Low stack upper headset bearing?

So, as you can see, my stem is pretty slammed, and I use a “sandlebar”. I really like this sandlebar and want to keep using it, but I feel like I still could go just a couple mm lower in front.

When I first got the frame and built it up, I ordered a Slam That Stem 2mm stack dust cover (pictured). This did not work, as it could not cover the headset bearing and also come even close to the head tube. I did find another aftermarket dust cap that reduced the stack considerably compared to the stock dust cap, but again, at 4mm stack from this cover, the front end still feels just a hair too tall.

The problem is, on the Aethos, the upper rim of the headtube actually sits lower than the headset bearing by a few mm, as shown below. So, from what I can tell, this 4mm dust cover is lowest stack dust cover I can actually use, unlesssssss… there is a lower-stack upper headset bearing that could replace the current bearing, thus eliminating the gap from the upper rim of the headtube to the top of the bearing, and enabling me to truly slam the stem just a couple mm above the HT.

Has anybody ever been in this situation, or heard of an integrated upper headset bearing with a lower-than-normal stack height? I have not disassembled the front and removed the bearing to measure its stack, but I imagine it’s the same as every other upper hs bearing Spec uses on their road bikes.

Worst case I just go to a separate bar and stem with a -8 or -10, but that would be kind of shame because this Alpinist looks rad gives the bike a really nice ride quality up front…

Thanks!

Not sure if it will fit the Aethos, but I use the Cane Creek SlamSet which is as low profile as I’ve seen!

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That looks pretty slammed already. Will going any lower really make you more aero? The old Jurassic Park line about thinking if you could, not about if you should, comes to mind. Check in on the “riding in the drops” thread about position and fit options…

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Yea, it’s muy slammed. I probably need a -8 or -10 stem. Hard to know how a bike will fit until you ride it, and I got a sweet combo deal on the frame + sandlebar, so here we are. As far as aero, I used to ride a Venge, don’t miss it, so really not about aero at all. It’s more about how the fit feels. I can ride in the drops easily, but I think I am missing a teeny tiny bit of leverage in all the positions, mostly the tops and drops. I noticed quite a big difference going down 6mm from the stock dust cover to this one, so I imagine it will be again better to drop it a hair more, if I can.


Do any mechanics familiar with Specialized know if this is the correct spec of upper HS bearing? Thanks!

Forgive my ignorance in terms of nomenclature, but in my parts a different language is used to cover the same things, so, just using what I know, in simple terms, isn’t the basic problem that the upper headset bearing is too tall? Since these bearings come in heights of at least 6mm to 9mm (I’ve got those in my box), isn’t the problem simply one of finding a shorter bearing? And, as for the top headset cover, that too comes in various configurations, some allowing space to partially fit over the bearing, some flush with the bearing, so forth. Personally, I would look for a shorter bearing and work from there (again, apologies to the pros if I am way off target here).

Yes! You’re right on, macnmaze. That is a much better and simpler way of saying it. I just don’t know that much about bearings, so I am hoping to find something that is very short AND for sure compatible with my bike, so I don’t have to run around too much to get it figured out.

Specialized are IS42 uppers.

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One other thing to keep in mind is that IS numbers refer only to the outer diameter of the bearing–bearings will also differ by inner diameter, the slope or angle of both the inner and outer edges in some cases, but most importantly, as mentioned above, in height–often times you will see bearings described like this: 11/8" | IS42/28.6 | OD:41.8 x ID:30.5 x H:8 x A:45°, where the key factor for you is a lower “H” number, and possibly a different angle depending on the configuration of the upper part of your headset.

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I read something about headset bearings on a great website called cyclingtips.com

It may help.

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So, there’s a mixed bag ending to this story. There is no bearing with low enough stack to slam this stem any lower. The SlamSet bearing did have a lower stack, but the difference in the stack was confined to the funneled portion of the bearing, so once it was actually installed, the same amount of bearing still protruded above the rim of the headtube. The good news is that I got a nicer-looking dust cover with the bearing, learned how a compression plug works, cleaned my lower bearing which was pretty nasty, and then just bought another bike to get in a more aggressive position when I want to LOL. Allez! !!Allez!

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Much as I like an Allez, would a new bar/stem arrangement not have been more, err, economical??

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N+1, @Mintaerobars , shut up and let him ride it.

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Tbf I’ve seen worse justifications for N+1.

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Yea, this was totally tongue-in-cheek. I just really like this bike, and have about 50 other N+1 excuses catalogued for it.

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N+1 is a REASON, not an excuse.

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Wait, can’t you just get a 17 or 20 degree stem?

for lower handlebar, syntace flatforce stem will get you 20 mm lower.