thinktubes 

I'm installing some clamp-on DT shifters, but I'm worried about crunching the tubing. Couldn't find a torque value anywhere.

abshipp 

Tighten until the tubing buckles, then back a 1/4 turn. Should be the proper torque value.



In all seriousness, I wouldn't worry about it. Round tubes are incredibly strong in compression radially. Assuming you are using shifters with a steel band clamp and small screw/nut combo to secure them, I highly doubt you would be able to generate enough force to damage the tubing.

If you're still concerned, I would install them lightly, and progressively tighten them to the point that the shifters don't move around when you're operating them.

SurferRosa

Use a 5/16" socket driver and you don't have to worry about torquing it too much. Do the same with all your anchor bolts.

r0ckh0und 

I would think that the band would break or deform before the tubing

Salamandrine 

A more important question is whether or not there is a brazed on stop for it. If not, those things do tend to slip.

Nobody torque spec'd stuff like that BITD. I'd say typically it'd be around 5-7 ft/lb, about like a front derailleur, maybe a bit more.

thinktubes 

Thanks for the replies. Found some info on Park tools site. https://www.parktool.com/assets/img/...elp/torque.pdf

they suggest 44-60 in/lb for Shimano clamp-on front derailleurs, which should be close

rootboy 

They do. And on a couple of mine I coated the back side of the clamp with clear PlastiDip.
To give a little cushioning "bite", and to help protect the paint.

smontanaro 

I suspect the only exception would be the Huret Jubilee front derailleur, whose clamp was extremely thin and fragile. In that situation, I think you'd iterate. Tighten just enough to hold in place, cable it up, see if it spins under load. If so, tighten it a bit more. Lather, rinse repeat until it holds while shifting.

niliraga 

thanks - this is a genius notion, so much more appealing than my ugly slivers of inner tube.

rootboy 

One caution. Put on thin coat, and let it dry VERY thoroughly before mounting.
I usually let it sit for at least two days. Takes a long time for that stuff to thoroughly set.

non-fixie 

mpetry912 

Are you familiar with the concept of "running torque" ? Just clean the pinch bolt, put a dab of grease on it, and tighten until the running torque starts to increase in a non linear manner. Go just a tiny bit more - like 1/4 turn - and you're done.

BITD there were no torque specs on stuff like this. Learn to develop a feel for how tight is tight enough.

Mark Petry
Bainbridge Island, WA USA

thinktubes 

In a previous life, I worked in as an EE in aerospace. Many projects had the electronics housed in machined aluminum enclosures.

While learning the concept of "running torque" I snapped the head off a screw.

This earned me a trip to the machining building where I had to ask "Green Head Ted" and "Five Eye Bob" to remove it for me. I was 23 and Ted and Bob were 5000 years old.

This experience cured me from using the "calibrated wrist".

mpetry912 

well, it cured you ! kind of like BMW head bolts which are torqued by degree - tighten to xx torque and then 90 degrees from there.

many failed, resulting in blown head gaskets.

I do think the running torque technique applies for clamp band shifters, since you are tensioning the band around the tube - before the bolt is put into tension. Very difficult to come up with a torque recommendation in this application.

I don't think I've ever stripped a bolt ! I have developed a good feel for when a fastener is pulling up and for how much is enough.

Mark Petry
Bainbridge Island, WA USA

Uyle

I use clear tape then cut around with razor blade.