Fitting a stem - tightness question

Not Responding wrote on 21/10/2006 11:54 +0100:

Quoted message said:

I've just fitted a new, shorter stem to my bike. I think I've done
everything right; handlebars approximately centred (wish I'd marked it
before taking the old one off) and bars and wheel aligned to my (low)
standards of accuracy.

Outstanding question. I've tightened the nut at at the top of the
steerer as hard as I can but the spacers are still loose enough to
rotate. There's no vertical play and I can't detect any fore-aft
looseness on the whole set up. But I'm still a bit concerned that it
might be too loose.

Any tips or reassurance?

You shouldn't need to tighten the top bolt very tight. Its just there
to hold the assembly together while you tighten up the bolts on the stem
itself. Other than that it sounds OK. The best check is to hold the
handlebars with the front brake on and then rock the bike back and
forth. If it is loose you will feel the bearing rocking through the
bars. Doesn't work as well with suspension forks

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

in message <[email hidden]>, Not

Responding (') said:

I've just fitted a new, shorter stem to my bike. I think I've done
everything right; handlebars approximately centred (wish I'd marked it
before taking the old one off) and bars and wheel aligned to my (low)
standards of accuracy.

Outstanding question. I've tightened the nut at at the top of the
steerer as hard as I can but the spacers are still loose enough to
rotate.

That's because the bolt on the top doesn't affect the spacers. The two
bolts on the back of the stem do. And don't overtighten the bolt on the
top, because you'll just pull your star fangled nut out.

Procedure:

(1) loosen all three bolts (the one on the top and the two on the back of
the stem;

(2) tighten the one on the top until everything is snug and there is no
play in the headset bearing - this is not very tight;

(3) check that the handlebars are parallel to the axle of the front wheel;

(4) tighten the bolts on the back of the stem, properly tight;

Job done.

Quoted message said:

There's no vertical play and I can't detect any fore-aft
looseness on the whole set up. But I'm still a bit concerned that it
might be too loose.

Any tips or reassurance?

It's quite OK for the top bolt to be loose. Indeed, it's OK for it to be
missing altogether, provided you have some sort of a bung over the hole.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

I shall continue to be an impossible person so long as those
who are now possible remain possible -- Michael Bakunin

Not Responding said:

I've just fitted a new, shorter stem to my bike. I think I've done
everything right; handlebars approximately centred (wish I'd marked it
before taking the old one off) and bars and wheel aligned to my (low)
standards of accuracy.

Outstanding question. I've tightened the nut at at the top of the
steerer as hard as I can but the spacers are still loose enough to
rotate. There's no vertical play and I can't detect any fore-aft
looseness on the whole set up. But I'm still a bit concerned that it
might be too loose.

Any tips or reassurance?

Reassurance: As long as the stem is on properly and the headset adjusted
reasonably well, it'd be safe to ride the bike with loose spacers and no top
fastener* at all. Even with a properly adjusted headset it's sometimes
possible to turn the spacers by hand with a firm grip.

Tip: Try a different top cap or an extra spacer if any spacers /above/ the
stem are loose enough to rattle.

* star nut or bung, top bolt & cap - all the vertical stuff that goes in the
top.

~PB

On 21/10/2006 11:54, Not Responding said,

Quoted message said:

Outstanding question. I've tightened the nut at at the top of the
steerer as hard as I can but the spacers are still loose enough to
rotate. There's no vertical play and I can't detect any fore-aft
looseness on the whole set up. But I'm still a bit concerned that it
might be too loose.

You didn't tighten the stem up *before* tightening the top nut, did you?

--
Paul Boyd
http://www.paul-boyd.co.uk/

Paul Boyd wrote on 21/10/2006 14:10 +0100:

Quoted message said:

On 21/10/2006 11:54, Not Responding said,

Quoted message said:

Outstanding question. I've tightened the nut at at the top of the
steerer as hard as I can but the spacers are still loose enough to
rotate. There's no vertical play and I can't detect any fore-aft
looseness on the whole set up. But I'm still a bit concerned that it
might be too loose.

You didn't tighten the stem up *before* tightening the top nut, did you?

Another possibility is the top cap has bottomed out on the top of the
steerer tube which may happen if the steerer is too long or
alternatively there are not enough spacers fitted.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

Paul Boyd said:

On 21/10/2006 11:54, Not Responding said,

Quoted message said:

Outstanding question. I've tightened the nut at at the top of the
steerer as hard as I can but the spacers are still loose enough to
rotate. There's no vertical play and I can't detect any fore-aft
looseness on the whole set up. But I'm still a bit concerned that it
might be too loose

Quoted message said:

You didn't tighten the stem up *before* tightening the top nut, did you?

Nope. Got that bit right. Tightening the vertical bolt before the
horizontal bolts is about the extent of my headset knowledge, though.

in message <[email hidden]>, Simon Brooke

(') said:

in message <[email hidden]>, Not

Responding (') said:

Outstanding question. I've tightened the nut at at the top of the
steerer as hard as I can but the spacers are still loose enough to
rotate.

That's because the bolt on the top doesn't affect the spacers. The two
bolts on the back of the stem do. And don't overtighten the bolt on the
top, because you'll just pull your star fangled nut out.

Ooops! Sorry, I've just noticed who I was replying to. I'd have written a
much less snotty reply if I'd realised it was you!

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; 99% of browsers can't run ActiveX controls. Unfortunately
;; 99% of users are using the 1% of browsers that can...
[seen on /. 08:04:02]

In article <[email hidden]>

Not Responding said:

I've just fitted a new, shorter stem to my bike. I think I've done
everything right; handlebars approximately centred (wish I'd marked it
before taking the old one off)

Take a bit of string the length of the bars, fold it in half ...

Quoted message said:

and bars and wheel aligned to my (low) standards of accuracy.

Outstanding question. I've tightened the nut at at the top of the
steerer as hard as I can but the spacers are still loose enough to
rotate. There's no vertical play and I can't detect any fore-aft
looseness on the whole set up. But I'm still a bit concerned that it
might be too loose.

Any tips or reassurance?

Could be
[a] the new stem isn't as deep as the old one so the steerer is sticking
up too far - add a spacer under the stem.
[b] the nut has moved up the steerer so the plug is resting on it -
loosen the bolt a few turns and tap it down to reset the nut.
Most likely both - [a] stopped it tightening properly, so you
overtightened it causing [b].
The wedge ring in the top of the headset is probably holding the top
race where it was with the old stem - if you use it as it is it will
probably work loose.