split.
Was it before or after your tyre split? When my last tyre split there was a very loud bang followed by a 3 mile walk home.
This does sound like tyre instability in some conditions. You could try experimenting with some different tyre pressures, one much higher, one lower, to see how that affects it. It may point to whether the tyre is playing a part in this.
.
I'll give that a go if it happens regularly enough to monitor, I didn't notice it at all this morning but sometimes I'll feel it a few times in a journey. I didn't mention it before but the tyre is incredibly tight on the rim, so much that the ABS tyre levers don't have a hope of getting it off. Could this cause instability?
I think it may be time for me to order that Big Apple I've been toying with fitting, just so it's ready in case the Continental one fails. :)
 

flecc

Member
Oct 25, 2006
43,913
19,990
I've never known tightness on the rim causing this problem. It's usually a tread pattern or tyre wall characteristic on some bikes. For example, I've used 26" and 700c Marathon Plus tyres for years and they've been very stable, but on the 20" rear wheel of my Q bike this tyre pattern displays exactly the apparent slide out form of instability you describe. Also just as with you, it's not consistent, varying with bike load, road surface etc. I've just learned to live with it and automatically compensate, since it's never lost all grip.
.
 

bogmonster

Pedelecer
Aug 8, 2008
127
1
I have on occasions a strange sensation coming from the back of my bike, it feels a little like the back wheel has turned to jelly for a moment. I first thought it felt like the wheel had come out of the dropouts and was wobbling, I knew this hadn't happened but it was enough to make me check the axle was done up tight. Another description that came to mind was that it felt like the wheel had buckled slightly for a moment.
This is not happening over the biggest bumps and down bumpy dirt tracks it feels exactly as I expect it to, this is where I would expect a problem to show up most. Instead it is happening on the road over little bumps and I'm guessing it is the back wheel slipping and regaining it's grip. I have done a lot of motorbike miles so I'm used to tyre losing grip momentarily but these aren't motorbike tyres and the sensation is different. Is this normal or is it a sign of problems to come?
I have a hub motor in the rear wheel which has been built by SJS using a Rhyno rim, so I would expect any flexibility in the wheel to be by design. The non-drive side spokes are fairly loose but not rattling so I think it is all normal and as intended, generally the wheel feels fine and over bumps is better than the original wheel. I have a Travel Contact tyre which is mainly slick and I wonder if this is slipping about.
Any thought as it is a bit unsettling, if it is normal tyre behaviour then there is no way I'd want to fit one of these to the front wheel.

Maybe a silly question but is your inner tube the correct size. I bought a mountain bike secondhand and had trouble with tyres. I swapped them with road tyres in the end but I beleive the issue was that the tyres were 1.95inches wide whereas the tubes were only good for upto 1.75 inches wide.

It caused the tyres not to sit cponcentrically on the rims and for the tyre walls to collapse and twist. I think this would be particularly bad on a thin sidewall type...
 

Mussels

Esteemed Pedelecer
Jun 17, 2008
3,208
8
Crowborough
Inner tube is the right size, I checked when I fixed a puncture last night. The puncture is due to a cut that goes through the rubber and the fabric, that's quite possibly what is causing the bad handling. The pressure went down again today so if I can find the receipt it's going back to the shop under the Continental guarantee.
I've ordered the Big Apple replacement, I just hope it turns up before the old one falls apart and that it fits under the mudguard.
 

halflife

Pedelecer
Jul 12, 2008
33
0
My bike had a wobble in the back wheel but on closer examination it was only in the tyre. Changed the tyre and the problem went away. I think I may have previously put the wrong size tube in though:eek: and distorted the tyre in some way.