msamsen

I知 building a touring bike based on a Salsa Marrakesh frame, which is an MTB chainlinenspec.

I want to use a drop bar and Shimano roadbike brifters, but will need to use an MTB crank and chainring setup due to the frame geometry.

To solve the FD pull-ratio compatibility problem, as I understand it, I have the following options:

1. Go with a 1x11 MTB chainring and avoid the compatibility problem. I can configure it with an 18-75 gear inch range. That is great on the low end, but translates to 20 mph at a 90 rpm cadence on then upper end. I'm not really sure that's an issue for loaded touring. And even for road rides with my wife, if I'm going faster than 20 I'm probably just coasting...

2. Use a bar end friction shifter on the front for a 2x11 setup and a brifter on the rear. I'm not sure I'd like a bar end on the rear, but as infrequently as I use the larger chain ring, maybe that's a compromise that I can live with.

3. Use a road FD with an MTB chain-ring, and a Shiftmate 7 for changing the pull ratio.

4. Use an IRD Alpina FD which I understand is a roadbike FD that is forgiving with MTB chainrings


Opinions? Other options?

base2 

Why not a vintage 9 speed triple?
Not everything has to be new.

msamsen

I知 not sure that solves the need for a MTB crank and chainring to accommodate the frame geometry. Am I wrong?

Also, I知 going with hydraulic disc brakes so those shifters don稚 work for me.

Thanks for the idea!!

dsbrantjr

Have look at Gevenalle's offerings: https://www.gevenalle.com/shifters/ Use a friction shifter up front and shift anything you want.

base2 

A triple is a triple is a triple. A 105 triple road derailleur will not care what triple crankset it shifts.

Trp Hy/Rd brakes would get you your hydraulics at a substantial cost savings when you start adding up the whole system.

msamsen

I may be wrong, but I don稚 think that痴 correct. Unless the 105 FD is different from current Shimano offerings, the pull-ratio of the Shimano STI road and mtn shifters are different. So, as I understand it, you can稚 mix and match road and mtn components on the front. (No issues on the rear.)

I壇 be happy to be proven wrong!

Then I壇 go with GRX components on the bars and XT on the driveline.

base2 

The shifters & the derailleurs need to have matching pull ratios. Having a "group set" is just a convenient means of catagorizing use cases.

Shimano 8,9,10 speed road/mountain rear derailleurs are interchangeable. Most people make the switch to mountain rear derailleurs for the additional capacity & larger mountain cogs. So the "9" of the 3x9 shifters I suggested is a "Go."

The front derailleurs are not always interchangeable. There are definite road fronts & mountain fronts. It depends on the vintage & group set. Others here would have more authority on the specifics than me. What I do know is it's easiest to match the front derailleur to the front shifter & save the compatibility trouble.

In this case, you specify you want a road brifter. So: road Claris, Sora, 105, or Ultegra, "triple" derailleurs are your options. All ought to work with the "3" of the 3x9 shifters I suggested above. So you are a "Go" there as well.

The crankset is built around a particular bottom bracket width. The spacing between the rings & chainline is the same. The primary difference is mountain has a smaller tooth counts across the board. But a tooth or 2 difference in gear diameter is insignificant as far as derailleur height/cage curvature is concerned. So buy the triple crankset that suits your fancy.

Where you often run into fitment issues is puting doubles on (68mm) mountain frames...They exist, & there is a lot out there. The larger diameter rings or narrower crank arm q-factor sometimes causes issues hitting the chain stays. It's seldom an issue going the other way.

If you have an issue with the triple road crank arms from a triple road crankset hitting the chainstays, you may be forced into a mountain triple crankset to move the pedals/crankarms wider...but I don't think that'll be an issue.

dedhed

the pull ratios of the road & mountain FD/shifters is different... but cranksets aren't incompatible. If the road triple FD ( shifted with a road brifter) can reach all the chainrings on the crank within it's limit screws, and can handle the chainring size differences, road or mountain crank doesn't matter.

70sSanO

Exactly what are you going to be running up front on your triple? Especially the granny.

John

msamsen

This is a build from the frame up. Just in the planning stage. I was planning to use GRX brifters with hydraulic discs. But, the frame (Salsa Marrakesh) needs a MTB crank as I understand it.

msamsen

Thanks again for all the helpful info.

I guess I wasn稚 complete with my design criteria. Here are some more parameters...

I was hoping to go with the GRX brifters, hydraulic disc brakes, and sub-levers. The choice of GRX is driven by the new ergonomics of the pivot point. If I知 unwilling to go to a different group to get a triple, then I知 limited to a 1X or 2X FD. I suppose I could compromise here as I致e ridden Ultegra for years on my roadbike.

The Marrakash frame simply does not accommodate a road 2X according to Salsa. They say, "...neither the 48/31 or 46/30 GRX cranks will work on the Marrakesh frame. Both the big ring and the crank arms will either directly contact the frame or be close enough to the chainstay that we cannot safely recommend it. The Marakesh frame would have been designed specifically with MTB cranks in mind..."

msamsen

To clarify, I知 looking at the GRX group which only has 1X or 2X FDs. A road 2X crankset doesn稚 work on the Marrakesh frame according to Salsa. They say, "...neither the 48/31 or 46/30 GRX cranks will work on the Marrakesh frame. Both the big ring and the crank arms will either directly contact the frame or be close enough to the chainstay that we cannot safely recommend it. The Marakesh frame would have been designed specifically with MTB cranks in mind...."

70sSanO

So, are you saying you want to run a 46-30? With 30t being to smallest tooth count? ... not something like a 22t or 24t?

John

dedhed

That's fine. the road FD doesn't care what crank is used as long as the chainline is such that it can reach the chainrings and handle the tooth differences being run, within it's limits. A road triple FD DOES care what shifters are controlling it.

Even then a person could come up with a way to move the FD out further with a spacer or something like this.
https://wickwerks.com/?attachment_id=9246

base2 

What we know, (as I alluded to above) is a road double is a "no-go" on your frame.

Then a triple crank is your only option then. I'd try a road triple crank, but that's just me & higher gearing. A mountain triple is probably the better choice for your intentions. It would still work with the 3x9 road shifters & road derailleur just fine.

I'm not impressed with 11 speed longevity or cost. But that is a seperate, unrelated issue. The issue is: GRX is not going to fit nor be compatible with your frame & does not offer the gearing range you seem to want.

70sSanO

Okay, this is just food for thought. I'm not saying to go do this.

My wife got a bike with a triple 30-39-50. It uses a Tiagra 4603 front derailleur. She is never going to use that 50t, so I swapped out the 50t for a 46t. I thought when I checked the Shimano specs were minimum 50t, but if I don't talk in front of the bike it won't know. It shifts great.

You are not going to use a triple, but "if" you are using a 46-30 double setup, it just "might" work with a triple road FD and you can use road brifters. I might have been able to push it to a 28t. Tiagra is not at the top of my list, but since it works it is staying.

The one thing I'm not sure about is the overall throw of the derailleur and whether it will reach far enough with the MTB crank. But, I think your Marrakesh has a 31.8 seat tube. Once upon a time, I took a 34.9 FD and offset it on a 31.8 seat tube. I think I used 34.9 to 28.6 shims and filed/sanded them and effectively moved the derailleur off-center 3mm (no shim at the furthest point). If you have access to a machine shop you can make a slick aluminum setup. There also may be a Problem Solvers clamp-on for braze-on front derailleurs, or you can find someone to make a one that pushes the FD out.

Will it work, how do I know? We can all dream.

John

msamsen

Thanks for the additional ideas! I’m still noodling...

All clever input is appreciated!!

Mike

tFUnK

Not seeing what your ideal setup in mind would be? Do you have a certain gear range that you'd like to accomplish (whether that's 1x, 2x, etc)? It's been shown that a 1x setup can cover nearly the same range as a 2x or 3x.

msamsen

I looked at a 1X. One goal is to have a lower gear of around 18 gear-inches. With a largest spread 1x11 chain ring I can find, that results in a top gear of only 75 gear inches or 20 mph at 90 rpm cadence. That痴 not necessarily a killer for loaded touring, but there are times when using the bike as a gravel bike unloaded, that I might feel constrained.

tFUnK

Gotcha. Well, one scenario is to run 1x with something between 32-38 up front and go with a 11-50 cassette. It will get you close to your ideal. Yes there will be some gaps larger than you'd like but I have large range cassettes on a few of my bikes and for the most part I am not bothered by the jumps. Having said that I'm in the process of cannibalizing some other close range cassettes to get smaller jumps on the high end (all this on 10 speed setups).

dsaul

Salsa sells that bike complete with Sora shifters and an Alivio Trekking front derailleur. I found that Shimano has a line of Trekking components that seem to be MTB components(with a "T" added to the product number) that are designed to work with Road shifters. The front derailleurs are all made for triples, but will shift a double. The shift cage is made for a wider range of chainring sizes, so they should work fine with an MTB double like the XT with 38/28 chainrings. https://bike.shimano.com/en-EU/compo...erailleur.html.

70sSanO

Shimano Trekking groups were generally not available in the US, but beyond that the front derailleurs are not compatible with road shifters. The are basically slightly revised MTB components.

Off-topic... I will say that for anyone still using V-brakes and wants 3 finger flat bar brake levers, the trekking levers are nice. The XT ones (BL-T780) are really hard to find, but the Deore (BL-T611) are still around.

John

Fungo

I am in to touring, bikepacking & commuting these days. I have a hardtail mtb frame w. 120mm suspension that I run 622x38 or 2" tires depending on sand, gravel, mud etc. I have it set up with old dura ace triple brifters. Front derailleur is generic triple & works with a mtb crankset w. 48/ 40 / 24 rings w. 9 cogs on the back 11-32. It works pretty well, although I will change the low chainring to 22 or up the big rear to 34, sooner or later. (quality 9 speed cassettes are expensive.)
I just rebuilt a gravel frame with 3 x 9 drivertrain. My boneyard collection of dura ace & micro new 3x brifters won't pull the chain through more than 2 rings . I ended up putting trekking bars on it with micro new 3x 9 mtb shifters on it. Front crank is mtb 22 / 40 / 48 set up. Just rode it around the hood & it seems smooth. This rigid fork bike has 40 mm tires on it now, but will probably go to 32's & use it for commuting & hard pack / paved touring. The front derailleur is vintage Deore XT, top pull. It doesn't line up perfectly due to a slack seat tube angle. Also many of my boneyard mech's won't fit because seat tube is too close to rear wheel. But this build shifts well, not racing well, but it is smooth and the step from top to middle ring is sweet. I haven't given up on drop bars but this set up is interesting and I like the gear range.

maddog34

Be aware, not sure if it was mentioned... GRX uses the dreaded Tiagra 4700 pull ratio on the front Der....they do not mix with any other groupset that i know of.

Leisesturm

This is what the o.p. be wantin', arrgh ...
[Edit: for some reason my browser balks when I go through BF, override the caution if you get blocked. It's ok. I promise.]