latex tubes

yinya

two questions:

a) would there be any issues related to running a 700 x 22-23 rated michelin air comp latex inner tube in a 700 x 25 (michelin pro race 2) tyre?

b) what is the latex tube deflation rate i.e. are they even suitable for the longest audax rides?

I am asking because because there is a significant rolling resistance decrease shown in the many studies with latex over butyl tubes and naturally I'd like to save energy where I can...

chrisw12

Iirc the best test came when a 20 latex tube was put on a 23 pro race so yes you can use an undersized tube in a bigger tyre, but this may effect your second question. By stretching the latex more, do you make it more porous and so loose more pressure over time. Also by tinning out the tube you may be opening yourself up to more punctures perhaps.

If I was racing I'd not worry about it but for a long audax I don't think I'd risk it.

To answer the second question on its own. For a 12hr for example, yes a latex will loose pressure but I can't say I noticed any defference, tbh I was in so much pain towards the end that a few pounds of psi drop wasn't going to be noticed.

What I'll do with my tubs is pump them up a little higher than normal at the start (still below the manufacturers guide mind.) then by the middle end of the race they'll be at the more comortable pressures in theory.

pieinthesky

I ran a 2 inch knobbly mountain bike tyre with a 20mm latex tube (in an emergency) and it worked fine. I cant see it being a problem in a 25mm tube.

I have run them on Audaxes (not more than 200k) and didnt have a problem with pressure loss. However, in my experience they are less reliable and when they go they go suddenly and quickly. They were too much hassle and I wouldnt use them again.

maddog 2

I did the Fred Whitton with them. No problems.

They go a little soft overnight but over 8 hours they're fine. And a much nicer ride than butyl.