SRAM Locking Up

[martint235]

Ok this has happened 3 times now so is obviously an issue. I've got SRAM Red on Lelly and sometimes if I hit a pothole, the whole front wheel locks up. Now it doesn't really matter what you do at this stage, you can stand and do nothing (worked on Friday night) or you can try to move the calipers (they won't) or pull the brake lever (it won't move). Give it a minute though and it will suddenly release everything and you can carry on your way, the only issue will be that the rear indexing has been nudged out of line slightly.

Any ideas? Any suggestions other than not hitting potholes?

Cheers

 

[VamP]

It's not clear from your description what is jamming? Brake callipers on rim? The hub? The shifters?

 

[martint235]

Calipers against the rim but also the brake lever won't push inwards and it's at the normal "resting" point rather than pulled against the bar. The gear change lever still moves freely however. Hub seems fine as you can force the wheel to turn just about.

 

[fossyant]

Sounds very odd - have you checked the cables are running smoothly - disconnect the cable and check operation of brake lever and the brake calliper !

 

[Scoosh]

Calipers against the rim but also the brake lever won't push inwards and it's at the normal "resting" point rather than pulled against the bar. The gear change lever still moves freely however. Hub seems fine as you can force the wheel to turn just about.

This part I don't understand.

SRAM Red/Rival etc brake levers only operate brakes - they don't push 'inwards' (towards the centreline of the bike) - unless by 'inwards' you mean towards the handlebars ...

The gear change paddle is the 'double-tap' gear changer.

Apologies if I am 'granny/eggs'

In any case, this does not really solve your problem.
I'd go with Fossy to start with.

 

[martint235]

That's the thing. Once it's had its couple of minutes hissy fit, it all runs fine again. Brakes are ok etc.Cables and caliper seem smooth in normal operation.

Yes I do mean that the levers won't pull towards the bars although the gear lever is still independent.

It's got me stumped.

 

[2Loose]

As already said, check the cables, particularly that the nipple is properly engaged in the lever.

 

[martint235]

Everything cable-wise seems ok. I'll check the cables again next time while it's locked. It's the time-release kind of thing that's weird. Leave it a minute and it's suddenly ok apart from the gears being knocked out half a barrel adjuster turn or so.

 

[RecordAceFromNew]

Mmmm not only is this weird, it could be a bit worrying I think.

These might not be the only ways for such phenomena to arise, but it seems to me they likely result from a) front brake cable or outer pulled and kept pulled until relaxing gradually on its own, and more intriguingly b) rear gear cable or outer is pulled while the mech is restrained from shifting further, by e.g. the L limit screw, or by the chain running out of freedom to traverse sideway. You see otherwise I think neither pulling or pushing the gear cable or gear outer can mess up indexing. Something has to be deformed by stress in the gear cabling system - perhaps the gear outer isn't fitting snugly into the end ferrules, or perhaps the outer gets squished (which it is specifically designed to be able to resist) by a VERY substantial force... It can't be good for the shifter.

The question then is what could be the fundamental cause.

For potential handlebar issues you could concentrate on the right hand side (front brake, rear mech). Are you sure the cabling or handlebar itself is "intact" under the wrap?

To me the reason why it is potentially worrying is while perhaps very unlikely it could be due to flexing of part of the handlebar/frame between cable stops, resulting in forceful pulling of cable when the pothole is hit. Therefore if I were you I would check everything including the frame carefully until finding the culprit. I don't wish to scaremonger, but better safe than sorry!

 

[MacB]

To me the reason why it is potentially worrying is while perhaps very unlikely it could be due to flexing of part of the handlebar/frame between cable stops, resulting in forceful pulling of cable when the pothole is hit. Therefore if I were you I would check everything including the frame carefully until finding the culprit. I don't wish to scaremonger, but better safe than sorry!

He's a powerful guy and I did get a mental image of broken bars but surely that would be far more evident? The point about it being one side orientated is a good one though.

I'd say start with the brake, at the caliper, and work back, there are a limited number of options. First establish that it's the caliper moving to the wheel and not movement by the wheel itself...though an earlier post indicates the hub's been checked for play etc and I'm not sure how that could cause total binding anyway.

If the wheel is ok and the caliper itself is functioning normally then it must be cable related. Something skewy with the cable inners or outers, or something else acting on them. As it's happening on hitting a pothole then it takes a fair bit of force to make it happen.

 

[RecordAceFromNew]

He's a powerful guy and I did get a mental image of broken bars but surely that would be far more evident? The point about it being one side orientated is a good one though.

There is a possibility, that the right side of the handlebar is partly held together by the cable/outer (and of course the tape! ).

 

[MacB]

There is a possibility, that the right side of the handlebar is partly held together by the cable/outer (and of course the tape! ).

Scary isn't it....could it be within the stem clamp area?

 

[potsy]

Is this the same bike you were having trouble with the rear mech the other day?

I really hope this turns out to be sommat stupid, ham fisted fettling by the sounds of it

 

[RecordAceFromNew]

Scary isn't it....could it be within the stem clamp area?

Probably not, since brakes and gears aren't affected by loosening the stem. I think the issue is underneath the wrapping on the right hand side of the handlebars. It could be e.g. that the wrapping is loose, allowing both outers underneath to be pulled/twisted away from the cable stops at the brifter (which will have the same effect as pulling both cables).

 

[martint235]

It is the same bike I was having problems with the other day cos it had done this locking up thing and I was fettling the brakes.

Anyway I think I may have found the problem, or at least I've found something that isn't right that may be causing the problem. I noticed this morning that the right hand lever was turned more outwards ie not in line with the bike so I moved it back. This didn't take any force at all so it seem the lever is loose on the bar. Now I haven't taken the tape off yet, do I need to do this to tighten it up? I can't see or feel anything under the tape to tighten it. Any ideas? These are 2011 SRAM Reds.

Thanks for all the help so far!