Spiral scrape on rear tyre.

[newcross]

Oh, dear. Timbo's bike also got the spiral...

In my case, as I mentioned earlier, the chain was stretched, but wasn't loose enough to accept the tighter tentioner setting. Maybe it only comes to contact with the rim of gearbox while riding...

I got some replacement parts from Mayhem and open up the gear box to replace them by myself just before the first london meet. Interestingly, the chain (was secondhand) is just the same length as the previous one. After a week of rather intensive riding, I noticed a sign of the scrape's coming.
However, two weeks since then, there isn't any progress of scrape so far.

I think there are many aspects contributing to cause this problem as dcool and gold682 suspects.

Rider's weight, looseness of the chain, air pressure, road condition and flex of gear box (2-3mm flex that is) etc.


Mis-aligned gear wasn't evident in my case, but maybe more close inspection will help(?)

BTW, I'm rough on my A-bike, but not as rough as putting my full weight on a pedal, and I'm about 65kg.

[Timbo in Essex]

Dear all,

I promised in my last message i would let you know how I got on with my wheel scrape problem.

I e-mailed "support@mayhem" but received no answer what so ever - they really do need to sort out their e-mails - so I phoned and got immediate service. I took my bike back to Mayhem at North Acton and they willingly replaced both the chain and the back tyre. There was a bit of a misunderstanding about what work needed to be done and an incorrect re-fitting, by Mayhem, of the inner tube but this was sorted out with good humour and in the spirit of true customer service. I was very impressed with the service I got from Keith and Matt at Mayhem and I now have my A-Bike back on the road.

I would recommend that should anyone have a similar problem they contact Mayhem BY PHONE and get their bike repaired before futher damage is done.

Regards to you all

All the best

[Leo]

hi people

after a couple of kilometres of riding, I experienced the same notches in my back wheel.

when pulling down the chain, it became evident that it had stretched (worn out) and as soon as i would drive over a bump, would be loose enough to jump down and get caught between the tire and the plastic (causing marks).

so i adjusted the tension to "H" and, as expected, the wheel would not run too smooth anymore, basically stop at a certain position.
I figured it would be due to the higher chain tension, and a faulty back axle that now, unlike before when the chain was loose, stopped the wheel.

however, after loosening the screws again, the wheel turned easier (without braking every half turn).
I decided putting the screws in without the little metal rings (washers, shims??) that go between the screw head and bearing.

well I never had a smoother-turning wheel before. seems that the rings grind against the casing of the bearing when installed. (bad design)

Nevertheless i put them back on, as without them the plastic mounting is allowed to move too much and i dunno if that stresses the parts and causes early wear.

Conclusion:

well thats hard. if your back wheel is not turning lightly, try removing them and see what happens. Or maybe install new ones (I have none that fit jet). If you have the time, just post if you experience the same problem, as I am interested if its just my bike.

enjoy riding!

Leo

[rongood]

I recommend shaving off the lip formed on the crankcase housing that narrows the gap between the tyre and the housing. This narrow gap causes even a very slightly stretched chain to get caught and cause damage to the tyre, or break the chain, or even tear up the bearings. If you shave off that lip, the chain can safely drop as it stretches, causing no damage. It is not unusual for bicycle chains to stretch and it is normal to allow tolerance for such stretching. I shaved mine off using a Dremel rotary tool with a grinding bit, but you could just file it off. Be sure to take the housing off the bike before doing the work to avoid getting shavings up in the gears.