Shimano Nexus 8 alternative shifters

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Nigel
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Joined: 25 Feb 2007, 6:29pm

Shimano Nexus 8 alternative shifters

Post by Nigel »

I've a plan to convert a 1980's bike to hub gears. Horizontal drop outs already present, etc.. I'd like to run with drop touring bars rather than flat bars.

Question is the gear shifter. One option I've seen with standard Shimano shifters is to put the grip shift on the end of a drop handlebar with a suitable adaptor (picture on Sheldon Brown's site of his Raleigh).

So, I was wondering if anyone knows the cable pull per gear, and whether it can be operated with other shifters. I'm thinking in terms of the Shimergo or Travelmate adaptors for derraileurs; a bit of creative bodging on the ratio of cable pulls and it all works!.
thirdcrank
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Post by thirdcrank »

I can't help with that level of detail, but before this disappears unanswered, I have Nexus Inter 7. Although I have only ever used the twist grip style , I once bought a complete spare wheel from SJSC and it came with Rapidfire (??) controls, which consist of a sort of band-on rocker (press one end for up, other for down.) I imagine they might mount in the middle of drops, although I fancy they are intended for thinnish bars.

I think the amount of cable movement has to be pretty exact or the innards would be chewed up pdq. Travelmate is a brake adaptor so I cannot seei being much use.

DEepending on howmuch bar clutter you are prepared to accept, you can fit one of those foreward projecting brackets which are intended for computers etc. as they are really like a bit of handlebar, you can mount whatever you like on them.

Image

I've just been and taken a (rather poorly focused) pic of my unused band-on control lever. The knobbly black bit on the right is the actual lever. I can't see anything similar in a quick look at MickF's links. Mine has been in the garage nearly 10 years so things move on.
Last edited by thirdcrank on 11 Apr 2007, 9:18am, edited 1 time in total.
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Mick F
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Post by Mick F »

Sorry Nigel, can't help either.

I'm the owner of a Nexus Inter 8 with Tapfire levers, but on traditional sit-up-and-beg handlebars. The gear controls are combined with the RH brake lever unit.
See:
Wiggle Nexus
and Shimano Nexus

I agree with TC that the pull-per-gear has to be exact.
Mick F. Cornwall
TwoWheelsGood
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Joined: 6 Feb 2007, 8:32pm

Post by TwoWheelsGood »

The new Shimano Alfine groupset has the stand-alone SL-S500 8-speed Rapidfire shifter which should be usable with either Alfine or Nexus 8-speed hubs if this particular shifter can be fitted somewhere on the bars.
Nigel
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Joined: 25 Feb 2007, 6:29pm

Post by Nigel »

Thanks for comments so far, and I knew about the Alfine shifter.

The Alfine shifter is for a 22mm bar (standard flat bar size), and a typical drop bar (measuring one in my shed) is more than 23mm. In principle, if there is enough metal, I could take the alloy bar mount from the Alfine shifter and bore it out to 23.x mm (I have access to machines which could do it). I'd also have to deal with the aero routing of brake cables (not expecting a problem, but measuring needs to be done). That might be the option I take.
I've been offering up a similar-ish 7speed shift lever to a drop bar to see how it falls on my fingers.

I'm not that keen on auxillary bars. I'd like this bike to be fairly clean of clutter, and I'm also a habitual bar-bag user.

I still remain more interested in cable pull and whether any option with a Shimano/Campag STI/Ergo lever might be possible. An intermediate pulley to alter the actual cable pull may be needed, but the amount pulled per gear click over the whole range needs to be the same ratio as the amount per click on an STI/Ergo.



- Nigel
thirdcrank
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Joined: 9 Jan 2007, 2:44pm

Post by thirdcrank »

The big difference between a 7 speed lever like my pic., and the Alfine, which would work a Nexus Inter 8, is the construction and attachment of the hanlebar clamp. The seven speed, though for thin bars, is only held on to the body of the lever by an allen screw. It would be easily removed and replaced by something to taste, by anybody with the skills make something else. It looks as though the clamp on the Alfine is of intrinsically better quality and it forms part of the body of the lever assembly.

I am too simple-minded to envisage one of these hubs working with anything other than a purpose-made lever. I expect it would be easier to source a pair of old Raleigh steel bars off a Lenton Sports or similar, which would be thin enough for the tapfire control, but I suspect that might be not what you have in mind.

Presumably the company would provide technical info in reply to an email; they must know the answer or they could not make the controls. Alternatively, you could borrow a control lever and measure its pull. No point using mine - the 7 and 8 may have different lengths.

(I see Hubbers bought a SRAM Spectro on Ebay with some sort of electronically controlled shift. Presumably one of those would do away with all the cable routing and everything.)
RJC
Posts: 188
Joined: 30 Jan 2007, 7:17pm

Post by RJC »

You could try contacting Jay Guthrie who makes the ShiftMate.
http://jtekengineering.com

In email contact with him a couple of years ago he mentioned he was investigating Nexus hubs. At the time he had only measured the cable pull for a 7 speed Nexus about which he said "The total cable pull of the 7sp is 1.225 inches or about .204 per shift". The is very similar to the cable pulled by an SRAM ESP 7 speed shifter from a measurement I made. Of course it doesn't necessarily follow the same will be true of the 8 speed systems.

I was asking Jay about the possibility of a ShiftMate for mixing Shimano & ESP derailleur systems but he said the difference in cable pull was too large. I see he now has ShiftMates for SRAM road derailleur gears and an in-line adapter for mixing 1:1 ESP gears & Campagnolo.

Robin
Nigel
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Joined: 25 Feb 2007, 6:29pm

Post by Nigel »

Thanks Robin,

that proved to be an inspired suggestion. Jay replied within a couple of hours and said they're working on something to go with SRAM shifters, check website in a few weeks time.

Jay said SRAM have uniform cable pull, as do hubs, whereas Ergo and STI have different pull at each end of their range.


- Nigel
RJC
Posts: 188
Joined: 30 Jan 2007, 7:17pm

Post by RJC »

Interesting.
Did he say whether he was working with the road group shifters or MTB ones? I suppose it would be the road shifters since I can't see any reason for wanting to switch to SRAM MTB shifters with hub gears.

Robin
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