headset bearings keep coming loose
Hi Guys
Changed my bearings this weekend for new as had a bit of judder under braking. i have had to retighten them a couple of times this year.
Bottom bearing was shot and replaced like for like.
These are what i fitted:
http://www.jejamescycles.co.uk/kinetic-headset-bicycle-bearing-1-1-8-mh-p08h8-id84125.html
i measured the old and they are exactly the same.
After i fitted them i made sure they were tight but not overly so and then torqued the stem bolts. After 13 miles yesterday i started to get the judder again. i stopped and retightened the headset but upon returning home i noticed that there is a gap top and bottom of the headset.
It wasn't there before as i have pics of the bike when i bought it, so what could be amiss here?
Top
Bottom
Any ideas. All looks ok when i strip it and i rebuilt it as it came off.
Changed my bearings this weekend for new as had a bit of judder under braking. i have had to retighten them a couple of times this year.
Bottom bearing was shot and replaced like for like.
These are what i fitted:
http://www.jejamescycles.co.uk/kinetic-headset-bicycle-bearing-1-1-8-mh-p08h8-id84125.html
i measured the old and they are exactly the same.
After i fitted them i made sure they were tight but not overly so and then torqued the stem bolts. After 13 miles yesterday i started to get the judder again. i stopped and retightened the headset but upon returning home i noticed that there is a gap top and bottom of the headset.
It wasn't there before as i have pics of the bike when i bought it, so what could be amiss here?
Top
Bottom
Any ideas. All looks ok when i strip it and i rebuilt it as it came off.
0
Posts
The first is always notorious of coming loose.
Further check if the topcap does not rest on the steerer when tightened.
Gaps look OK to me.
less likely...
steerer and/or stem damaged
head tube and/or bearings and/or spacers are getting shorter
the top cap and expander are only there to preload the bearings before you tighten the stem, once the stem is tight they have nothing to do in that respect (ok, the bung may give the steerer a bit of support against stem clamping force, but that's a sideline)
so, remove stem, clean clamping surfaces of stem/steerer of any grease/dirt/whatever, refit, preload (1 to 2Nm is enough on the topcap screw), clamp enough that it doesn't slip, ride
less likely...
steerer and/or stem damaged
head tube and/or bearings and/or spacers are getting shorter
the top cap and expander are only there to preload the bearings before you tighten the stem, once the stem is tight they have nothing to do in that respect (ok, the bung may give the steerer a bit of support against stem clamping force, but that's a sideline)
so, remove stem, clean clamping surfaces of stem/steerer of any grease/dirt/whatever, refit, preload (1 to 2Nm is enough on the topcap screw), clamp enough that it doesn't slip, ride
Just to be clear, the top of the steerer tube needs to be at least 3mm below top of the stem if there are no spacers above it, or 3mm below the top of the upper spacer if there are.
And the expander bung needs to be fully tightened inside the steerer so it won't slide up as you tighten the top cap.
With the stem clamp bolts undone you just tighten the nut in the top cap enough to eliminate any play in the headset. This isn't very tight at all. Check for play by holding the front brake on and trying to rock the bike back and forth; you'll feel knocking if it's still loose. Once you've eliminated play you tighten the stem clamp bolts alternately / progressively. Once the stem is clamping the steerer you could if you wanted remove the top cap, bolt and expander bung; it is not serving any useful purpose any more - apart from keeping rain out of the steerer.
If your headset is loosening it can only be that the stem is slipping up the steerer.
Not quite true, It stops a carbon steerer from being crushed when the stem is tightened.
This could be the most likely reason. I recently changed over the headset on my winter bike,a Bianchi Via Nirone.
The headset that was originally fit is no longer made so I got the closest to the original which was an FSA No.8B Orbit. I tried to fit the whole headset complete but it created the same symptoms mentioned. I eventually only changed the actual bearing and kept the origianal seals and star fangled nut in the fork. Problem solved. I couldn't even use the new top cap as it was a lot flatter than the original and thefore didnt have the 3mm gap as required.
http://www.parktool.com/blog/repair-help/headset-standards#article-section-7
get yourself a Vernier - well worth the money and measure your orginal bearings as I reckon you have mismatched the bearings along the line.
Riding along with a dodgy headset in any season aint recommended.
I'm gonna have to strip it to check as it could be that giving me the grief. I'll post back when i get to it.
currently riding the winter hack,old holdsworth steelie, and boy i'd forgot how heavy it was!
bearings side on:
See pics if i put the collar into the new bearing it sits higher into the bearing which is where the gaps appeared.
Old
So from what i can work out i have:
1-1/8" Diameter Bearing
Internal Dia: 30.5mm
External Dia: 41.8mm
Depth: 8mm
Chamfer: 45 / 45 Degrees one of these is wrong.
i'm guessing i need a 36/45 bearing with the other measurements the same. Just done some searching on the net and it would appear that a 36/45 bearing in 8mm is not a common thing so could it be 45/45 - how i could check these angles?
Also see pic of top cap removed - is this is enough of a gap to give good tension?
where do i set top cap on threads before fitting
at top:
or at bottom of thread:
cheers in advance
Also see pic of top cap removed - is this is enough of a gap to give good tension?
[/quote]
With that steerer you need at least a 10 mm spacer on the stem> problem found.
With that steerer you need at least a 10 mm spacer on the stem> problem found.[/quote]
Hi. There is a 10mm spacer I just haven't shown it.
You may need more than a 10mm spacer on top of that stem.
It depends on how the topcap fits as some go slightly inside of the steerer.
Do you know how to fit that top cap?
That is an expander and topcap in one setup.
Set the cap on 3 or so turns and then tighten up the smaller diameter allen key deep inside to expand the collars. Once this is tight use the larger allen key to fit the very top cap and set the preload.
Then as said before, hold the front brake on and rock bike back and forth, if there is movement or a knocking noise, tighten until it disappears. A good way to do this is to put a finger accros the headset join and feel for motion.
If you cannot remove the movement then you need to place another small spacer under or above the stem to create a bigger range of movement for the topcap to set the preload.
Expect a small amount of settling after the first couple of rides, so check and readjust as necessary.
Fitting the bung- ensure there's no grease inside the steerer.
Place the top cap only a few turns on the thread-to ensure it doesn't bottom out.
After stem is in position with top spacer-insert bung.
Tighten the inner bolt on the bung using a small hex (4MM ?) passed through the top cap.
Adjust top cap using larger hex (only enough to remove play)
Tighten stem.
Basically as above ^^
one thing i have learned is that the top cap has a hex fitting for tightening, i never knew that was there!
Very few people do. They assume tightening the top cap expands the bung when all that does is drag the bung up to the top cap (at which point the bung will expand a little, but isn't applying any preload to the bearings). Judging by the number of comments on forums like this and in reviews on retail sites like ChainReaction it appears to be a common misconception.