New stem - now wobbles

mikkybgs

Hi, I've tried to research this problem but it seems it could be down to a number of reasons and as I'm still getting to grips with maintaining my bike I thought I'd bring my situation to the table for advice.

I got a new stem for my 8.1 Decathlon Rock Rider seen here: viewtopic.php?f=20005&t=12857201&start=20

When I fitted the new stem I took out one of the two spacer rings becuase I thought with the rise of the new spacer one would be enough. (I think I have mis-understood the job of these spacers)
Once I tightened everything back up I nothced there was a little bit of play in the (I think it's called...) the headset. When I put on the brakes and turn the front wheel at a right angle to the bike and rock it forward and back there is movement here, where there was none before.

I took of the new stem and re-fitted the second spacer but now there is still movement.

Is it a case of tightening something that I'm not?

nicklouse

if the stack height is the same or less for the new stem you will need to put them back and maybe add spacers.

they can go no top of the stem as well as under.

they allow the top bolt to appy the preload to the bearings.

have a read.

you need a gap

.blitz

Think of the stem as a spacer like the one you took off. The top cap tightens against the stem and the other spacers to take the slack out of the headset bearings. As above, you need to make sure the top edge of the stem stands proud of the steerer tube otherwise the top cap will tighten against the steerer tube and do nothing. You can add a spacers above or below the stem

Make sure the stem clamp bolts are loose, then tighten the top cap until the forks turn easily without any play. Align the stem and tighten the clamp bolts.

mikkybgs

Thanks, that's great!

I completely misunderstood the system here.

Re fitted the spacer and tightened the top cap and job's a good 'un!

slowondefy2

Careful you don't tighten the top too much. You only need just enough to hold the headset together, then you tighten the stem onto the steerer. It's really easy to over tighten the starnut.

mikkybgs

slowondefy2 wrote:

Careful you don't tighten the top too much. You only need just enough to hold the headset together, then you tighten the stem onto the steerer. It's really easy to over tighten the starnut.

I'll keep an eye on it, thanks!