Stem issues

DS2013

I decided to lower my stem by one spacer this evening. This is the first time I have adjusted the stem height on a road bike and as usual for a first time it was a little more difficult than expected as the top cap fell apart on me and I had to get some of the parts back out of the stem. When I finally finished I found there was a slight rocking of the forks. I assume I have not tightened something properly, any advice on what the procedure is from here rather than me having to spend hours messing about. Thanks.

onthefringe

DS2013 wrote: »

I decided to lower my stem by one spacer this evening. This is the first time I have adjusted the stem height on a road bike and as usual for a first time it was a little more difficult than expected as the top cap fell apart on me and I had to get some of the parts back out of the stem. When I finally finished I found there was a slight rocking of the forks. I assume I have not tightened something properly, any advice on what the procedure is from here rather than me having to spend hours messing about. Thanks.

You've described you compression bung dissembling itself..
Did you reassemble ?
And then did you compress the fork?
Also when you removed the spacer is there adequate room for the cap to compress against the stem?
It is simple ...but only f you've an understanding of it

Cee-Jay-Cee

Also, tighten down the top cap first then tighten the pinch bolts on the stem faceplate.

omri

onthefringe wrote: »

You've described you compression bung dissembling itself..
Did you reassemble ?
And then did you compress the fork?
Also when you removed the spacer is there adequate room for the cap to compress against the stem?
It is simple ...but only f you've an understanding of it

What he means is - with spacer above the stem or without the steerer tube has to be 2-3mm lower than the top of spacer/stem - so that when you put the cap and tighten the bolt the cap will push down on the spacer/stem while the bolt will pull the fork up (bolt goes into the star nut thats inside the steerer tube) - and thats how you compress the headset.

If your steerer is higher than the spacer/stem edge the cap will simply push onto steerer which gives no compression to the headset. And everything will rattle. You need to compress the headset by tightening the cap bolt and once you're happy with the tension (can't be too much) then you tighten the stem bolts. And then just hold your front brake and push forward to feel if there is any play in the headset. If you can't feel anything and fork turns easily then happy days, job well done.

DS2013

Thanks for the replies. I did get the pieces out of the stem and reassembled it all. Sounds like my issue is not putting enough to downward pressure on the stem/forks and tightening the cross bolts before fully tightening the top bolt. I will double check that there is some stem showing above the spacer when I put it back (as far as I recall there was some). Hopefully five minutes this evening will solve the issue.

Cee-Jay-Cee

DS2013 wrote: »

Sounds like my issue is not putting enough to downward pressure on the stem/forks and tightening the cross bolts before fully tightening the top bolt..

The reason it's loose is because your doing it the wrong way around. You tighten the top cap FIRST. it's the top cap that compresses down the stem effectively pulling the fork up in to the steerer tube. Then once it's tight you tighten the stem faceplate bolts.

Tip: tighten the top cap till you can no longer turn the spacer below the stem. If you can turn/spin the spacer, it's not tight enough.

Special Circumstances

As above top, cap needs "just enough" tension to compress things. Bearings will be too tight or cap will break if you go too gorilla on it.

check_six

Cee-Jay-Cee wrote: »

The reason it's loose is because your doing it the wrong way around. You tighten the top cap FIRST. it's the top cap that compresses down the stem effectively pulling the fork up in to the steerer tube. Then once it's tight you tighten the stem faceplate bolts.

Tip: tighten the top cap till you can no longer turn the spacer below the stem. If you can turn/spin the spacer, it's not right enough.

This is good advice. The stem bolts do all the work once the stem has been set up correctly. The Top cap is there to put on the initial compression. I had difficulty on my forks as they were carbon and instead of a star nut they had a plastic expander thing with a reverse thread. I wasn't putting the correct torque on the expander and the top cap kept pulling it out of the fork and not giving enough compression for the stem bolts to be set up correctly.

In theory, once the top cap has been set and the stem bolts tightened in place, the top cap is no longer doing any work holding the fork together.

To test, turn the front wheel at 90 degrees to the frame and see if there is any movement in the headset when you try to move the bike forward.

Also, beware of damage to the ball bearing races (at top and bottom of headtube), I had this difficulty on an old MTB and they had to be replaced (cost for the part was sub €1). This can also give a lot of headset voodoo!

DS2013

Thanks for the advice. Followed the instructions and it is much better. There is still a little movement but that may just be the natural movement of the forks. Will check with guys from workshop in LBS when there next week.

Alek

There is no such thing as natural movement of the forks, except for rotation

DS2013

Very true. The movement I am talking about is very very slight but it is on my mind now after taking the headset apart.

Cee-Jay-Cee

There should be no movement. It should be rock solid.

Juan More Time

Any spacers you remove from beneath the stem must now be installed above the stem, unless you intend cutting the steerer tube of course...

devonp

anyone got experience of the Acros system headset used by Canyon?
seems from their youtube videos(acros) the stem bolts are tightened to torque before tightening the small screw in the headset ??

DS2013

Cee-Jay-Cee wrote: »

There should be no movement. It should be rock solid.

There is a slight movement. I am wondering if I put a washer back in the wrong place. When I was putting it all back together.

DS2013

Juan More Time wrote: »

Any spacers you remove from beneath the stem must now be installed above the stem, unless you intend cutting the steerer tube of course...

I put the spacer above the stem, no plans to cut the steerer tube at this stage.