stargazer48

I've been meaning to install a front derailleur on my steel Swift frame. I already have a double chain ring (54/39). Although, I have yet to use my 39 granny chain ring, I want a FD, to prevent the chain from popping off which it does occasionally and use it to shift down to the 39 (which may be rear) and back up to the 54 when I am done. It appears that a top pull FD would be preferable due to the frame design. The road bike FDs are bottom pulls while Mtb FDs are top pulls so Mtb FDs are the way togo but their specs limit the chain ring max to 46 to 48 depending on the derailleur.
I have posed the following question to the Nashbar Tech support but have gotten opposite answers.
Even though Mtb FDs have a max of 46 or 48 size rings, will I be able to use them with my 54/39 setup since I don't plan to shift beackand forth that often? One guy said you can but it won't be a smooth shift which is ok with me, while another said it probable won't work do to my size ring.

Can anyone shed some light?

Thanks

maunakea

Two factors: 1) the "capacity" spec, largest chain ring T minus smallest chain ring T. Each FD has a capacity spec, many Campy road RDs are spec'd at 15T capacity. May MTB FDs are speced higher, e.g., 22T capacity ... but 2) cage design is the second factor ... each FD also has a max chain ring size for reliable shifting, and MTB FD are rarely higher than 48T. I think you'll need to build it and see if it works. NB is really good about returns as long as the part and packaging are pristine.

stargazer48

Anyone else care to comment if a Mtb front derailleur (max 46T to 48T) might work on the Swift with 54T/39T (15T spread) based on my limited requirement?

geo8rge

The geometry of the tubes might make a FD impossible. email Swift to see if they have any advice, they sell custom bikes so they may have mounted some themselves.

SRAM duel drive rear hub, or the (I forget the brand) internally geared BB might solve your problem for more $$ and less time.

If you are looking for a lower gear, the shimano mega range thread on freewheel&cluster has treated me well. The mega range might be the easiest upgrade for you. Infact I ditched all but one chainring (44t), although I mostly use my bike for commuting and riding on relatively flat terrain, I have used it for 'touring' day trips on hilly and steep rides. This would not work for real touring ie hauling alot of gear (tents, extra clothes, full tool kit, sat phone, ...).

maunakea

https://www.schlumpf.ch/sd_engl.htm
Not an intuitive site. select the product across the middle, then use dropdown menus.