Carbon rims, rim brakes, big mountains and heat - rim tape?

Tech
1

hello collective,

following question/problem/thoughts:

I have a rim brake equipped bike with carbon rims (Campagnolo so NO rim tape needed by design). When descending big mountains - we are talking really big e,g. Col de Nivolet or Colle dei Morti with really steep parts and many hairpins, so a lot of braking is needed in quick succession - the rims, of course, get quite hot especially in Italian summer. And there is the fear of a tube blow-out or airloss. I have TPU tubes, so it is rather the latter (happened last year during the great Gran Fondo Fausto Coppi when on the descent the speed was limited to 20km/h due to road works).

Now I have heard that a rim tape, cotton (e.g. Velox) or maybe Kapton tape, might help to limit heat transfer from rim to tube.

What are your thoughts on this? Or better than thoughts, knowledge!? Yes, No, maybe…?

And: no, disc brakes are not an option. Same goes for tubeless. And yes, I know how to brake on mountain descents with carbon rims. :slight_smile:

2

Cotton rim tape will limit heat transfer a bit. Whether it’s meaningful enough to reduce a chance of blow outs, no idea…

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3

I wonder if adding rim tape, particularly a thicker type, will result in insufficient G Height??

4

Previously i’ve had normal plastic rim tape installed due other security concerns connected with the tires i am using by the frame builder and getting tires off and on the rims was a big big pain. But maybe cotton tape is thinner?

5

Anecdotal only: I have one friend who overheated his rims and blew off the tires on a fast road descent in NorCal. He was running cotton rim tape (Velox, IIRC). YMMV, but it was a contributing factor in my transition to several of your verboten items: tubeless and disc brake.

6

sounds bad. hope ur friend is fine. yes, I have put one or 2 thoughts into buying a new bike with disc brakes. but I like my current bike too much and dislike the idea of a much too complicated system (e.g. threaded #44 by dave rome on our favourite cycling-website just today or yesterday). and this would be just for one, 2 or 3 visits to the mountains in a year (where I live the nearest mountains are over 200km away and the longest descent here is maybe 1km long and 60m down), so I decided not to do it and rather save the money for some trips to some mountains where I will be braking more carefully and maybe even taking a break in the descending and breaking :slight_smile:

7

I though, but maybe I’m wrong, that tpu tubes are less recommended than buty tubes.

Maybe you can also go for fatter/commuter tubes, weather TPU or butyl.

8

To state what is likely obvious: I think the cheapest solution to be safer would be a decent set of aluminum wheels. Maybe you can find a set used, given all the folks who are abandoning rim brakes? I too know of people who have had carbon rims fail on mountain descents. I’ve ridden various mountains on a rim brake bike, and I would just never do it with carbon rims. (If it’s wet, which of course can happen unexpectedly, those are also terrible for stopping.)

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