Reducing the stack height of headset?

The bottom race/bearings of my headset sit about 8mm out from the frame at the bottom of the head tube. Is there a way to get the bottom, or indeed top race/bearings flush in the head tube by using some kind of integrated jobbie?

Frame is carbon on-one with tapered head tube.
Fork is tapered carbon
Headset is on-one.

I need to gain about 5mm back to accommodate the fork I’m trying to use.

I’ve researched changing stem, but can only really gain a few MM that way.

Hard to say – 8mm is a big stack on the bottom. A Cane Creek 40 is just 4mm for example. Do you know the SHIS numbers for your headtube?

On One carbon tapered frames are normally 49.9/50mm ish external lower and 44mm zero stack (for 1 1/8th or tapered steerer) or can take 44mm external stack (for 1.5″ or when using angleset) upper.

I don’t think you will get a zero stack lower cup for a 1.5″ or taper steerer in there. They normally need 55/56mm IIRC.

Why do you need to lose height? Steerer too short?

You can’t do it – you can run an integral lower cup but it would drop the front end and limit you to a 1 1/8th fork which you haven’t got. I’m also assuming you’ve never tried to remove the lower cup on a 456 carbon…..

30mm stem is a better option, if you’re already on a 30 mm stem with no spacers then you won’t get 5mm back.

It is because the steerer on a fork i’d like to use is too short

It’s currently running a 40mm stack stem, so i could maybe lose 3-4mm there. It’s tricky to know the dimensions of a stem tho’ as they dont list them stack heights on most items.

@bennpick – a Cane Creek 40 might just do it maybe? i’ll have a look at that.

@andyl – so, could i get a ‘flush’ or zero stack for the top of the headset? where the fork is 1-1/th? the stack on the top part of the existing headset is about 6-7mm right now.

All these standards are getting tricky!

On One make a 35mm stack height stem. Currently running one on my Sherpa for the same reasons.

pop into your local machine shop and ask if they can knock up one of these?

@letmetalktomark –
which one is that please. I’ll check it out.

SCrap that….
is it this one ?

stem?

It’s currently running a 40mm stack stem, so i could maybe lose 3-4mm there.

The Funn Funnduro stem has a stack height of only 30mm, it’s not expensive either and a decent stem.

I asked a similar question as you re low stack stem, the ragley stubbing stem is 30mm stack height

Lardman – just had a look. Seems they don’t list the one I bought now ( CNC I think )

sorry, should have been clearer. It’s for a gravel bike and stem length needs to be around 90mm.
Most of the low stack ‘stubbies’ are only up to 40-50mm ish length i believe. Also, i was trying to keep the weight down where possible.

thanks for the suggestions tho’

Hard to say – 8mm is a big stack on the bottom. A Cane Creek 40 is just 4mm for example. Do you know the SHIS numbers for your headtube?

Came creek 40 in EC lower is a 12 mm stack height? You’ve got 7/8mm of bearing depth in there to start with.

Ragley stubbing gives you options in 40/50/60mm length £40 from crc. Stack height of 30mm drops you 10mm without messing with the geo.

Edit: just seen your length requirements, truvativ team stem is low and long and a few others I.e. Easton carbon but they are all single bolt. If your talking purely gravel I’d look at those, not sure if I’d be confident giving one hammer on a trail though.

@nickdavies –

Do you know the SHIS numbers for your headtube?

errr…. i don’t even know ‘what’ that is!!!

truvativ team stem is low and long and a few others I.e. Easton carbon but they are all single bolt. If your talking purely gravel I’d look at those, not sure if I’d be confident giving one hammer on a trail though.

I’ll check those out ta.

BTW, did you used to live in Brighton? I know yours is not an unusual name, but used to ride with a ‘Nick Davies’ ?

I think i’ll head to my LBS and see what they can do about a lower stack top part to the headset, then ive found a few stems in 35mm stack. Between the two i’m sure i can get the reduction i need.

thanks all.

@andyl – so, could i get a ‘flush’ or zero stack for the top of the headset? where the fork is 1-1/th? the stack on the top part of the existing headset is about 6-7mm right now.

What frame is it and what size?

One thing you need to be careful with taper steerers is too little stack where the split ring that sits in the upper bearing and expands to take up the play is only in contact with the straight part of the steerer, not the tapered bit. Mk1 C456 frames in 16″ had a problem with the head tube being too short for rockshox tapered steerers.

You NEED an external lower cup as the bottom is simply not big enough diameter for a zero stack AND a 1.5″/tapered steerer.

For the top you should have a low stack unless you have the 16″ frame short headtube problem. This would be a couple of mm of cup protruding from the top of the head tube in which the bearing and the split rind sit and then the top cover of the headset before your spacers and stem. You can remove this top cover and run without (but keep looking after your bearings) or get a “slam that stem” (or whatever they call their website) top cover to save some height. 6-7mm sounds like you do have a low/zero stack upper but it still has some height because of the 2mm or so of cup lip and then 4-5mm of top cover so I doubt a new upper headset will solve anything and more a change of top cover or stem would be needed.

It’s an On-one Lurcher frame in large. So the headtube is on the longer side.

The stack height of the On-one smoothie mixer headset is about 10mm at the top. So, i reckon just swapping this out for a Cane Creek 40 would save me about 3-4mm and the rest i would get back from gaining 5mm lower stack in the stem.

i might look at the top cover thingy, as it is quite big. Maybe that ‘slam stem’ thing might be worth looking at.

Thanks for your replys tho’.