Bars keep coming loose

[GrubNut]

Help this poor sod out. Last 3 races i've had 4 mechanicals. In the last 2 I got DNFs because my bars came loose.

This is a weird one. 30 years of cycling and I've never had handlebars come loose. Now twice in a week. Tonight i had torqued the bejeebus out of it, test rode it for three hours on the weekend, but it still came loose. Carbon flat bars on an alloy stem. Both well used but never had a problem before. Problems started when inverted the stem.

Any ideas before the stem and bars go in the bin?

It's on my singlespeed bike so the bars are getting a workout. Should I be going for alloy bars?

[Grover]

you say both well used - but not specifically if that was together. i assume it was as you mention the problem only started when the stem was inverted but if that's not the case, the stem isn't actually a 26.0 clamp aka road is it?

next, get some good quality calipers and check both the bar and the stem to make sure they are actually the measurement they should be - 25.4mm for mtb standard or 31.8 for oversize. if you've torqued the 'bejeebus' out of it the carbon bar has probably been damaged and won't have a hope of being clamped tight. turf it, get a new bar and get it installed using a torque wrench.

if you want to try again with your current bars, get some dynamic paste (available branded under a few names - tacx, syntace, ritchey are a few) and get it installed with a torque wrench but i wouldn't be using that bar again.

ps. kcnc make a scandium flat bar that is only 120grams at 600mm wide. having great success with mine, just don't install barends, the ends are paper thin.

[k3n!f]

Scuze the obviousness, but did you grease the bolts or try loctite or anything?

[GrubNut]

Thx grover, yes they have been both used together for a quite few months. I am sure that they are both 25.4 clamp.

The bar has probably had it and is now turfed. The extra torquing (over what I would normally torque a carbon bar) was in response to the slipping last week.

The paste is an interesting suggestion - wasn't aware of it , as are the scandium bars. Just found an easton ea50 bar in my parts collection for the meantime.

[craign]

Theres stuff you can get for "lubricating" carbon seatposts/bars. I say "lubricating" because I think it provides extra friction rather than less. Dirtworks sell stuff branded "Ritchey" in little packets. Maybe something like that is the solution?

edit: should have read the thread this has already been suggested.

[jasco]

Thx grover, yes they have been both used together for a quite few months. I am sure that they are both 25.4 clamp.

The bar has probably had it and is now turfed. The extra torquing (over what I would normally torque a carbon bar) was in response to the slipping last week.

The paste is an interesting suggestion - wasn't aware of it , as are the scandium bars. Just found an easton ea50 bar in my parts collection for the meantime.

Chiming in a little late here, but did you keep the faceplate the same way up relative to the stem? (ie if the text on the faceplate was the right way up before inverting, it should now be upside down) There could have been a slight manufacturing tollerence problem? :confused:

-Garth

[GrubNut]

Scuze the obviousness, but did you grease the bolts or try loctite or anything?

Yes mate, ta.

[GrubNut]

Chiming in a little late here, but did you keep the faceplate the same way up relative to the stem? (ie if the text on the faceplate was the right way up before inverting, it should now be upside down) There could have been a slight manufacturing tollerence problem? :confused:

-Garth

Yes, in fact the face plate is upsidedown relative to the stem. You could be onto something there. It might not even be tolerances, it might just be design.

[triples]

Help this poor sod out. Last 3 races i've had 4 mechanicals. In the last 2 I got DNFs because my bars came loose.

This is a weird one. 30 years of cycling and I've never had handlebars come loose. Now twice in a week. Tonight i had torqued the bejeebus out of it, test rode it for three hours on the weekend, but it still came loose. Carbon flat bars on an alloy stem. Both well used but never had a problem before. Problems started when inverted the stem.

Any ideas before the stem and bars go in the bin?

It's on my singlespeed bike so the bars are getting a workout. Should I be going for alloy bars?


tsk tsk tsk

get an oversize bar and stem. more contact so less chance of anything going wrong. Im running a set of OS on my ss and never had a problem. infact Ive never had a problem with any alloy bar/stem combo coming loose

[DarrenHunt]

sorry if its abit late... how are the threads in the bolts?
sometimes threads in bolts can just wear out from alot of pressure... i.e. single speed mtb.

[13677meelo]

Get of u peices of aluminuim and do dh!!!!!!!!!!!!!!

[tu plang]

Get of u peices of aluminuim and do dh!!!!!!!!!!!!!!

:rolleyes: you've got a lot to learn kiddo.

[rangie]

Overtightening carbon is not good from a structural pt. of view even though the mount pts are reinforced a lot (generally).

You could use some 'grease' like the ritchey which comes in smll satchets (about $10 so pricey). This permits you to use less torque. I've used this on my seatposts as well with great success. A couple of bikes and more left for another day. Considering the cost of a frame (for seatpost), the $10 is a steal :-)

Ensure the surfaces are clean, the threads on the bolts are clean, and you might also use some loctite on the threads to sto pthem working loose.

HTH