pstock

I know (I think) that triple set ups require a good match of FD, BB axle and Crankset.
I had a decently running triple setup on my Rivendell road bike.
Speicialized "Flag" triple cranket + a 113ish axle and Deore FD-M730 (oh and shimano bar end shifters)

But I alsways thought that SPecialized "Flag" crank was a bit too special for my beater country bike.
So, when I found a discard frame with a decent triple FC-MT60 crankset installed I thought iit would be a good swap.

installing just the FC-MT60 on the existing 113ish BB axle left the small ring too close to the chain stay, it caught.

No problem I thought - I'll just retrieve the original BB off the donor bike. it should match the FC. It measures 122.6mm
but No, with the FC-MT60 and the 122.6mm axle BB installed everything on the DS seems to be too far out. the FD does not have enought Throw to reach the outer chainring (and it won't even shift into the middle chainring) even with limits all adjusted correctly (I think). the swing arm on the FD hits againts the frame and the FD collar too early.

for what it's worth, the gap between the inside of the RH crankarm and chainstay is 4mm further out (20mm versus 16) than the LH crankarm.
so, what am I doing wrong Now!?
do I need some spacers here to push the BB setup to the Left?

masi61

Why not split the difference and find a bottom bracket that is 1/2 the difference between the 122.6 and the 113 mm? That would be 1/2 of 8.4mm difference or ~4.2 mm? This would be like a 117 or 118mm spindle. I can't tell you who makes a square taper BB axle this length but eBay is your friend here.

oldbobcat

Not using a bottom bracket with a 115 or 118 mm spindle? I don't have the specs on your crank, but you can eyeball with the113 to see two more millimeters will clear the chainstay, and you can eyeball with the 122 to see four less millimeters will make the derailleur happy. Or you could test the 113 with shims, although I wouldn't ride the bike with more than 2mm. Or you could buy one of each and return the one that doesn't work, as long as you clean it up, save the packaging, and don't damage it. Just check with the shop first. Or you can go back to the Specialized crank.

dedhed

The original 122.5 spindle would have been a 32-52-38.5
https://www.bikeforums.net/classic-v...-question.html

https://www.retrobike.co.uk/gallery2...+m200.JPG.html

pstock

Good suggestions all. I'lll work on it more (fortunately I have a bin of spare BBs so one of them should suit)
I just assumed (Yes, I know) that a BB + crankset combination that was already on a frame and working correctly (and were probably the original set up) would probably work when swapped to another frame.
Bad assumption I guess (differences in the chainstay design?)

anyway, I'll try some mid-width-axle BBs.

I just thought/hoped there was me more science to this process (of Frame + FD + BB + crankset compatability) and less art/trial and error.

Peter

brooklyn_bike

you can put a 2mm spacer on the driveside with the 113 axle and see if it gets you enough clearance from the small chainring

Andrew R Stewart 

Having the crank arm ends centered, WRT the frame centerline, on triple cranks in a tall order and one that many bikes don't have. Even with double ones there often is a slight bit more offset on the drive side.

My first choice is to not use a spacer behind the drive side cup to achieve good ring/stay clearances. But I have done it and ridden many thousands of miles with this type of solution.

One trick is to loosen the drive side cup enough to "dry fit" the crank where the inner ring does have clearance and note that amount of loosening. This becomes the "correction factor" (times 2 to account for the non drive side which is included in an axle width spec) to better estimate a Bb with the correct drive side length. Andy

oldbobcat

There is, but not without the spec sheet for a 25 year-old crank.

79pmooney

Not all older BBs had symmetrical spindles. Many older Suginos did not.

For some of us, this is a blessing. My knees need the narrowest Q-factor they can get and do not care if my feet are skewed a cm or two to the right.

And yes, older bikes - BB spindles, frames and crankset - install, measure, replace with a spindle that "should work", measure and don't be surprised if you didn't get what you expected. (Or, install the crankset on a Shimano BB, measure and send your adjusted measurements, length and asymmetry to Phil Wood along with a bag of money and have them make exactly what you want. Shimano is very consistent with their BBs and right on spec. Phil Wood does very accurate work and their BBs have built in adjustability. What you will receive from Phil Wood will be gorgeous, last forever and be completely re-buildable.)

ShannonM

I'm running a Deore MT-60 on a Fuji road frame with a 68x118 mm UN-52 bottom bracket. 45/42/30. Shimano spec is for a 122.5 spindle, but I've had no problems at all. (I couldn't use the 122.5, because the road double FD I needed for the half-step didn't have enough swing.)

I bet a 118 would do you up right.

--Shannon