After riding my Specialized Chisel 2018 all winter, the headset bearings need replacing. Unfortunately the lower bearing is an unusual type which doesn’t seem to be available anywhere. I emailed FSA who replied as follows:

Thanks for your e-mail, please find the bearing details below for this headset. The upper is available however the lower is not so I would recommend packing with loose BB’s and grease as this will increase the number of ball bearings.

Upper

160-1657 Bearing Pig Upper Ball Bearing (5/32×20, MR013)

Lower

BB size 3/16”

I’ve serviced a few cup-and-cone style hubs, so I’m not afraid of loose ball bearings, but this sounds a bit weird. I’m a newbie when it comes to headsets though!

I’d be interested to know if anyone with more experience than me thinks this is a feasible approach. I’d much rather spend a few quid on some ball bearings than buy a new headset plus all the tools needed to install it (since I’m trying to do all my maintenance myself now).

I say that’s a bad idea

We use this guy for all our Specialized headset bearings.

https://www.ebay.co.uk/itm/Specialized-Fit-Headset-Bearings-1-1-8-1-5-Integrated-Tapered-Bearing-Kit/301804085047?hash=item4644ecdf37:g:KMAAAOSwHsRYDifu&redirect=mobile

What size is the bearing? (ID/OD/H and both angles?)

It’s an MH-P25 which I believe is 40mm x 52mm x 6.5mm / 45° x 45°.

You can get MH-P25Ks easily (40mm x 52mm x 6.5mm / 36° x 45°) and also MH-P16s (40mm x 52mm x 7mm / 45° x 45°) but not MH-P25s. Neither Wych Bearings nor Kinetic Bike Bearings has been able to help.

Eh? You can’t just replace a cartridge with balls: the races are part of the cartridge.

Or have I got the wrong end of the stick?

Are Specialized not legally obliged to make spare parts available for a number of years?

Try Pearce in Ludlow. They carry a decent stock of Specialized spares.

Eh? You can’t just replace a cartridge with balls: the races are part of the cartridge.

That’s what I was thinking!

This might be worth a try…

https://www.superstarcomponents.com/en/type-2-headset-bearings-1-5-or-tapered-45×45-degree-x1.htm

same dimensions, only 0.5mm taller.

edit: Just read that you’ve already seen that size.

Do they mean popping the existing bearing open and replacing the bearings and retaining ring or do they mean remove the whole bearing and run on the cup?

I’d imagine it’s the first, so why not? I’d be happy doing that. After all, if it doesn’t work, it will mean a new headset. That’s what you’re looking at anyway as you can’t get the bearings.

Just replace the lower headset – its only a bearing and a crown race.
The tricky bit of that bearing is the inner angle, easily solved by fitting a different race, only tool you would really need is a flat blade screwdriver and a bit of care.

Id fit a cane creek forty personally. Theyre not sealed at all well though as youve found out, strip and regrease them every couple of months.

Personally id just remove the bearings seals, flush the bearing out with some white spirit/ipa etc..

See if the bearings are pitted/damaged, if not then re grease and refit seals

Done this to loads of bearings over the years and never been an issue

Other option is to look on the side of the bearing and you should be able to see the dimensions printed on it, type them into Google and see what comes up

Or just use Cane Creek’s headset finder

https://blue.canecreek.com/headset-fit-finder

Putting your bearing number into eBay pulls up a few so they are easily available. I have been and checked our bearing box in the garage and all our spares are 7mm deep even the ones that have come via specialized and the old originals that we have replaced but saved just in case. Ours are carbon frames and the bearing sits straight up to the carbon.

so I would recommend packing with loose BB’s

Just a slightly badly worded way of saying what Onzadog suggested, I reckon. Repack the existing bearing.

Have you removed the bearing to check and measure?

You may well be able to fit a MH-P16 without it changing anything, or just moving the fork down 0.5mm. Depends if the 0.5mm is in the chamfer or vertical, and if the bearing seat is cut for an exact fit, or if the chamfer is deeper than the bearing (common).

If the bearing races are corroded new balls wont help.

If I read the original recommendation correctly, it’s to dismantle the cartridge bearing itself, remove the cage and to reassemble with a full compliment of new bearings, not to simply dispense with the cartridge bearing and replace with loose bearings with no race surfaces – that would be utterly insane.

MH-P16s (40mm x 52mm x 7mm / 45° x 45°)

should fit and spin fine.
it’ll just be 0.5mm taller. meaning a 0.5mm gap under the headset top cover. without seeing the top cover it might be possible to seal that gap with a suitable thin plastic washer (cut to size)
it may also be possible to file half a mm off the inner portion of the top cover so it sits lower.
again without seeing any of it difficult to say.

It’s the bottom bearing, not the top one 😉

The 0.5mm is in the height. It’s the bottom bearing.

Thread resurrection! Was this ever resolved?

I’d like to bludgeon the specialized crayon holder with a pair of bombers for not using a standard bearing.

Don’t get me started on the campy top bearing they insist on using with the woeful sealing!