Cable pull modification hack for 9S shifter/cassette, 10S clutch derailleur (SRAM GX)

[Pancake]

Summary: added strip of copper to my bar end shifter lever cable guide cut our, now it pulls more cable so it works with a clutch derailleur.

Details: Trying to use the following for a wide gear range like the “Ultimate Turkey Vulture”:
Microshift 9-speed/friction bar end shifter
SRAM GX 10-speed derailleur with clutch
9 speed cassette (Sunrace 11-40t)

The problem with this setup is that the 9S shifter doesn’t pull enough cable on this 10S derailleur for it to reach the full range of the 9S cassette. Crust has a solution in a cable pull modifier kit (JTec and another company make them too). But then I remembered a post here or on the Blagh showing a piece of housing over a downtube shifter lever where the cable curves around it, that created additional cable pull - figured to try something similar but hosing can’t fit at the lever‘s curve just past where the cable head sits. But something could fit under it.

Cut some copper sheet from a pipe hanger (approximately 15mm long, 2.5mm wide, 1mm thick). Pushed it into the cable guide cut out in the shifter lever.

Not sure if this is a good idea or if will need to be reversed but a little super glue holding the copper strip for now could be removed later or some JB weld added if needs to be made more permanent.

Shifts the full range of the cassette easily now - unmodified I could get it to shift into every gear but it was just not quite a solid connection in the 11t or 40t gears. Now it shifts smoothly (only trying friction here) and the clutch makes for nice engagement.

I wanted to use a clutch because I’ve had some chain drops, the chain can feel noisy when everything else is quiet, and a few too many times the chain decided to smack the frame for bouncing over rocks and things. I’ll ride it hard on Sunday and report back.

Tell me if this is a terrible idea please, I’d rather find out at home,
Abe

[Pancake]

Late night post corrections:
1. Turkey Vulture Supreme, not Ultimate.
2. Probably zinc, not copper.
3. Tanpan is the other cable pull modifier maker.

Very much looking form suggestions to improve this. Different material? JB welding in place enough to make reliable?

The rest of the bike setup:
Sam Hillborne 56cm
Dirt drop bars
VO double crankset 46/30t
Microshift friction front derailleur
CX70 front derailleur
9-speed chain that’s now a few links too short because of the longer derailleur cage (had XT 9 speed RD before).

[Pancake]

More corrections: measured with calipers and my estimates were not great for the size of the added metal piece:

25mm long. Could probably be 20mm long and work equally well.
1.8mm wide
0.8mm thick

[Bill Lindsay]

Good work.  APPROVE.  

In 2020, 3D printing is totally dialed.  Somebody with the time and the CAD station could build a 3D model of an accessory piece that would snap onto a Silver shifter, increasing the cable pull.  Post that model on Shapeways.com and anybody in the world could click and order it in plastic or metal.  Plastic would be fine.  The price of these things are purely based on the volume of material because that represents how long the printer is running.  Such a piece would only cost a couple bucks to print.  Charge $15 for it and make a decent margin.  That would be cool!  I'd buy one.  

Bill Lindsay

El Cerrito, CA

[Pancake]

Took a quick spin tonight: it works a dream, could be a tiny fraction thicker but as is it leaves a meaningful amount of extra lever movement range before it’s stopped by the limit screws at the derailer. It could move the derailer another 5mm plus for top or bottom gear (enough to shift off the bottom or over the top gear if not stopped by the limit screws).

Thanks Bill. I’ll send you one myself (shout me where you’d like it sent by email).

I’m going to fix up another that’s a nicer finish and very tight fit so the glue or epoxy will almost unnecessary.

Abe

[ascpgh]

This is the sort of hack I envisioned for my NOS Mavic/Simplex DT shift levers pertinent for 9-Spd before I accepted that they were going to be just way too dang far down there on a 64cm frame to worry about if or how well they worked. If the functional capstan diameter around which the cable wraps as the lever is rotated was increased.by some amount, the wonderful shifting feel could carry on into the 9-Speed world. 

I thought about a tube of a particular wall thickness to put the cable through that had a widened end to stop in the lever's recess for the cable end bead. The hole drilled through the lever for the cable enlarged enough to accept both  the thickness of the cable and added sleeve. The bead recess enlarged, if needed, to continue acting as the stop for both the cable and the sleeve. Flexibility would help insert through the lever passage, being more rigid and shaped would cause less cable tension to make it take shape as would be operated and cause less "noise" to the shifting function as tension is taken and given during shifts. 

Andy Cheatham

Pittsburgh

[Pancake]

40 miles today across Napa to Lake Hennessy and back with the new setup: great! Significantly quieter and shifts great, better than the XT RD before.

Abe

[Matthew P]

I like this stuff and I'm looking to set up something along these lines.

I was having a hard time grasping it but I think I have it: 

The bar end shifter is basically a circle (/spool/reel) wrapping & releasing cable.

The metal insert increases the radius/diameter/circumference of that circle.

Now the same travel of the lever - or same change in angle - results in a larger distance moving on the outside of that circle - and more cable pull.

Common analogy: in one rotation of a spinning record, a point on the edge of the circle label in the middle travels less linear distance than does a point on the outer edge of the record.

But they both travel the same number of degrees: 360.

Insert angular velocity stuff here.

So this is different than the Shimano 600 bar end shifter and the hacked versions that get more cable pull by having greater movement of the lever - 180 degree swing or whatever it is.

I wonder:

What I can do for thumb shifters.  Hack my microshift thumb shifters or do the lever+(Paul or VO or..?) "Thumby" allow for more options?  Maybe I hold onto my Paul's..

So the 9 speed chain is fine with the 10 speed derailer?

Would a 10 speed chain be better?  I hear reports of 10 spd chain on 9 spd casette is good.

Definitely go with the Sram clutch (rear) derailer instead of a Shimano?

Thats all I can recall.

Thank you much for sharing.

-Matthew 

San Diego

[Pancake]

Matthew, you got the mechanism right (larger diameter circle in the lever section where the cable is guided through causes more cable to be pulled). 

Re: Shimano 600 bar ends - I didn't know about that one but that was my first thought when fiddling with the shifter - can't I grind something away to allow more movement of the lever? A quick look told me this would be complicated and I did not actually want the bar end lever to stick that much further up (when pulling to easier gears) or further down and forward (when in harder gears). 

Next, I thought of the folks who mix Shimano & Campy components by adjusting the cable routing at the rear derailleur but the mechanics of it didn't quite make sense to me to get enough additional pull. For example, here among many others.

But my kludge seemed the simplest version so long as you have abandoned hope for matching any indexing - friction for the win here. I may try the indexing of my rear shifter (it can work in friction or index mode) just to see if I randomly got it close to the right change of diameter at the lever, but I'm nearly certain that's just for fun and it won't index anymore. 

I just ordered quite a few jewelry brass bars that are 20*2*1mm, 22.5*2*1mm, and 25*2*1mm for a few bucks and I'll bend them into arches to see if they fit nicely (I suspect I'll need to grind down the width a fraction of a millimeter). If they fit nicely I'd be happy to mail you a few to experiment with. 

I believe this would work equally well for Shimano bar ends, Microshift friction thumb levers, and others ... basically anything where you can see the cable guide in the lever and add something that will lay under the cable as you pull the lever.

While I really like the SRAM GX shifter and Crust gives it a good endorsement in their Turkey Vulture Supreme article, there are quite a few poor reviews out there. The B-screw apparently is weak and bends if pushed much, the derailer itself is a bit loose feeling compared with Shimano (my only other experience) which is another complaint others mention. But for me it's working very nicely - the clutch's impact is exactly what I hoped for compared with the Shimano XT 772 Shadow it replaced: 

+ Significantly quieter while riding.

+ No chain slap on big bumps.

+ Strong / more confident shifts - before it would make some noise after a shift and I'd fiddle with the level until it quieted down, but with the GX it's quiet right away.

- It is glossy black while I'd prefer completely silver/polished, but, meh, don't really care. 

The 9-speed chain is happy with this setup, I may try a 10-speed chain just to see if that's improves anything (my memory is that the Crust article said 9spd was fine). I do need to add a couple of links to the chain because the long change and routing of the GX take a bit more than the XT.

Abe

[Bill Lindsay]

thank you for offering to send me one.  That's not necessary.  If I need something like it I'll want to do my own work anyway...  Offer it up here for the less fabricationally inclined.  

Bill

[Matthew P]

Abe,

I'd gladly send you some bucks for material, shipping etc to try it out.

I'm trying to get hot on this stuff with one bike to sell and one bike to build.

And I've been on the fence about which shifters to lose on the bike for sale and what to keep.

This/these could influence my decision.

Please send me a private message with your paypal etc. if you are inclined.

Here is some copy and paste (can use to find the actual thread) where I got that Shimano 600 lever bit of info:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Peter Trasko

6/8/17

Resurrecting an old thread, but I made a chance discovery that may be of interest to the group.

One limitation of friction-shifted 10 and 11 speed bikes has been the throw length of bar-end shifters. Some people have gotten around this problem with judicious filing of the bar-end pods, like Ultraromance did here with this amazing ride.

I'm here to tell you that this filing isn't necessary.

I mounted late-model Shimano 600 downtube shifters (these ones) on generic Shimano bar-end pods. These shifters, on these pods, will pull through a full 180 degrees. On a 10 speed cassette they move a little over 90 degrees. I haven't tried 11 (or 12), but I guarantee that it will work. How do I know? With the chain removed and the derailler limits backed all the way out, the shifter will easily pull the derailler into the wheel and beyond. These shifters are also truly "light action", in that you can easily move them by tiny increments. With 10 speed you just never miss a shift.

Hope this helps! I'm friction shifting a mega-wide-range system of various parts and just loving it. In the rear I have a 10-speed 11-42 cassette. In the front I use a SunXCD 26-46 double. Altogether I can pull my kid trailer up alpine passes (I live in Switzerland) and my top speed is about 40km/hr - which I can only reach on steep descents. I have the range I need!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`

Good stuff.

-Matthew

[Pancake]

Matthew (and up to 5 or 6 others I suppose), if possible please email / private message me where to ship it to. 

Made up an extra tonight after replacing my original metal bit. Slightly thicker brass, it’s 2mm wide by 1mm thick but by bending it to a round shape it bulges just enough to be a VERY tight fit. So I ground a thin layer off one side and it fits a charm. Super glue is probably unnecessary but I used a bit anyhow. Removal after the original pieces was glued there probably made fitting this version a bit harder, but not bad. I’ll ship to anyone willing to try it and report their results. 

If I could start over or for a future build, I want to have a set of friction 2x9 drivetrain; 46/30 GRX double, 11-42t sunrace cassette, Sora 8-speed model double front derailer, and this SRAM GX 10-speed rear derailer. Could just as well make it a 1x11-46t setup.

I was eyeballing the Silver 2 shifter for similar treatment on my Cheviot, but that’s a project for another day (or for a Platypus!).

Abe

[Pancake]

Now with the photos I forgot to attach. Brass jewelry “bars” at 25x2x1mm (long x wide x depth) for maybe $0.35 each plus ten minutes bending and whatnot. 

Fits in a Sunrace lever too (same 2mm width) so can replicate with thumb shifter levers:

Version 1.0 while installed, messy, barely enough additional diameter at 0.87mm thick:

The removed and destroyed v1.0 vs new v2.0:

  

The parts:

Open to ideas on how to get an easier and more consistent curve (currently using round nose jewelers pliers which are just okay. 

Abe