Cannot Fit Extralite Stem on Carbon Steering Tube

[Splash]

i tried to fit this brand new stem on my brand new carbon steering tube.

both are supposed to be made for each other - size wise.

i have this stem:

http://www.extralite.com/Products/roadstem%20OC.htm

i have the binachi oltre xr steering tube at 1 1/8".

The stem clamp is around 0.5mm too small.

i have emailed extralite (original place of purchase) for next steps.

can i ask you guys what my next steps should be?

can i somehow increase the inner diameter of this stem without affecting it's integrity?

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[ultraman6970]

Take the bolts out (or use one from another stem that fits) and put them at the other side, the reason is because I imagine the threads are at the other side only... and put a coin in the middle. Crank the bolt against the coin and that will open the "clamp" system they designed.

Repeat the action in the second bolt or do both at the same time, and see how it goes.

Hope this helps.

[93legendti]

I had this issue once. I couldn't get headset spacers to slide down the steerer tube. It turned out the expander bolt inside the fork's steerer tube needed to be backed off a bit and then headset spacers could be installed.

[Splash]

thanks ultraman - just tried that and i cannot fit the bolt in the other side where the thread is because the hole is too small.

93legendti - where exactly can i find this expander bolt? do i need to remove the fork?


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[Peter B]

The expander bung is inserted into the steerer tube and 'expanded' by tightening an allen screw after the stem & any spacers are placed over the steerer. Next the top cap is installed and another allen screw tightened lightly to preload the headset bearings by pulling up against the expanded bung. Finally, the stem bolts are sequentially tightened and torqued. If the allen screw that expands the bung was not loosened after removing the top cap & stem then the expander may exert enough outward pressure on the steerer tube to enlarge it just enough to make sliding a new stem in place very difficult. Look down into the top of the steerer and you will see an allen head screw ~6mm. Try loosening it slightly, then sliding the new stem on.

I'm sure you can find some relevant images on Google or via the Park Tool website.

[Splash]

thanks peter.

upon looking down into the steer tube with a torch, i do not see any allen key screw - just hollow carbon fiber tube.

no previous expander bung or previous stem has been placed in/on this steer tube.

is 0.5mm interference enough not to allow this stem to slide on?


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[Splash]

DONE!

i lightly sandpapered the inside of both stem c-clamps to ensure smoother transition onto tube.

thanks for your help guys..

As this new steer tube is uncut, i have 55mm of carbon tube remaining above the stem and a 5mm spacer below the stem.

This 55mm of excess tube will not be cut down for a while until i confirm optimal headset\stem setting configuration.

Is 58mm of spacers above the stem too much for a carbon steer tube?

Irrespective of rider position, what is considered the maximum amount of spacers one can use above and below a stem for carbon steer tubes to limit steer tube stress?

anyone know these 2 values for the bianchi oltre xr??

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re: this discussion on expander bolts/bungs, etc. i am still unclear.

i have this for my headset :
Fsa Orbit C-40-CF-ACB + Carbon Ti X- Plug with logo Bianchi
http://www.fullspeedahead.com/products/326/025000_Orbit-CF-40

i do not have any other expanding bolts except for the single screw integrated into the top cap. this screw is about 33mm long and has expander bungs encased around it so as you rotate this screw, the bungs expand inside the steer tube.

i do not see any other bolts inside the steer tube.

what else should exist ?

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[Splash]

Look down into the top of the steerer and you will see an allen head screw ~6mm.

is this allen head screw exist in carbon steer tubes or just alumuium?

i could not see this allen head screw.

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[Peter B]

Most expanders use some version of a wedge to hold fast inside the steerer tube and resist the upward pull of the top cap during subsequent preloading. Commonly they use an upper and lower conical cup in either end of a knurled aluminum sleeve cut along its length. The upper and lower conical portions thread together in some fashion and as the threaded component is tightened they squeeze the center knurled sleeve outward, exerting enough force against the steerer to hold the assembly in place while the spacers/stem/top cap are installed and preloaded. There will be a female allen hex cut in the top portion of one of the conical caps. Often it is difficult to see. The bolt that holds the top cap will usually thread down thru the center of the upper conical tap. In some designs the top cap threads onto male threads formed as part of the upper section of the expander. Once the stem bolts are tightened the expander isn't doing any real work other than affording some internal reinforcement in the area of stem clamping force (this should not be underestimated IMHO).

See what I mean here.

http://tinyurl.com/lvnjwx2

[ultraman6970]

If the fork is new and looks like he doesnt see a single thing in there would not surprise me that the fork doesnt have a expander installed (picture posted before).

Stupid comment but w/o the expander the OP wont be able to tight the headset and fork.

Interesting headset, the lower bearing is just squared.

[Splash]

comment made by lhuerta on the other thread...

"The compression plug on FSA installs the same as ENVE you just posted,and your top cap threads on to the bung or compression plug, then you use the top cap for applying proper compression/pre-load on your headset bearings."

i am deducing from this that the headset and fork can be tightened with the single compression plug on my fsa unit. Let me know if this deduction is incorrect.

Great detail PeterB!


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[PJN]

You shouldn't be working on your own bike if you're this clueless.

Find a shop that will take the time to teach you about these things. Not the Internet.

You're going to end up breaking something or hurting yourself if you don't know where to start on swapping a stem and tensioning a headset.

[Splash]

Thanks PJN.

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