Shimming 1" Steerer for 1 1/8 Stem

[carlucci1106]

Doing a threadless conversion on my CSI and I'm planning to use a Thomson shim for the stem. It's hard to picture how it works with spacers. Does the shim become like a spacer in that your 1" spacers butt against it, or do you use 1 1/8 spacers?

[Louis]

You use 1" spacers and the shim sits on top of that. 1 1/8" spacers would not stay centered. However, I've never done it, so I'm not sure what happens to the stem. I think the 1" spacers have an OD that's big enough to prevent the stem for just dropping down all the way to the headset.

[nighthawk]

I went through this on my last build. You can really do either. If you use 1 1/8" spacers, you'll need to shim them as well. There's all kinds of shims out there with different stack heights. I ended up going with 1" spacers (about 2cm below stem) and no spacers on top (with a 1" top cap). It ended up being mostly an aesthetic decision (using 1" spacers) based on the headset (CK) and the stem (enve) I was using. The 1 1/8" spacers I think had a larger OD than the bearing cap of my headset, so it looked all wrong.

[carlucci1106]

I went through this on my last build. You can really do either. If you use 1 1/8" spacers, you'll need to shim them as well. There's all kinds of shims out there with different stack heights. I ended up going with 1" spacers (about 2cm below stem) and no spacers on top (with a 1" top cap). It ended up being mostly an aesthetic decision (using 1" spacers) based on the headset (CK) and the stem (enve) I was using. The 1 1/8" spacers I think had a larger OD than the bearing cap of my headset, so it looked all wrong.

I am using the CK headset as well, so if it looks better with the 1" spacers, I'll do that. Thanks

[ultraman6970]

1st thing, the length of the shim, larger the better because if too short it might not get enough surface to grab and it wont work as intended.

Second reason to use a larger one is because you can center the 1 1/8 spacers in the shim so they will center easier than w/o the shim obviously. you have to use 1 1/8 spacers or will look quite alien to have 1 inch spacers then the shim with 1 1/8 spacers and stuff.

No idea of your set up (# of spacers upper or bellow the stem) but is pretty much straight forward, put the shim put the stem put spacers (if you use spacers above the stem) and tight headset/fork/stem as usually.

Good luck.

Doing a threadless conversion on my CSI and I'm planning to use a Thomson shim for the stem. It's hard to picture how it works with spacers. Does the shim become like a spacer in that your 1" spacers butt against it, or do you use 1 1/8 spacers?

[nighthawk]

Ill try to take some photos of my setup for reference. Do you plan on running any spacers on top of the stem? I did not and so it was important to make sure the shim was a few mm shorter than the stack height of the stem. This allowed the top cap to properly depress the stem.

Thomson makes two different sizes (stack heights)... There's also some from Problem Solvers, and Velo Orange, etc.

[carlucci1106]

Ill try to take some photos of my setup for reference. Do you plan on running any spacers on top of the stem? I did not and so it was important to make sure the shim was a few mm shorter than the stack height of the stem. This allowed the top cap to properly depress the stem.

Thomson makes two different sizes (stack heights)... There's also some from Problem Solvers, and Velo Orange, etc.

I shouldn't need any above the stem as I calculate. 173mm Steerer with 950mm headtube. CK cites 28mm Stack height of HS. Stem is Stella Azzura Espresso (about 40mm?). Should leave only 1cm, which can go on the bottom. So should I go with the 37mm Shim and then that way there would be a slight deficit between the stem and steerer for the top cap?

[ultraman6970]

In my experience ok??? the issue is that you wont have enough surface at the top... the stem will be hold by 1 clamp instead of two. But you have to test because at least with my stems when i needed a shim in a set up like yours the stem was not holding.

From what i understand of your description....The other thing is that if the steering tube is carbon you dont want to overtorque the top of the steering tube because the stem bolt might be at the edge of the steering tube right?

You have to test man, looks like your set up is quite tight and not much room. IMO with shims better excess than deficit.

[roydyates]

I went through this on my last build. You can really do either. If you use 1 1/8" spacers, you'll need to shim them as well. There's all kinds of shims out there with different stack heights. I ended up going with 1" spacers (about 2cm below stem) and no spacers on top (with a 1" top cap). It ended up being mostly an aesthetic decision (using 1" spacers) based on the headset (CK) and the stem (enve) I was using. The 1 1/8" spacers I think had a larger OD than the bearing cap of my headset, so it looked all wrong.
As nighthawk says, there are lots of ways. But my experience has been that the easiest and nicest solution is to have the shim height exactly match the stack height of the stem. In this case, the stem acts just like a one-inch stem and you can have one-inch spacers above or below the stem in whatever config is best.

[nighthawk]

As nighthawk says, there are lots of ways. But my experience has been that the easiest and nicest solution is to have the shim height exactly match the stack height of the stem. In this case, the stem acts just like a one-inch stem and you can have one-inch spacers above or below the stem in whatever config is best.

I agree, but for my situation I needed a slightly smaller shim (1-2mm) because of the shape of the underside of the top cap. I should have also mentioned this was on a full carbon fork/steerer and a Colombus compression plug.

[victoryfactory]

No need to get complicated.
once you slide the shim into the stem, it effectively becomes a one inch stem

You use one inch spacers.

Just make sure the shim is ever so slightly shorter that the stem
height so the whole package tightens down on the stem, not the shim.

Also it's good practice to rotate the shim's slot to be opposite the
stem's slot.

VF

[cogclog]

Maybe this is obvious but be sure that if the 1 1/8 stem is at the top of the steerer tube that you use a 1 1/8 top cap. I've seen many folks do this and use the 1" top cap that came with the headset which just compresses down onto the steerer tube instead of the stem.

[nighthawk]

Here's my set-up:

Carbon fork/steerer (columbus minimal)
Columbus expander plug with top cap
Chris King 1" Nothreadset
1" spacer (2cm)
Enve stem (40-41mm stack height)
Problem Solvers shim (38mm stack height)
https://lh5.googleusercontent.com/-w8micrtYzmw/UQ-0g2jyZeI/AAAAAAAABd0/IGV8ZAZtIGw/s400/Photo1.jpg

Here's a photo of what a 1 1/8" spacer would have looked like (with shim to take up gap space):
https://lh4.googleusercontent.com/-b9aQQYWYh8U/UQ-0hcU_rNI/AAAAAAAABeA/EaXfVtwYxVE/s400/Photo10.jpg

[nighthawk]

Exposed steerer with expander plug...

https://lh6.googleusercontent.com/-iPX16CEyAjY/UQ-0hq-IZHI/AAAAAAAABeI/lsRLfE0LTvg/s400/Photo12.jpg

1" spacer on top of bearing cap:

https://lh4.googleusercontent.com/-6JuXe1mn0H4/UQ-0kU4PqgI/AAAAAAAABfE/0wt0V7jfhbg/s400/Photo7.jpg

shim over steerer tube on top of spacer:

https://lh6.googleusercontent.com/-03MjcH5fA5c/UQ-0j_yvF7I/AAAAAAAABe0/z9WrskFOJRk/s400/Photo5.jpg

stem over shim:

https://lh4.googleusercontent.com/-CgajUAwTdXI/UQ-0jIPMwiI/AAAAAAAABew/VWvdwVtp-SM/s400/Photo4.jpg

Install top cap to torque. Torque stem bolts. Done.

[nighthawk]

The length of the steerer is important (as you probably already figured)...
I was able to cut mine specific to my needs. I don't know if you are planning/willing to cut yours, or if you are hoping to set it up with the length you already have.

Where it got tricky for me was the top cap.

Here's what the expander plug/shim/stem set-up looks like before installing top cap:

https://lh3.googleusercontent.com/-UKTfBf2GIBc/UQ-0iiOJkEI/AAAAAAAABes/cH-WM48W2PY/s400/Photo3.jpg

Here's a bunch of different top caps (enve, chris king, columbus, thomson - not necessarily in that order):
https://lh6.googleusercontent.com/-Ad91S5-4SmY/UQ-0ipEQOMI/AAAAAAAABeg/JLwraabgtL8/s400/Photo2.jpg

I wanted to use the enve to match the stem... I think 2nd from the left in the picture.. but the shape of it wouldn't work with the columbus expander plug. I ended up using the one that came with the expander plug and was able to get a much tighter compression on the stem.

Anyways. Good luck to you! It took me a lot of figuring to wrap my head around this before I did it.. cutting the steerer.. spacers.. shim.. stem.
In the end, the easiest, most common sense thing worked the best.

[druptight]

Thanks for the detailed pics. I'm going to have to go through this when I finish making my current frame, so I'll have to reference back to this thread.

[DRZRM]

I had a similar issue when I put a 1" F-3 threadless fork on my Legend, replacing a threaded F-1 and went to a 1 1/8" Moots stem. The difference is that I used a Reynolds compression plug which used a proprietary cap that requires some clearance over the steerer (like your situation), and required very specific heights (the top of the stem had to be 3mm over the top of the cut steerer tube). The steerer was cut already so I had to make the stem and spacers fit the length of the steerer. The clamp section on the Moots was pretty long, and fortunately was a bit longer (about 3mm) that the Thomson shim. As it turned out, slammed without spacers dropped the stem too low on the steerer, so I put a 1" spacer under both the shim and stem and no spacer on top (which is actually what Reynolds requires). That said, while researching my options, I found that there are different outer diameters on various shims, and you can pretty well match the outer diameters of a 1" and 1 1/8" if you dig around in your local bike shop's box of shims.



Obviously, as stated above, you have several choices based on length of stem and steerer. The most important thing is that you make sure whatever you jerry-rig, that your stem is clamping directly over the length of the compression plug in the steerer. Don't let spacers on top of the stem raise the compression plug out of the steerer.

Here's a link to my thread as well as one with a fairly big picture of the bike.

Link (http://forums.thepaceline.net/showthread.php?t=113585)

Image link (http://forums.thepaceline.net/showthread.php?t=115276)