Presta? No Problem / R.I.P. Old Wheelset
My new Shimano-hubbed Sunrim Cr-18 wheelset arrived the other day, and to my chagrin - it's not drilled for Schrader valves, but presta valves (those tall, thin metal ones with threads). Nothing is wrong with presta valves - in fact they actually retain air better at high pressures - but the availability of tubes for wider tires is somewhat limited. So what does one do to remedy this problem, short of replacing the rims? Well, you drill the valve holes out, of course. Presta valves are 6mm wide, with a 6.4mm (1/4in) valve hole. In contrast, Schrader valves are 8mm wide, and have an 8.3mm (21/64in) valve hole. Luckily for me, the Cr-18 rims are wide enough to accommodate this wider hole; don't try drilling out thin rims, or those rims with a strongly arched profile, or you may end up weakening the rim significantly. Flat profile rims; its easily drillable. Select a few dill bit sizes for stepped drilling - this will prevent th...