Originally Posted by
Raleigh71
Thanks again for all the great info and ideas! I'm excited about the conversion.
Thumb shifters seem to be the way to go. It will take getting used to with friction shifters but seems to be the most ergonomic solution
I'll also convert the schrader holes in the rims to presta using the Wheels Manufacturing grommets (see photo). I was going to cut them down so they're flush with the outside rim when in place. Using threaded presta valve stems with the nut in position will provide for a stable seat for the valve stem.
I think these are the most logical solution from an an engineering standpoint of the several schrader to presta conversion options out there. But need to be cut down the the thickness of the rim so they're flush with the rim when in place, purely for cosmetic reasons.
Don't cut them down. They need to have a little height to stay in place if you lose pressure, the tube slips, and the valve tips over.
A friend had his Presta rims drilled for Schrader valves- his theory was that if he had to buy a spare tube at Wal-Mart (he rode a lot of self-supported tours), he could always use a Schraeder tube if that's all they had. I live dangerously- all my bikes have Presta valves and undrilled rims.