Front inner tube inside the rear tire?
 

Is it possible to use the front inner tube (21 inches) inside the rear tire (17 or 18 inches)? Of course, I only mean it as a back-up solution, like riding 200 kilometers to the next town at very low speed. Have you tried it? It would reduce a lot of bulk and weight for the spares.

Pierre Saslawsky
http://www.photobiker.com

Yes, works ok. http://www.horizonsunlimited.com/ubb/smile.gif The reverse doesn't http://www.horizonsunlimited.com/ubb/frown.gif

Sadly, the rear is where you get the most flats.

I carry both, but make sure they are the inexpensive ones - they pack much smaller than the high quality tubes. I put the good tubes in with new tires.

Note that the good tubes are more "rubbery" and when punctured don't tend to tear like the cheap vinyl tubes do, which of course makes for a much more exciting flat.

I don't bother with the super heavy duty off-road tubes - more trouble than they're worth for us.

Grant

I've never tried using a 21" tube in an 18" or 17" tyre, but I only carry a (small when packed) 21" tube as a spare, and AFAIK other off-roaders I know do likewise.

Of course I also carry a puncture repair outfit as in my experience punctures come in groups....

A real benefit of a tube that hasn't torn is that it can be patched and reused...until you run out of patches... http://www.horizonsunlimited.com/ubb/smile.gif

In my experience, punctured tires are quite likely to get torn in the process (especially around the valve) and patches don't always work (the glue is bad, or the hole is too big, etc). It's much better to fit a spare inner tube and have the punctured one fixed at the next "llanteria" that has a hot press - but still keep a patch repair kit, just in case...

Grant are you saying you don't believe heavy duty tubes reduce the chances of a flat? Curious as it's rare for someone to give thumbs down on HD tubes.

I'm a believer. Two guys and I on KLRs with 4 mm tubes front and rear rode 75000 miles total thru Mexico Central and South America with not a single flat.

They're marginally more challenging to change, weigh more and take up more space, but if they reduce chances of a flat, it's worth it. The question is, do they~~

I don't think heavy-duty tubes reduce the chances of a flat if you hit a nail or a thorn but they will probably reduce the chances of having the tube completely wasted in the process. Also, it seems to me that they can take some serious repairs. Once or twice I had a patch made at the hot press that was so large and deep, I don't think it would have held on a normal tube. Another reason to mount them is to ride on sand with a lower tire pressure.

In the end, I'll continue to use the heavy-duty kind but as a spare, I'll just take one regular front tube.

For serious off-road, yes, they're good - but most HU people are long distance travellers - and normally run higher pressures and more street-oriented as opposed to full knobby tires. They also run hotter at highway speeds, which increases tire wear and pressure rise.

Finally, yes they are a bit tougher to fit.

Are they a good idea? Up to you - for mostly highway long distance use, I think not - for off-road, sure.