crankset and front deraiileur compatability
 

I have a long haul trucker frame that I am building into a gravel bike for me, I want low gearing. I am very small, the longest crank arms that I want are 165mm. I am looking at several possibilities:

FSA CK-316 JIS Crank Crankset 165mm 44/32/22t . The upside is cheap. The gearing is pretty much what I would want. I have no idea on the reputation or quality of this set.


Shimano Deore XT FCM780 10speed XT chainset HollowTech II 42 32 24T 165mm. Pricier, and maybe too low on the top end.


Sugino XD600 26/36/46, 165mm. Nice enough gearing (though it would be nice to have a 22 or 24 on the bottom. Price is right.

Sugino XD2 Crank, Triple 46x36x24, 165mm. Now my preference. Pricier than the XD600.

So, how do I figure out what front derailleurs will work with these? The Deore/mountain set is easy, I'd just use the mountain derailleur. How about the other two? Any comments on the FSA crank? I know nothing about them.

Shifting isnt an issue, I will use bar end shifters. Unless I go Deore I probably will build this as a nine speed. I see the specks for the Sugino XD600 crank that it is designed for an eight speed chain, so I guess I would have to go eight speeds if I go that route. I see that figuring out what bottom bracket to use is very confusing. Maybe that will be my next question. (Surly's specs are for a 110 using a similar crankset).

Front derailleurs don't care about crank brand. They mostly care about chainring size and are designed around ranges for largest ring which affects the height and curvature of the cage, and the inner (or granny) which determines how low the back (low) end has to be to clear the chain. There's also some loose correlation between cage width and chain width, or chainring separation, ie 9s, 10s etc.

Mtn FDs are usually designed around outer rings in the 44-48t range, with grannies as small as 24t or up to 24t smaller than the outer. So your Deore should be spot on for your needs with any of these cranks is fine, and if you want a 24t inner you can always buy that separately and install it.

To go smaller than 24t would require a crankset with a granny BCD smaller than 74mm.

seems between road 53t Road, and MTN 42t there is the Trekking 48t group seen thru Shimano's European catalog

havent kept up .. Did get a Deore for 48t, but that was many years ago [ thumb shifters are friction so that compatible issue is moot]


after its yours you can change chainrings from whats in the package.


5 bolt 74 bcd 24t, 58bcd 20t I forget what the 4 bolt ones are.. 64 22t?

FDs are more pushing the chain between toothed-Planes of varying diameters , Brand is pretty immaterial.

I'm not knowledgeable about "road stuff", but aren't bar end shifters "road" shifters?
IF so, the FRONT shifter pulls a different amount of cable vs mountain shifters and requires a "road" FDER.
IF friction, then no problem.
Problem is "road" FDER's are designed for 50T+ large rings.

Someone please correct me if I'm wrong.

the pro race use is sticking them in the front of aero bars , these days.. in the Tri' bikes & time trials..

the touring rabble puts them in the back of Drop Bars.

left one to the front D is friction . (MINE, both are)

GP put bar end shifters in the BS MB1 specs for a while..

Aren't all bar end shifters friction on the front? I assumed because they were friction there would be no compatibility issue.

Thanks, I think I will be good with a 24t as the small ring.

For knowledge purposes, if I wanted to use road/STI shifters I assume that I would need a road front derailleur. Are they any that work with the Sugino touring cranks? Don't go out of your way to figure it out as I do not plan to go that route. I am just trying to get my arms around the options.

I'm sure Shimano offers some kinf of road triple hybrid or touring derailleur, but I couldn't point you toward any specific model. OTOH, as you pointed out, if you use friction or micro index you're free to use any derailleur that will handle the range.

I have no working knowledge, yet, but am under the impression a Tiagra FD-4503 will work and the FD-CX70 is also reported to work even though it is for a double. I am in the process setting up an xt triple with a Tiagra FD-4503 front derailleur and 105 STI brifters hopefully I'll know more this weekend, im still waiting on the cables to arrive and really hoping it does work. If not I'll try the FD-CX70 next. If i were starting over I'd try the FD-CX70 first because I like it a little better for some reason.

Watch out if you go with a 10sp crank as these are spaced differently than 7/8/9 which are all basically the same. 10sp dyna-sys is narrower and requires a 10sp derailleur. The cable pull is the same, but the derailleur compensates by moving less.

On my 10sp shifter set, the rear shifter is designated as Dyna-sys, but the front is not and works with my old 7 speed front. If you are using friction shifters all this is moot.

I believe you are correct. I am planning on running a 10 sp setup consisting of 105, 5703 brifters. M771 9sp crankset, a Tiagra 4503 FD and a 9 sp xt rear derailleur. As soon as the cables arrive I'll report on the viability of the system.

Rivendell says that the XD2 crank is fine for up to nine speeds. My experience confirms this.

Si' lado izquierdo..

Is it the 10spd crankset that is spaced different, or the 10spd chainrings? Thought I read somewhere the [Shimano] cranksets were spaced the same, but the chainring mount tabs were redesigned to compensate for the thinner chain. Upgraded my 2000ish 105 3x9 tandem to DI2 and solved one of the front shifting issues by swapping to "10spd" chainrings. Certainly could be wrong, just curious.

Okay, I'll follow up with my current experience. I'm building up an AWOL frameset and all is done but the front mountain triple 44/32/22 with Tiagra 4503 is not working well at all. It seems the FD does not quite swing out far enough to easily engage the big ring. I tried switching the hollowtech bb shims from the default 2 on drive side and 1 on non drive to 2 on non drive and 1 on drive. Measured distance between center of seat tube and inside face of middle chainring is ~47.5 mm in the non standard configuration and I can get the system to just barely work but must heavily tension the shift cable in the low position to do so and the derailleur is against the outer extent of the swing when on the big chainring. Issue 2 is the lower end of the cage just barely clears the chainstay and the amount of tension on the cable tends to pull the derailleur down the seat tube. At this point I'm looking at a CX70 FD but am not sure it will have enough swing either as it's made for a double.

Another thing I'm considering, I'll check the chain clearance when I have time... Is to nip a little off of the lower portion of the cage to give more chainstay clearance, (if it doesn't create a clearance issue with the chain on the large ring), then tack weld a piece across the bottom to stiffen the cage. I'm thinking I don't have much to lose at this point as I believe, but hope someone here proves me wrong, that I've exhausted all possible options to get this setup to work.

Anyone have any advice?

Assuming you are using STI? Without moving to a flatbar/mtb-shifter setup, or friction, your best bet is IRD Alpina-d Compact Road Triple Front Derailleur - Harris Cyclery bicycle shop - West Newton, Massachusetts

This looks like it might be the ticket! I do have a set of bar end's so I may also consider switching to a thumbie and run the FD in friction mode. I just really like the idea of brifters. The build has gone very well, except that I can't get the FD to work. I'm itching to get this together before the cold sets in but at this point I doubt that will happen.

I think part of your problem is the FD is designed for a 50-39-30 crank.

Do you have the option of friction shifting the front? If so, get a FDER designed for the ring sizes you have.

A shot in the dark, but K-Edge (and FSA used to but may not anymore) and a couple tandem manufacturers like Co-Motion and Santana maybe make FD clamps designed to move a DI2 FD outboard for tandem or triple-to-double conversions...May move your FD outboard and allow getting the outer ring without so much cable tension against the FD's outer limit.

May also allow spacing your cranks back out and avoid chainstay clearance issue.

I'm searching for one now, if I can find one it seems like it would be perfect match for the IRD FD even though my setup is still 2 teeth out of IRD's spec.

Understood, but the Tiagra 4503 is widely reported to work with mountain triples. I fall in the it doesn't work category.

Bare in mind that 48t and 46t would be considered mountain bike big-rings. Going all the way down to 44t, you are really pushing a road derailleur to the limit. Not saying that it can't work but when you are on the fringes of a component's design, slight differences in seat post angles and chainstay length will start to matter. If you want a second opinion, we can meet up sometime, I'm in Pgh frequently enough.

I doubt that the 2 tooth difference on the IRD would matter.

I may take you up on that.

FWIW, I think I have 2 potential issues keeping this from working as it should. The FD is at the limit of it's throw when it's on the big ring and I have to tension the heck out of the cable to coax it that far out. If I could cheat the FD 3mm out I believe everything will work, albeit not as smoothly as it should. The other potential issue is the lower end of the cage barely clears the chainstay. As a last resort I'll run a thumbie for the front but I really hate the thought of doing so.

At this point, I'm thinking I'll bin the Tiagra and get the IRD, if it doesn't work then thumbie it is...

How much space between the big-ring and the FD cage? Make sure it is as high as you can possibly get it without the chain rubbing the bottom of the derailleur cage when you are in the granny. In your case, I'd actually select height based on where the FD sits when you are in the small ring.

I think I was in the neighborhood of 3 to 5 mm up. It shifts pretty well but I have to have a ton of tension on the cable to the cage over the big ring. So much so that the FD tends to slide down the seat tube, I don't want that and I don't want to crank too hard on the derailleur clamp. If I loosen the cable to what I believe to be normal it won't pull the FD over the big ring. Someone suggested taking a dremel to the hard stop on the FD which I may do after a couple of days of pondering.

On your first problem, yes, a mountain bike crank is a squidge wider than a road crank. Try removing the spacer on the drive side entirely, then reset the front derailer. You shouldn't need 3 spacers on the nondrive side. You can also use thinner spacers. Your local bike shop should have some or they can get them for you. You can also find them on-line

On your second problem, if the derailer is slipping on the seat tube, you haven't got the clamp tight enough. It shouldn't move at all, no matter how much tension you put on the cable.