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Hi, I built up a mtb hardtail which has a tapered headset (frame is a thompson xc-7000)
I used it and noticed a bit of rattling in the front end. I have opened it up as the headset felt slightly loose, everything was correctly tensioned so I took the forks out to check the lower bearing and crown race and noticed the crown race was sitting very loosely? It is the spilt type but is sitting so loose it is rocking a little which explains why there is that loose feeling when tensioned. The headset is an ITM 1 1/8 - 1 1/2, I am wondering if I would be better sourcing a single piece (without split) crown race or try ordering a replacement of the version I have.
At the moment bike is out of action so any advice be helpful to proceed.
We are talking about the race that fits to the lower fork here, and not the frame, right?
I think I would be replacing the complete headset with a reasonable quality new one. If still loose, then you clearly have wear to the lower steerer. If not too bad then you could clean up and use a bearing retaining fluid or, possibly, shim with some very thin aluminium.
The tapered nature of the bearings does close up a split race to some extent, but they should be a snug fit on their own before any compression.
Thanks for the advice, Yes it is the race that fits onto the fork steerer tube. I have always used non spilt crowns before and had to work hard to fit them on sometimes with pvc tubing. In this case I am struggling to remember how tightly the race fitted onto the steerer. Now it is clear that there is an issue there with the loose fit yes, it will need a new race at the very least. I have a complete brand new FSA Orbit c-40 Integrated headset. Ideally I wanted to fit it right away. The stumbling block is the crown race for that is going to need pressing on and that means stripping the bike forks off and getting it done somewhere. I was looking at trying another split race but want to make sure it will work. I have read a lot cut the race themselves and it is now issue if done properly but having had this issue with the split one on this itm headset it ha put me me off them slightly.
A split crown race should work fine if it's sized correctly, they make installation and removal much easier than ones without a split. The crown race shouldn't need to be very tight to the fork steerer as the taper of the race and the lower bearing should mean they sit nicely together once the headset is tightened down
Yes, i know what you mean. I have had another look tonight and the steering just feels slightly stiff with resistance. I had blamed the crown race as I had repeatedly tampered with the top half and could find no problems but I am now thinking the headset is maybe the issue? Both upper and lower bearings feel fine but when it's assembled, even before tensioning it does not feel slick and smooth when turning the bars. I have a C40 fsa headset and may try installing that complete unit or even sourcing an alternative. Very strange as I have had a lot of these all fine for many years on my 1 1/8 straight steerer bikes but this does not feel good.
Is the top dust cover binding on the headtube/top bearing cup?
A shim will prevent that
If you are anywhere near Marple, I'm happy to help out... plenty of time on my hands at the moment!
I always heat the lower race before dropping it on and letting it shrink fit.
gently hold it with molegrips and warm over a gas stove/camping stove/blowtorch etc.
I did think a bit back that it was to do with the top bearing cover, it is a ITM headset. I switched it to a different bearing cover (Ritchey WCS) and it did move more freely and felt better.
I did notice for the 1 1/8 version of this headset which I also have for a road bike, a shim was included, do you sometimes need to use a shim on an integrated headset, on the other FSA C40 I fitted there was no issue but this sounds worth a try, it will go on top of the compression ring I take it and then place the bearing cover over that right?
Exactly that