Fork spacers

[Chinbrook jedi]

I have just got a new frame and fork. The fork will now need cutting to size. It is an exact replacement for one I broke. The fork is carbon with alloy steerer tube.

On the old fork I had 30mm of spacers, but always thought I could do with going higher. I want to put another 10mm spacer on there. Would there be any problems with doing this?

As an aside how many spacers can you use?

Also I have a combination of 10 mm spacers and 5mm spacers, is it ok to use this combination or should I stick say a 20mm in. Does it matter?

[DaveM]

First question is is this a threaded steerer or threadless. On threadless, use whatever spacers you want because the stem holds the headset adjustment. On a threaded steerer, theoretically spacers are no issue, but I wouldn't recommend it. The lock nut on the top of the head set does two things. First it holds the adjusting cup from loosening (unthreading). Second, it stabilizes the cup so that all the bearing surfaces stay exactly parallel. Without the locknut, the cup would rock a little since it has some play on the threads and your weight won't be equally distributed among all the bearings. 1 or 2 thin spacers shouldn't hurt this. But as that stack gets taller, the stability of the whole thing drops and the headset will probably start flexing a little due to weight shifts, steering and braking forces, etc. I don't see that it would "snap-off" or anything, but might definitely shorten headset life.

I've seen people use 1" spacers to allow them to keep their stem higher (while still 'properly' inserted into the fork). They said they'd had no problems. Again, probably ok but not really recommended.

Overall, if you are a heavy or aggressive rider, don't do it. If you do do it, use the least number of separate spacers possible. At least one big one should flex less than a stack of thin ones.