Broken Twistshifter Bracket

[High Moors Drifter]

Just started out on a ride this afternoon and noticed the whole twistshifter was moving on the handle bars when changing gear. I stopped expecting to just tighten the screws holding the shifter in place but instead found the bracket had sheared in two. Considering my mileage on the bike is not that high and it’s only ridden on metalled roads I’m quite surprised. Anyone else had this problem? I’m hoping I don’t have to replace the whole shifter which will be an expensive exercise.

Id.

[geocycle]

Oh no! Never heard of that happening. Which shifter have you got?

[Andre Jute]

Never heard of such a thing before.

It is possible you simply got a rogue piece of metal.

However, the most likely cause is over-tightening, possibly repeated over-tightening.

See about a torque wrench, which measures tension on fasteners, at http://thorncyclesforum.co.uk/index.php?topic=13067.0

[Prince of Darkness]

I had the same thing happen. Put it down to over tightening as well. Those brackets are very lightly made and I think care needs to be taken not to over tighten. Still don't have a torque wrench, but I took more care with the new one
The bracket can be bought as a separate item, not too expensive.

[High Moors Drifter]

Thanks for the responses.

The shifter is the wave design it’s fitted to a Mercury purchased from SJS in June 2015. I’ve not moved or adjusted the shifter hence it’s not been tightened since originally fitted. After this time it’s unlikely to be covered by any guarantee and I’m hoping I don’t have to purchase a complete shifter at £69.99.

I’ve as yet to contact SJS to see if it’s possible to just purchase the pulley enclosure.


Id

[Prince of Darkness]

Costs £15.99 from SJSC

[Dave Whittle Thorn Workshop]

You probably just need https://www.sjscycles.co.uk/hub-spares/rohloff-tx20-screws-clamp-for-twistshifter-light-8193/

Its intentionally weak (like a fuse) so that it shears before damaging the handlebar, it was introduced as part of the twist-shifter light concept with the advent of carbon and thin walled alloy bars.

[High Moors Drifter]

You probably just need https://www.sjscycles.co.uk/hub-spares/rohloff-tx20-screws-clamp-for-twistshifter-light-8193/

Its intentionally weak (like a fuse) so that it shears before damaging the handlebar, it was introduced as part of the twist-shifter light concept with the advent of carbon and thin walled alloy bars.

Dave.

Thanks for that, order just placed. Still a bit concerned how or what caused the failure. Quite often I ride with my hand on the twistgrip, the roads here can be very rough with broken surfaces, cattle grids and speed humps such that I’ve lost three rear lights that have shaken loose from my saddle tool bag when riding at speed, could this place extra stress on the clamp?

Regards Id.

[Prince of Darkness]

I think it is just like Dave said, it is deliberately engineered to be weak in order to prevent the risk of causing damage to lightweight carbon fibre or thin walled aluminium handlebars. Better a broken bracket than a catastrophic failure of the bar! If, like me, you fitted the shifter without using a torque wrench, it would be very easy to over tension the bracket. Of course, if you did use a torque wrench set to the appropriate force, then that does not apply

[High Moors Drifter]

I think it is just like Dave said, it is deliberately engineered to be weak in order to prevent the risk of causing damage to lightweight carbon fibre or thin walled aluminium handlebars. Better a broken bracket than a catastrophic failure of the bar! If, like me, you fitted the shifter without using a torque wrench, it would be very easy to over tension the bracket. Of course, if you did use a torque wrench set to the appropriate force, then that does not apply

The shifter was fitted by SJS and hasn’t been touched by me since purchasing the bike. I’m sure they fitted this correctly, I’m just keen to find out if my use of the bike contributed to the failure.


Id

[Danneaux]

...I’m just keen to find out if my use of the bike contributed to the failure.

Maybe the consequence of time and vibration?

Best,

Dan.

[Dave Whittle Thorn Workshop]

Dave.

Thanks for that, order just placed. Still a bit concerned how or what caused the failure. Quite often I ride with my hand on the twistgrip, the roads here can be very rough with broken surfaces, cattle grids and speed humps such that I’ve lost three rear lights that have shaken loose from my saddle tool bag when riding at speed, could this place extra stress on the clamp?

Regards Id.

Probably the case, we generally suggest avoiding riding full time on the shifter, its not the most ergonomic shape and can lead to nerve problems.