I just ran into a problem I can’t get my head around.

I’m putting together a hack bike based on a second hand Inbred 29er. The frame came with an old Syncros FR1 headset and I now can’t seem set it up to work properly with the fork I was planning to use (1 1/8” straight steerer x-fusion slide). When I tighten the headset I get really bad binding and it looks like the steerer makes contact with the inside of the lower cup. Bearing, cup and crown race look just fine bit it’s like the steerer is slightly too wide (or the cup above the bearing too narrow).

I know the slightly wider base of the x-fusion steerer (for seating the crown race) is taller than on any other fork I used (RS, Zocchi) but the fork worked just fine in at least two other frames. Alternatively the headset is shot but everything looks OK as far as I can tell.

Any suggestions or thoughts would be much appreciated. Of course I could just fit a new headset but that would go against the low-budget nature of this project 🙂

Cheers from Sweden
/Johan

I’ve had this exact problem with a RS Sid and Acros headset, and again with a Fox 32 and a Diatech one.

Both in different frames I might add, and in both cases the tapered bit of the steerer was making contact with the inner face of the lower cup.

A tiny bit of filing sorted both of them but its annoying when it happens, it seems to be just a case of a slightly out of tolerance part in some circumstances.

Aha, there you go. Thanks for sharing amedias. I’ll have a closer look at it and maybe try some filing. I reckon filing the headset cup (if I can get to it) would be better than filing the steerer, no?

/Johan

Obviously from your description it *sounds like* you have the same thing going on, but make sure you do double check it’s not something else before you go modifying bits of kit!

I even went as far as taking the headset out of the frame, and then checking where the contact was as I slid the cup (with bearings removed) down onto the steerer as the first time it happened I was convinced it couldn’t be that, but sure enough, contact occurred with the cup still about 1mm from where it should be once bearings and crown race fitted.

Check there’s no burs or other damage to the inner face of the cup that could be contacting as it could be that rather than it being a tolerance thing.

and yes, I filed the headset cup inner edge (with bearings removed!) as it only needed a tiny bit taking off to clear, I wouldn’t file the steerer.

Many thanks for detailed input. Makes sense.

Cheers
/Johan

Mission accomplished!

This morning me and mr Dremel had a chat with the lower cup and the result seems very satisfactory, a smooth (enough) running headset.

Thanks again to amedias.

/Johan