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Old 10-14-07, 10:14 PM   #1
D3V1N
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shifter limits for applied force?

I am working on a custom set-up that is going to need to use a friction or indexing shifter (most likely bar end). Something I need to know is what sort of tensile force applied to the cable are most shifters able to handle?

Thanks for any help.
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Old 10-15-07, 12:41 PM   #2
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*bump*
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Old 10-15-07, 12:47 PM   #3
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Why? The cables should be able to handle any (normal) pulling force that you would apply. I've seen exploded housing, but never a snapped cable unless they were really old.
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Old 10-15-07, 03:18 PM   #4
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taking data from this site: http://www.sicklines.com/reviews/pow...-shift-cables/

your typical steel cable has
Diameter=1.27mm
Tensile strength=2.8GPa

So 3547N (~800lbf) to fail on the cable side of things. What the hell are you planning to do to your shifters?
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Old 10-16-07, 07:04 AM   #5
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It's not necessarily the cables that I was wondering about. I am more concerned about what sort of forces the friction or indexing shifter are capable of handling. Such as, what force can you apply to the cable before the the shifter will move?

Thanks
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Old 10-16-07, 09:19 AM   #6
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When I had downtube shifters, the friction had to be adjusted really tight (and often) or the bike would shift up or start clacking occasionally when I was out of the saddle. I've never had that problem with STI.
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Old 10-16-07, 10:53 AM   #7
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Originally Posted by D3V1N View Post
It's not necessarily the cables that I was wondering about. I am more concerned about what sort of forces the friction or indexing shifter are capable of handling. Such as, what force can you apply to the cable before the the shifter will move?

Thanks
what are you trying to do with them?
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Old 10-16-07, 11:04 AM   #8
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It's not necessarily the cables that I was wondering about. I am more concerned about what sort of forces the friction or indexing shifter are capable of handling. Such as, what force can you apply to the cable before the the shifter will move?

Thanks
I seriously doubt that you will find a specification for this. Shifters are designed to work with derailleurs and the normal forces they apply to them. Beyond that, you are on your own.

If you are planning to use a bike shifter in some other application than moving a derailleur through a low friction cable setup, then you may need to purchase a shifter and do some pull testing on your own.
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Old 10-16-07, 11:19 AM   #9
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I think it's a good question. I've never pursued exact measures in lbF or N or whatever, but I have been curious about the friction shifter adjustment being optimal (easily shifted but still able to resist the derailer return springs). I've also wished I could significantly tighten the return springs just to see if they felt "crisper" on the release shift and whether it caused problems on the pull shift. --all fun things to think about.
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Old 10-16-07, 03:51 PM   #10
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I think in the case of bar end shifters the hinge is going to fail before the handle/lever or the shifter/handlebar interface. It'd be relatively easy to figure out the force applied on the hinge if you knew how hard you were going to pull the cable - but I don't have any idea what the limit would be. It sort of sounds like you know all this already though
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Old 10-17-07, 11:21 AM   #11
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Looks like my best bet will be to buy a couple and do some testing.

FYI, the reason I asked is that I am working on a project involving a hand powered cycle. Basically, I need a mechanism to disengage the driven element from the clutch and I figured a shifting lever was probably the simplest solution for this.


Thanks for the replies.
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