dabac

Hi all,
Well, the headline says it all really. Am looking to buy a new (MTB front) derailer, and suddenly realized there was another option I hadn't considered. Never used a BB mount before.

The BB mount seems somewhat neater, but I imagine alignment might be trickier.
Seat tube mount is an old aquaintance; I'm not worried about any surprises there. It's certainly worked well enough before.

Any preferences, tips and pointers, let me know.

Cheers,

CACycling

BB mounted FDs are typically used where seat tube mounting is not an option (such as on 'bents). Not sure why you'd use one if seat tube is an option.

dabac

Neither am I. But having the option open increases the number of possible candidates when bargain hunting...

HillRider

Bottom bracket mounts are usually limited to suspension MTBs and other bikes where the seat tube is not round and has no braze-on mounting tab. Also, check to be sure the bb mounted derailleur has the cable pull from the correct direction as many MTB's use a top pull arrangement and that's unusual on road bikes.

Me? If a seat tube clamp-on or a braze-on adapter fits, that's what I'd use.

fietsbob

Then you have to consider the Big ring size you want to run.

2 schemes decide that for you.. BB mount ,
and where a braze on mount is fitted on the seat tube.

HillRider

Good point. BB mounts usually assume a MTB crank and a 42 or 44T big ring and you can't adjust the derailleur high enough for a typical road 52 or 53T chainring