Rim heating and innertube failure

[pete]

The other day my girllfriend and I were making a descent down a steep hill on my xtracycle with some shopping. Part way down the front innertube failed ... luckily we weren't going too fast and managed to coast to a halt with only a twisted ankle. Wondering what had happened I checked the rim temperature and found it was very high - too hot to touch. I lugged the bike home and took the tire off to see what had happened. It turns out there was no puncture, but a patch from a previous puncture mend had failed, and the inner tube also seemed stressed in other places. My guess is that this was due to the increase in pressure as the rim temperature increased (since pressure is proportional to temperature at constant volume). This didn't surprise me as I've heard tandem riders have similar problems due to rim heating. Perhaps this would be worth mentioning as a safety issue in the XtraCycle handbook? - if the tube had failed at higher speed or at a busy junction the results could have been much more nasty.

Does anyone know of any solutions to this rim heating problem? I'm reluctant to get disk breaks as this would be very expensive, especially as I've an older FreeRad which seems to lack disk break mounts. I guess a combination of heat-proof rim tape and running tubes at a lower pressure would help.

Cheers,

Pete

[rock*]

Pete, glad you weren't hurt worse.

Certainly merits attention in the updated owner's manual. I haven't heard of any cure except for disc brakes. The only time I've heard of the issue coming up, there was always a passenger involved (i.e lots of extra weight). Anytime I'm carrying a passenger down a steep and/or long hill, I use the brakes sparingly (if possible of course) or make stops to check the rim temp and let the rims cool if necessary. Sometimes I even squirt them with water.

[quincywally]

It sounds like heat might not have been the cause.
Many tubes fail from riding with low pressue. The tube gets abraded by the inside of the tire casing. A cross-hatch pattern on the tube is proof positive of it. Xtracycles need higher pressure when loaded. Lower tires need even higher pressure. A 26 x 2.2" tire should be kept no lower than 50 psi.

[Abayye]

Aaron-- You wrote:

. Xtracycles need higher pressure when loaded. Lower tires need even higher pressure. A 26 x 2.2" tire should be kept no lower than 50 psi

.

Would you recommend even exceeding the tire manufacturer's recommended maximum pressure?

I've always been confused about this whole issue of tire inflation. Why would you ever want to inflate less than the max?

Thanks!

--Alan