Gravel bike derailleur problems

[booglebug]

Installed an XTR crankset on an otherwise 6800 groupset hoping for lower gearing on these rocky climbs I ride after finding my 50 tooth chainring was hardly being used. Having problems with not enough cable pull for front derailleur. Installed a 10 speed derailleur that helped the problems some but still not enough cable pull, would a 9 speed help or will a mountain bike derailleur solve the problem? 135mm rear axle, 48.8 crankset chainline.

[dem]

I'm using an XTR crankset (44/30) on my CX/road frame, and a road FD (Ultegra 11 speed)

All the bottom bracket spacers had to go on the non-driveside for it to shift properly (I did end up machining down some of the crankarm bolt engagement teeth so I could eliminate one, and then I moved my cleats on one shoe a couple of mm to attempt to balance it out)

Hope that helps.

[booglebug]

I'm using an XTR crankset (44/30) on my CX/road frame, and a road FD (Ultegra 11 speed)

All the bottom bracket spacers had to go on the non-driveside for it to shift properly (I did end up machining down some of the crankarm bolt engagement teeth so I could eliminate one, and then I moved my cleats on one shoe a couple of mm to attempt to balance it out)

Hope that helps.

I ended up putting 2 spacers non-drive and 1 spacer drive-side. Been thinking about some machining also but hoping to solve the problem before I attempt it.

[dem]

I took about 1 mm off the teeth in the crank arm so it would sit deeper on the splines. That left me with 0 spacers on the drive side and 2 on the NDS.

Workin' fine for 2000ish miles so far.

[booglebug]

I took about 1 mm off the teeth in the crank arm so it would sit deeper on the splines. That left me with 0 spacers on the drive side and 2 on the NDS.

Workin' fine for 2000ish miles so far.

Did you have to shorten the spindle end?

[dem]

Nope - I figured it was easier to machine the the crank arm (I just stuck it on another crank backwards as a guide, and took a dremmel mill bit and zipped around.) I doubt 1 mm will weaken that interface much, especially when I looked at an XT arm that has even less engagement teeth depth.

If you want to get rid of more than 1 spacer, you'd probably have to mill the spindle and roll more teeth into it, which is way beyond my tools/skills.

Of course all this could be solved if road crank manufactures would start shipping sub-compacts in volume, but nothing much yet!

[Lovetoclimb]

Another option is take an Ultegra CX crank (46/36), swap the 36 for a 34, and set up your rear derailleur with an XT long cage and the Tanpan shift mate. I have a low gear combo of 34x40 with the possibility of going to 42 or maybe 46 in the rear, though that may push the limits of compatibility...

But this is all being used with no issues on my Soma which weighs somewhere around 10 stone or so it seems during the long days of mountainous riding.

[booglebug]

Thank for the ideas Dem ! If no one comes up with a derailleur that will work I'll start machining. Kind of handy at that since it's my trade.

[commonguy001]

I'd contact jtek and see if they have a shiftmate that will do the trick. They say you can use the #7 with a road triple and MTB triple front so maybe that would work?
I may be worth looking into

[booglebug]

Another option is take an Ultegra CX crank (46/36), swap the 36 for a 34, and set up your rear derailleur with an XT long cage and the Tanpan shift mate. I have a low gear combo of 34x40 with the possibility of going to 42 or maybe 46 in the rear, though that may push the limits of compatibility...

But this is all being used with no issues on my Soma which weighs somewhere around 10 stone or so it seems during the long days of mountainous riding.

The 42-30 works great for the terrain in my parts, hoping to make it work.

[Ken Robb]

The 42-30 works great for the terrain in my parts, hoping to make it work.
9 speed Shimano and other triple cranks were 52-42-30 so How about using just the middle and small ring from one of those?

[booglebug]

9 speed Shimano and other triple cranks were 52-42-30 so How about using just the middle and small ring from one of those?
Have already mounted the XTR and hoping to make it work. Thanks for the ideas, keep them coming.

[Ken Robb]

Your BB may be too big {73) to use with road cranks and BB of 68mm. anyway.

[ColonelJLloyd]

Have already mounted the XTR and hoping to make it work. Thanks for the ideas, keep them coming.

I've read this thread a couple times and I am missing the part where it's established an XTR FD is not an option.

FWIW, my gravel bike has a MTB double crank with the corresponding FD shifted with road shifters (all SRAM) and it is about the best front shifting I have experienced. My frame has a 68mm shell and I use one 2.5mm spacer per side as directed. And Q isn't bad at 156mm.

[RudAwkning]

I've read this thread a couple times and I am missing the part where it's established an XTR FD is not an option.

FWIW, my gravel bike has a MTB double crank with the corresponding FD shifted with road shifters (all SRAM) and it is about the best front shifting I have experienced. My frame has a 68mm shell and I use one 2.5mm spacer per side as directed. And Q isn't bad at 156mm.

Don't think a 6800 shifter will have the proper cable travel for an XTR front mech.

[HillDancer]

I'm using a Shimano FD-M986 with an XTR M985 crankset, and SRAM grip shift. The FD-M986 is designed for a max 44T ring and 14T max spread, and 48.8 chainline. Shift performance was poor with a 44T ring, it's much better with a 42T. Reliable shifting required a lot of adjusting to get right. While SRAM pull is fine with an older Shimano road FD, it's less than optimal pulling their MTB FD. There will probably be a similar mismatch with Shimano road shifters, but I think you'll be able to make it work.

Another issue I encountered with that chainline, a 10 speed cassette & 135mm spacing, was outboard chainline bias. I pared the cassette down to 8 sprockets, and shimmed it outward, with the high gears I use most clustered on the biased end.


...My frame has a 68mm shell and I use one 2.5mm spacer per side as directed...
Shimano directions state 1X2.5 spacer on the NDS, and 2X2.5 spacers on the DS as a baseline on 68mm BB shell.

[ColonelJLloyd]

Don't think a 6800 shifter will have the proper cable travel for an XTR front mech.

Got it.

If a 6800 left shifter has comparable cable pull to SRAM 22 then I would try a SRAM XX FD.

[booglebug]

Yes looking for a FD with more movement for the amount of cable pull I have.

[ColonelJLloyd]

Yes looking for a FD with more movement for the amount of cable pull I have.

Bottom pull? What's the ST diameter?

[Gummee]

Yes looking for a FD with more movement for the amount of cable pull I have.

Try a CX-70 front. You can get em in top pull too

Works on my CX bikes with otherwise 6800/9000 anyways

HTH

M

[booglebug]

Lynskey Cooper CX, 34.9 ST, bottom pull, 68mm BB shell

[booglebug]

Try a CX-70 front. You can get em in top pull too

Works on my CX bikes with otherwise 6800/9000 anyways

HTH

M

Is this Shimano road, mountain?

[ColonelJLloyd]

Try a CX-70 front. You can get em in top pull too

Works on my CX bikes with otherwise 6800/9000 anyways

HTH

M

OP has yet to say what rings he's using, but he said it's an XTR crank. If it has stock rings I think that means a 38t (at most) large ring. The cage on any FD that is not MTB specific is not going to fit well (countour). I've tried a few setups and road or CX front derailleurs with cranks that use a 45t or smaller large ring will often hit the chainstay before they get close enough to the ring to shift well.

[ColonelJLloyd]

Lynskey Cooper CX, 34.9 ST, bottom pull, 68mm BB shell

I would try one of these (http://www.ebay.com/itm/SRAM-XX-2X-Front-Derailleur-35mm-Clamp-New-Never-Mounted-/232345707043?hash=item3618e22223:g:HJUAAOSwIQdZI2b Z). They are super light and should have the throw you need unless the 6800 cable pull is considerably less than SRAM 22. I use this with a 42/28 crank and it's flawless.

[booglebug]

XTR 42-28 and your right, the cage gets close to the chainstay but will clear.

[booglebug]

I would try one of these (http://www.ebay.com/itm/SRAM-XX-2X-Front-Derailleur-35mm-Clamp-New-Never-Mounted-/232345707043?hash=item3618e22223:g:HJUAAOSwIQdZI2b Z). They are super light and should have the throw you need unless the 6800 cable pull is considerably less than SRAM 22.

Does anyone know of a chart that shows FD travel per mm of cable pull?
Thanks for the help, you guys have gave me a lot of options

[HillDancer]

Try a CX-70 front...
The CX-70 is outside of its adjustment range when pared with the XTR crankset.

Does anyone know of a chart that shows FD travel per mm of cable pull?...
A SRAM XX MTB FD is narrower between the cage plates (8.6mm) than Shimano XTR FD (11.2mm), which make the XX less forgiving for shifter detents other than Exact Actuation. I would still try an XTR FD first, then adjust travel via cable tension and limiter stops.

[Corso]

FYI: Shimano 9 speed and 10 speed rear derailleurs have a different ratio of cable pull.

I used to think any rear Shimano d would be ok, thinking the pull was all in the shifter, but found out the hard way.

A nine speed will work with anything 9 and below. But not up to 10-11.

[GregL]

FYI: Shimano 9 speed and 10 speed rear derailleurs have a different ratio of cable pull.

I used to think any rear Shimano d would be ok, thinking the pull was all in the shifter, but found out the hard way.

A nine speed will work with anything 9 and below. But not up to 10-11.
A very slight correction: Shimano 9-speed MTB derailleurs work perfectly with 10-speed road shifters. However, Shimano 10-speed MTB derailleurs will not work with their 10-speed road shifters. That's where the cable pull ratio changed. On our family tandem, we have an XT RD-M761 rear derailleur shifted by an Ultegra ST6600 lever. The shifting is perfect.

Greg

[oldpotatoe]

FYI: Shimano 9 speed and 10 speed rear derailleurs have a different ratio of cable pull.

I used to think any rear Shimano d would be ok, thinking the pull was all in the shifter, but found out the hard way.

A nine speed will work with anything 9 and below. But not up to 10-11.

This is getting ugly but ROAD 10s sti shifts a MTB 9s rear der just fine. 11s road levers must have a road 11s front der or CX-70...no MTB front der will work. The crank needs to be not too far out and the rings need to be 11s' spaced.

[booglebug]

Shifted perfect with 6600 compact, chainring spacing and chainline is what I'm trying to overcome, not sure it's going to work but 10 speed FD got me closer then the 6800 FD

[dem]

Did you try running zero spacers on the DS? Wasn't clear if you had tried that above, or you just didn't want to.

Chainring spacing is the same for 10/11, so you're really just trying to get the chainline centered for the road derailler. I suppose another crazy option would be to figure out some way to shift the derailler outboard vs. the chainrings in. Maybe another wolftooth product opportunity!

(My XTR crankset is a 44/30, and the FD is at the lowest end of the FD clamp)

http://www.haphazard.com/bikes/gnargears.jpg

[booglebug]

Have 1 spacer DS and 2 NDS, felt a little uncomfortable with lack of threads on BB cup with more than 2 spacers on NDS

[HillDancer]

Assuming Shimano XTR BB93, 2X2.5 spacers on the NDS cup will leave only 3 useable BB threads, which is a valid reason for feeling uncomfortable.