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Shifter cable pull

Old 05-16-04, 11:48 AM
  #1  
Jonny B
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I'm considering putting a Nexus internal geared hub on my next bike, but (according to Shimano's website) they only come with flat bar grip shift or lever pod things (not sure what the technical term is). I want either a thumbshifter or a barcon (bike will have either bullhorns or drops), but I can't just use the friction setting because hub gears need perfect indexing. Does anyone know how much cable Nexus shifters pull, or any other type of shifter, or what shifters would be compatible with Nexus hubs? If it matters any, I'm gonna get the 8 speed hub.

Last edited by Jonny B; 05-16-04 at 11:55 AM.
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Old 05-26-04, 12:26 AM
  #2  
yoni
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Bump!

I've been wondering the same thing lately.. If you search for "cable pull" in google groups, you can find some of the specs for shimano/suntour/campy index shifters. That is, you'll find out how much road/mtn shifters pull. The question is whether it's the right amount for the nexus hub.

If you're not on an real tight budget though, I don't think the hub/shifter set costs much more than the shifter alone. So you could get the set and then measure the cable pull.

If it's not a close match to the pull-per-click of existing index shifters, but the total cable pull is close, you could probably take apart a shifter and replace the detent plate with a custom-machined one. It'd be a ridiculous amount of work but would make for a good story once the bike's running..

right. I've babbled long enough.. If you find the specs for the Nexus 8 shifter, post them here or in rec.bicycles.tech or PM me with 'em.. good luck.

Y.
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Old 12-29-08, 01:48 PM
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tatfiend 
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Thought I would revive this thread as I have some information that might be useful to others.

Bob Powers on the Yahoo Geared Hub Bikes group came up with the following Nexus8 cable travel measurements.

"Okay, here it is. My twist-shift version of the Nexus shifter uses 39mm of cable for seven shifts. The shifts are exactly equally spaced, meaning that the cable pull is:

5.6mm per shift"

He also found this info for cable travel for a Shimano 9 speed indexed rear derailleur.

"In contrast, here is what a 9-speed Shimano produces, for the 1-2 shift, then the 2-3 shift, etc.:

4.2mm
2.4
1.9
2.6
2.4
2.7
3.0
4.0mm

Data came from an enginerd with good equipment, at:"

http://blogs.phred.org/blogs/alex_we...able-pull.aspx

Some group members have questioned the derailleur cable pull data as being too non linear and pointed out that the first and last shifts are going to be influenced by derailleur travel stop settings. Anyone have anything better?

The purpose of this is to see if any drop bar shifter such as an indexed down tube shifter can be adapted for shifting a Nexus8 or Alfine gear hub.

If any members are interested in geared hub bikes and hubs here is a link to the Yahoo group. The group owner is trying to make it a primary source for gear hub information and links.

http://groups.yahoo.com/group/Geared_hub_bikes/

BTW per the manual Rohloff gear hub cable travel is 7.4mm per shift or about 96.2mm total cable travel for the full shift range.
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Old 12-29-08, 03:05 PM
  #4  
DannoXYZ 
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Thanks for the info! So basically the final result is you can't use any bar-con or DT shifter with Nexus8. Only the Nexus8 lever will work.
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Old 12-29-08, 04:52 PM
  #5  
jtarver
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My research seems to point to the need for a Problem Solver device used for cable pull issues in brake applications. I have all the parts together to do an Iter-7 hub with a triple crank. The list is:
Hub
Chain Tensioner or RD
Problem Solver
I got the Problem Solver and an Alfine chain tensioner from harriscyclery.com for around $50.
sheldonbrown.com and harriscyclery.com have loads of information on Nexus hubs, just not this use of them.
Someone on this board has done this hack, I just can't find the thread, they reported good results.
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