D.J.M.

Could anyone please point me in the direction of instructions on how to properly mount a carbon fork?

Never really tried, but just wanting to make sure I make no big mistakes :-)

Thanks!

HillRider

The fork should come with an owner's instruction sheet and Park Tools has a tutorial on fork installation here: https://www.parktool.com/repair/readhowto.asp?id=111

Assuming the steerer is carbon DO NOT use a star nut unless your manufacturer specifically provides a special one. Use an expansion plug to allow adjusting the headset preload.

One more thing: you can always cut the steerer shorter. You cannot cut it longer. Measure a bunch of times before you get out the hacksaw.

chas0039

I have had difficulty getting the torque specs for the expansion plug, also is there any spec for how far down it should be mounted. Any suggestions?

HillRider

What make of expander plug?

125psi

Is your fork steerer tube carbon or aluminum?

operator

My bike is broken how do I fix it

fosmith

there's no hope...just give it to me. i'll "dispose" of it for you.

chas0039

The headset is FSA and the fork tube is carbon.

mcoomer

I just want to stress what was noted above. Once you cut it you can't make it longer! I purposely cut my steerer tubes longer than I think I need and use spacers until I've ridden the bike several times and am certain of the final positioning of the stem and bars.

HillRider

You asked abvout placing the expander plug so I need to know what make and type it is, not the headset. FSA makes expander plugs but there are others.

chas0039

Well, it came stock on my Ridley Aedon and I cannot be sure who made it as there are no markings. Must of the non-drive train parts are FSA so the best guess is the expander plug came with the headset and the cap on top (FSA). Sorry I can't give more info.

HillRider

OK, expander plugs come in two major design types;

1. The plug and top cap are all in one unit and held together with a long bolt and a spring to preload the expander. These use the adjusting bolt to expand the plug and adjust the headset at the same time. The adjusting bolt head will be flush with the top cap and look just like a regular star-nut adjusting bolt. You install the fork, add spacers and the stem, then stick the expander plug in and tighten the bolt to both grip the steerer and preload the headset. Look and Profile Design make this type. Here is a picture of Profile's:

https://www.profile-design.com/profil.../gap-cap-.html

2. Two piece types. The top cap has a 6 mm hex hole in it and has a cylindrical tube on it's underside that is internally threaded. The body has the actual expander and a externally threaded extension on top with a 5 mm hex recess. You remove the top cap and insert the body into the stem and tighten the 5 mm hex to expand the plug and grip the steerer interior walls. Then install the spacers and stem. Finally, thread the top cap down over the inserted body and tighten the top cap with a 6 mm Allen key to preload the headset. FSA makes this type and here is a picture of one:

https://www.biketoolsetc.com/index.cg...em_id=FS-CPSR8

The depth to insert this is sort of by eye. Insert the expander body far enough that the top cap won't bottom on it but the top cap can reach the threads enough for several turns. My FSA expander is set so the top of the body's projection is 8 to 10 mm below the top of the stem. Here is Salsa's .pdf on cutting a carbon steerer and installing this type of plug.

https://www.salsacycles.com/pdf/SalsaCarbonSteerer.pdf

chas0039

Thanks, and the torque spec for the expander bolt is......?

HillRider

I don't know about all of them but FSA gives the following torque specs for it's "Conix" expander plugs and headsets:

Tighten the body hex bolt to 175 in-pounds (14.6 ft-lbs or 10.6 N-m). Then tighten the top cap's hex to 105 in-lbs (8.7 ft-lbs or 6.4 N-m) to preload the headset.

One more thing while I think of it. After cutting the steerer and assembling all spacers and the stem, the top of the steerer muct be 2-3 mm below the top of the stem. This assures the top cap doesn't bottom on the steerer before the headset is properly adjusted.

For carbon steerers, I prefer to leave the steerer a bit long so it sticks up a few mm ABOVE the stem and use a 5 to 10 mm spacer on TOP of the stem to get the 2-3 mm gap. That way I'm sure the carbon steerer is completely surrounded and supported by the stem.

chas0039

Thanks, I figured the torque would be between 6-10 N-m given that it was carbon.