tech question re: Specialized Pro Set stem

[eddief]

These are the stems that come with one or more inner sleeves that go on the fork steerer first and then the stem on top of that. The sleeves are made so they can be turned and by doing so each different position gives more or less rise adjustment to the stem. I know all those things.

My question is wether or not, due to the adjusting sleeve, does the installation require their special top cap or will any top cap work? And...can you install a spacer under the top cap and on top of the stem?

[rnhood]

The best fit is the top cap right on the stem but, it will work with a spacer also. its just not quite as clean of a fit, but it is perfectly acceptable.

The sleeve is inserted from the bottom of course, and the top cap is turned so its polarity sign is aligned with the stem angle ("-" for negative rise, "+ for positive rise). But this is only for indication, its not necessary to tighten it like this. Once the two stem screws are tightened, the top cap doesn't do much except maybe block out water.

[kenw]

As mentioned above, aesthetically works best with Specialized top cap,
but a spacer and your favorite top cap work also.

[chismog]

I'm going to go against the grain and say that it depends on the shim you use.

The 8/16 stem is a natural 12 degree. Thus if you use the 12 deg shim, it is actually a straight shim and it doesn't matter which way you turn it. With this shim you can use an ordinary top cap and stack a spacer on top. The straight shim provides 0 degrees of adjustment to the natural rise of the stem.

However, if you use the 4 or 2 degree shims, to generate angles of 10/14 or 8/16 degrees, what you will find is that the stem now sits funky on the steerer. This is where the special ProSet top caps come into play. If you try to use a regular top cap you may not be able to get the headset preload right, because the bolt won't line up correctly and won't press the cap evenly on top of the stem stack. Trying to stack a spacer on the top of the stem with the 4 and 2 degree shims also doesn't work. The spacers stack like the leaning tower of Pisa and leave a gap.

So... 0 degree shim to give a 12 degree angle = OK. Use whatever top cap or spacers you like on top.

2 or 4 degree shim... All bets are off and I think you'll need the special top cap, and not be able to put a spacer on top of the stem. Specialized would probably say "Spacer on top? That's why we made the adjustable rise stem!".

Hope this helps.
C

[Gummee]

I'm trying to get my Roubaix to fit like a Tarmac (don't ask) and have a total of -19deg down on the stem. Have all the spacers on the top of the stem 'cause while I'M trying to be Ricky Racer, the next guy down the line prolly won't be and I don't wanna limit myself to whom I can sell this bike/frame.

Seems to be OK, as in flat, in my situation.

I did try one combo that was sitting funny, but I don't remember which one that was.

Specialized specifically sez 'no spacer on top' in their destructions. No, I didn't listen. (see above)

M

[eddief]

i would probably use the 12 degree stem in the neutral position, so my top cap issue would be non issues.