Marcus Helman wrote:
> I have a generic hollow axle that I need to cut down to use
> in a frame with 120mm spacing. How long should the axle be?
> The frame has Campagnolo long horizontal dropouts.
122-130 mm.
One mm sticking out each end is usually enough to locate the axle in the slot. The faces of the axle and QR hold your weight when the QR is tight, so strength is not an issue. I have used an axle of less than 120 (no stick-out), which works fine except for being harder to put the wheel straight in the frame, with the brake pads hitting the rim right.
On the long side: If you took the conical springs off the skewer you could let the axle stick out past the outer face of the dropouts by a millimeter or so, but this is dangerous and never necessary, so keep the axle shorter than the outside faces. Some dropouts are as thin as 5 mm, which is why I gave 130 as the max for the axle.
The symptom of too long, with horizontal dropouts, is the axle slips forward on the right side under hard pedaling. Note that if the axle is a little too long, it will be only the adjusting cone side that slips - the cam side will grip regardless. So if you had to ride the bike like this to get home (and taking the conical springs out wasn't enough), flip the skewer around to put the cam on the right side of the bike - forces tending to make the axle slip are much lower in magnitude on the left.
Your over-locknut dimension on the hub might really be 121, sometimes more, in which case you can adjust those numbers up accordingly. Shoot for the middle of the range and you can't go wrong.
Mark Bulgier
Seattle WA USA