Stem and Cap Bolt

[Hacienda71]

Quick question I have replaced my headset recently and the top cap and bolt seem to be inside the stem. I have followed the correct order of tightening the stem and cap bolts there is no play in the headset, but it looks odd. Is this usual or can you get a wider top cap?
Cheers

 

[Globalti]

Yes, you need a bigger cap.

 

[02GF74]

weird - you using oversize stem with shim perhaps?

deffo need a bigger cap.

you do up the cap so it pulls all the gubbins to remove play from the bearings then you tighten up the stem to hold it all in place, I could be wrong but is how I've been doing it for years without probs. (seems logical way)

 

[Hacienda71]

Cheers Guys that is what I thought. It is such a tight fit that is compressing the bearings but just looked wrong. Trip to LBS tomorrow me thinks. The problem maybe it is 1" forks so it is as 02 guessed with a shim.

 

[Aperitif]

Wow - lucky the forks aren't rattling around!

Threadless headsets work on the same principal as threaded headsets. The bearing races need to press against the bearings. The bolt in the top cap will put pressure on the stem, which presses on washers below the stem, which press on the bearing races, which press against the bearings.

NOTE: The cap and bolt at the top of the stem do not secure the stem onto the steering column. The bolt or bolts on the side of the stem keep the stem from moving once the adjustment is made. The cap is used for bearing adjustment only.

All that from here:
http://www.parktool.com/repair/readhowto.asp?id=65

 

[rustychisel]

yep, that's a 1 1/8 stem with a shim, and the topcap you have is for a 1in steerer.

 

[MartinC]

This is the problem with 1" steerers. Almost all stems are now 1 1/8" and you have to use a shim. If you've got spacers above the stem you'll need a 1" top cap if you haven't then you'll need a 1 1/8" top cap.

1" spacers are an interference fit with the stem (i.e. they're wider than the hole in it) but a 1" top cap is usually narrower (outside diameter) than the 1" spacers. A 1 1/8" top cap is usually wider than 1" spacers.

So without spacers on top of the stem you'll need 1 1/8" top cap so that it bears on the stem not just the shim. A 1" spacer on top of the stem will bear on the stem fine but a 1 1/8" top cap on top of this will stick out and offend the aesthetic sensibilities of the more sensitive amongst us.