Stem Not Tightening Up

[MacB]

Ok, I've got a new stem, the FSA OS120 from On-One:-

http://www.on-one.co.uk/i/q/STFSOS120/fsa-os120-road-stem

and full details are here:-

http://www.fullspeedahead.com/fly.aspx?layout=product&taxid=113

I can't seem to get the stem to clamp the steerer properly. The stem is actually shimmed, it has a 31.8mm steerer clamp and a shim to fit it to the standard 28.6mm. Apparently this is to help prevent damage/crimping to steerer tubes, particularly carbon ones. When fitted I can still rotate the stem around the shim with minimal effort, it gets fairly tight but not good enough to be safe to ride. I've tried it on 3 different bikes with the same result, so it's not the steerer tube size.

However when I look closely there is a spacing washer on each of the stem clamp bolts. These limit how tight you can get the stem, they look to be about 2mm each. I can't find anything in the instructions but are you meant to remove these spacers?

I've not come across this before and am puzzled, I have sent a query to OnOne but they're not open til Monday. I was kind of hoping to use the bike tomorrow. The bars are all wrapped and fitted and this is the only 31.8 bar clamp stem I have, so I don't want to swap bars again.

 

[e-rider]

sounds odd, are you locating the 'split' in the shim in the correct place?

Most stem bolts have washers, I can't see how they would cause a problem - photos please (the 2 links show different versions of the OS120 stem.

It says it's for 1 1/8" steerers (no mention of shimming from 1 1/4") edit: OK the FSA site mentions it but it's a different stem to PlanetX site.

Do you have the 35mm stack, bolts same side version OR 40mm stack, one bolt each side version?

Bargain for £15

 

[e-rider]

If you are not using a carbon steerer tube then try locating the split in the shim in line with the gap in the stem

 

[MacB]

No they are the same stem, maybe just different incarnation, but details on FSA site are correct I think they've just got the stem bolts opposing now rather than same side as before. You can see the washer I mean clearly on the CRC site here, it's in the middle of the bolt between the two sides of the stem:-

http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=42437

Basically with the stem tightened as far as it'll go it still moves quite easily. Removing the washer would allow for further tightening but no doubt invalidate any warranty etc.

 

[e-rider]

No they are the same stem, maybe just different incarnation, but details on FSA site are correct I think they've just got the stem bolts opposing now rather than same side as before. You can see the washer I mean clearly on the CRC site here, it's in the middle of the bolt between the two sides of the stem:-

http://www.chainreac...9&ModelID=42437

Basically with the stem tightened as far as it'll go it still moves quite easily. Removing the washer would allow for further tightening but no doubt invalidate any warranty etc.

yes it's been updated - that's what I meant.

Never seen a washer in the middle before, and that's clearly what is causing the problem. I guess it's a nice idea to prevent overtightening but the machining of steerer tube and stem and shim would need to be soooooo accurate for that to actually work. Try removing the spacer and don't overtighten it!

 

[MacB]

yes it's been updated - that's what I meant.

Never seen a washer in the middle before, and that's clearly what is causing the problem. I guess it's a nice idea to prevent overtightening but the machining of steerer tube and stem and shim would need to be soooooo accurate for that to actually work. Try removing the spacer and don't overtighten it!

Darn, I knew you'd say that, they're steel forks and steerer so they should be ok.....here goes....

 

[Crackle]

I wouldn't remove the washers. How was it packed, could the wrong shim have been packed? If you needed to use it this weekend, I'd be tempted to find something you can expand the shim with until you can sort it or nick a shim from another bike.

Edit: oh I see the washer in the middle now. Never seen that before, I'd take that out.

 

[MacB]

still psyching myself up, my procrastination is nothing, absolutely nothing, to do with the fact that Janes' fresh baking just came out of the oven

 

[MacB]

yep, removing the spacers worked, I measured them and they were 2mm each, as I was tightening the stem I checked to see if the spacers would fit back in. Before I'd even tightened down fully the gap was less than the spacers.

 

[e-rider]

yep, removing the spacers worked, I measured them and they were 2mm each, as I was tightening the stem I checked to see if the spacers would fit back in. Before I'd even tightened down fully the gap was less than the spacers.

jolly good - just make sure you haven't overtightened them - I think it's about 5-7Nm for stem bolts but check this

 

[buddha]

For another 5 quid you could have got something decent, like a Planet-X Superlight stem

 

[MacB]

For another 5 quid you could have got something decent, like a Planet-X Superlight stem

It's a good point, the performance differences on stems are staggering, with the right one I could compete in the TdF. Obviously it would need to have a ngative weight of about 40kg and magically transform my fitness levels, but I'm sure the technology exists.

It's a stem FFS!!!, if it's the right size and doesn't snap then it's good enough

 

[MacB]

jolly good - just make sure you haven't overtightened them - I think it's about 5-7Nm for stem bolts but check this

I don't think the bolts are overtightened, I went past the point where the spacer washers would no longer have fitted with just fingertip pressure.

 

[potsy]

jolly good - just make sure you haven't overtightened them - I think it's about 5-7Nm for stem bolts but check this

Just don't put your full weight behind it Mac and you'll be fine

 

[Crackle]

Just don't put your full weight behind it Mac and you'll be fine

Especially with all that fresh baking inside him.