Weight Weenies

I ride a Tarmac with a stock Specialized stem. It seems the top cap is larger than standard, is that correct? Is it married to the stem, meaning if I change stem brands the top cap will be smaller/standard? Thanks for any input, I am ignorant on this! Btw, is the bolt size the same regardless?

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Anyone know about this?

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A picture is worth a 1000 words. But without one the Tarmacs all have 1 1/8" upper headset bearings which is as close to a std size as you can get. So the preload cap should be standard, and the bolt should be standard as well. Some stems have top caps that are mated to them, but without a picture it is hard to know what stem you might have.

Top cap that came with my frameset is standard. Replaced with

I believe the headset is standard, just seems I saw something about Specialized stems having oversized caps. Also, I recently bought a fun top cap which is too small, so thought I'd ask here for more specifics.

Here are a couple of pics... Thanks!

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mvcap wrote:I believe the headset is standard, just seems I saw something about Specialized stems having oversized caps. Also, I recently bought a fun top cap which is too small, so thought I'd ask here for more specifics.

Here are a couple of pics... Thanks!

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Ok....what you have here is the exception. That cap is specifically designed to work with that stem and it's ability to adjust the stem angle through the use of shims. You will have to replace the top cap if you replace the stem. And other top caps will try to angle the bolt in a weird way if you use it on top of the stem you currently own.

Ahh. That one is not concentric so the stem can be put in two different positions without flipping it.

I don't think there are aftermarket caps for that.

Much appreciated! Good to know, have a great day and thanks again!

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I had a similar specialized stem on an old bike. Because it has a shim attached that allowed it to be used in + or - angles as well as 8˚ or 17˚ (along those lines) the top cap is special because it needs to match up with said shim by angling itself. Hope that makes sense.

Having zero experience with shims, is that why it has the + and - marked on it? Thanks!

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The shim is a little metal insert inside your stem. It allows you to change your stem from positive to negative angle (leave the shim where it is and flip the stem) or to change the angle of your stem by spinning the shim 180˚. The +- topcap just allows this shim to work. The top cap angles itself which is necessary on this stem. If you change stems you can just get a normal top cap.
Hope that makes sense.

JScycle wrote:The shim is a little metal insert inside your stem. It allows you to change your stem from positive to negative angle (leave the shim where it is and flip the stem) or to change the angle of your stem by spinning the shim 180˚. The +- topcap just allows this shim to work. The top cap angles itself which is necessary on this stem. If you change stems you can just get a normal top cap.
Hope that makes sense.

Yes perfect sense, and I do appreciate the explanation!

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