I've been pondering the Tubolito thread (started last autumn http://bearbonesbikepacking.co.uk/phpBB ... =7&t=10974)and my "How many spare tubes do you carry?" thread started a couple of weeks ago and it dawned on me to ask whether anyone has considered carrying a 700C tube to use as a spare in a 29er tyre to save weight and bulk? I've successfully used Specialized DH tubes in fat bike wheels with no problems (even though they're significantly narrower than a fat bike tube) and was thinking the same logic might work for a 29er set up. I figure that two 700x45 tubes wouldn't be much heavier/bulkier than one 29x2.2. Even carrying one 29er tube and a 700C as a just in case might be worth a try maybe? What's the consensus? Am I nuts?

Schwalbe SV19a

If it's a small 29er tyre, I'd go for one of these: https://www.sjscycles.co.uk/inner-tubes ... -to-44622/

If you're feeling more risk averse, then this: https://www.sjscycles.co.uk/inner-tubes ... 622-40635/

I've seen a 26" tube used in a 29er successfully before. Not by intention but because when I still rode 26" and my mates had 29ers I had the only tube with us so it was that or push it home. Worked ok and finished the ride albeit was less than 10 miles to go. Obviously the more a tube is blown up to fit the bigger tyre the thinner it is but it's only a short term fix so should work ok as a back-up.

A small tube in a bigger tyre will work (like the OP I use the Specialized DH tubes in my fatbike) but it's almost impossible to patch properly as the amount of stretch gets too much. Traditional patches tend to be more successful than the instant kind. If you're fitting it , then riding home, not much of a concern. If there's a chance of further punctures then just be aware.

chris n wrote:If it's a small 29er tyre, I'd go for one of these: https://www.sjscycles.co.uk/inner-tubes ... -to-44622/

If you're feeling more risk averse, then this: https://www.sjscycles.co.uk/inner-tubes ... 622-40635/

Thanks, I've been struggling to find these online.

I've always carried one of those lightweight Schwalbe road inner tubes as my spare and carrying two would still be lighter than
one of those great big 29er tubes!