7802mark

I'm planning to convert an old bike to 27 speed (3x9). The planned chain rings are 48, 36, 26. Planned cassette is 11-34 9-speed. The planned FD is the IRD Alpina-D.

The frame routes the RD cable over the top of the BB and top of the chain stay. I suspect the bottom of the FD cage may snag the RD cable. I notice on another bike that the Alpina has plenty of extra room at the bottom of the cage for chain clearance with these chain rings and the cassette. The cage could be shorter and still clear the chain. Question: What FD would shift 48, 36, 26, yet have a shorter cage than the Alpina? Will be using friction shifting, so index compatibility isn't an issue.

Thanks in advance for your suggestions.

HillRider

I had the same problem with an '85 Bridgestone 400 when I changed the crank to 46/42/26 and the Sun Tour ARX fd's tail was very close to the top chainstay routed rd shift cable. I expect a road double fd might work and, since you are using friction shifting, trimming it to clear the chain in all positions should be no problem.

gyozadude

You can explore the possibility of a cheap Shimano triple FD that specifies 42T max. E.g. Shimano TX50 TS/DP 42T. See: https://www.niagaracycle.com/product_...oducts_id=6380 for an example. This will have a shorter cage for better clearance of things like chainstays on small, compact mtb triples. You probably noticed also have the option for Top Swing (TS) or Bottom Swing (BS) FDs. Traditional FDs are Bottom Swing with Top Pull. If you had clearance before with a larger T-crankset, you're probably okay with the same style of TP/BS FD. If you had issues where the clamp was straddling the seat tube water bottle braze-ons, then you can think about switching to a Top Swing FD, which may sound confusing, but it places the clamp lower at about the height just below the level where the teeth on the big chain ring start. Most cheap Shimano triple FDs have multiple clamp adapters to fit most seat tube diameters plus many are Dual Pull, so they accommodate cable pull either way, although, if your FD cable routing is above and to the left of the BB shell, the top swing FDs, due to sitting lower toward the BB, might not give you a very good cable pull angle from below. YMMV.

fietsbob

FD? , I use the same one [different from yours] on 2 bikes,
older frame cable above the BB the big ring is 2t larger
than the one with an under the BB cable guide..

So another option, .. Change the big ring to come up
to within 3~5 mm of the lowest placement your FD can sit.

then you hardly need that 11 t top cog,
50/12 or even a 52/13 should be good enough

Booger1

I have a old Shimano long cage derailer on my touring bike,not sure of the model.Works fine with 46-34-20.It's close but it doesn't hit anything.