[Critter Cameraman]

Im instaliling my stem (nukeproof horizon) on my Rockshox REBA stearer tube and I know the stem top surface should be 3mm above top surface of stearer tube, buuut my spacers workout to a 1mm Gap or a 5mm gap. Is a 5mm gap acceptable? Thanks!

 

[wayold]

The safe approach that makes sure you have enough clamping force is to have the entire stem in contact with the steering tube and then put one or more headset spacers on top to give the top cap enough clearance to be tightened without interference (usually means the top of the spacer needs to be at least 2-3 mm above the top of the steering tube). When trying to max out stack height I have sometimes put the stem on top of all the spacers so that the top of the stem itself is 2-3 mm above the top of the steering tube, but making sure the entire upper stem bolt remains below the lip of the steering tube. Even then I think this compromises the stem clamping force somewhat and isn't a great idea. I certainly wouldn't mount the stem any higher.

 

[Fleas]

I would put the small spacer on top of the stem. 1mm is probably enough to compress the headset assembly, but you should check after you get it all together.

-F

 

[jeffrjohns]

Ideally you want the top of the stem (or spacer) to be 3mm above the steerer tube. I think 1mm is too small and your top cap will end up touching the steerer tube. I think 5mm is probably ok but personnaly would not take that chance, why not get a 2mm spacer and be safe.

 

[r-rocket]

1mm may be enough depending on your top cap. Only way to know for sure is to try it.

Leave the stem bolts loose so the stem turns easily on the steering tube. Torque the top cap to 3-4 nm

If it becomes harder to turn the stem on the steering tube, the top cap did not bottom out and you have enough space to adjust the headset correctly. All is good, adjust the headset like normal.

If the stem still turns easily, the top cap bottomed out on the steering tube before pre-setting the bearings. That's no good. Go with the 5mm gap for now, and get a 2mm spacer some day. You will be fine since you don't have a carbon steering tube.

 

[SteveF]

Chances are it will snug up and compress a bit when you put it together. Use the 5mm spacer.

 

[J.B. Weld]

Like this-

Spacer on top is best because both stem binder bolts get full purchase on the steer tube.