Had a mare today, 3 punctures, a taxi ride to the nearest open bike shop (sadly only Halfords) and a train home later…
I asked for replacement tubes and was told this was what they had fitted and what would do the job ( I did query it at the time , but was tired and stressed).
My tyres are schwalbe marathon Mondial 700x40c which is obviously wider than the tubes purchased.
Will the spares work or, do I need to get new new spares from a proper bike shop when I can?
by Glad_Student_9354
12 Comments
In a pinch yes, full time maybe.
2mm will be fine, tubes and tyres are not an exact measurement and there are margins of error
Yes, it will be fine.
They’ll work fine. It’s better to use the larger size so the tube doesn’t have to stretch as much to fill the tire, so the smaller one will be SLIGHTLY more prone to punctures. Maybe. The quality of the tube itself matters much more.
If it were me I wouldn’t even bother swapping it until the next time I have to change it. It’s not “wrong”.
Yes
For sure.
Yes, no issues at all.
Absolutely. I’ve ran 700×23-28 tubes in a 29×2.2 in a pinch and had no issues.
Yes. Butyl is ridiculously stretchy.
I have a friend that races long distance and before TPU tubes she carried 26 x 1.5 tubes for her 29 x 2.4 tires to save weight
Pump up a butyl tube outside of a tyre and see how big it gets before you give up trying to see how big it gets before popping…
It will get to 1200 by 70, no problem.
2mm is nothing.
P.S. don’t try this with a tpu tube.
It’ll be fine. When you pop it and don’t feel like patching it just get a tube that is in the proper size range.
Absolutely no problems whatsoever.
Most (cheaper) inner tubes are made from butyl rubber. Butyl rubber is incredibly stretchy – it can stretch to between 300% & 800% of its original length (one day when you’re bored, pump up a tube outside of a tyre and see how big it goes before it pops).
It’s truly ridiculous for Halfords etc. to market these things with such precise measurements. The Bicycle Lord, [Sheldon Brown](https://sheldonbrown.com/adv-cycling/Brown_650B_Lives.pdf), used to even use 26” inner tubes with 650b (27.5”) tyres. If he can size up by 1.5”, you will be absolutely fine with a 2mm difference!