louky

I got a Trek bike on donation with some issues. Front shifter crashed so it has been ordered. The FD mounts in a way I haven't seen before. In the picture, you can see the derailleur doesn't mount with a clamp around the seat tube but appears to mount around the BB some way. I found FD here Shimano Acera M330 7/8 Speed Front Derailleur - E-Type - Cambria Bike that appears to be similar. I don't think there is anything wrong with the derailleur but won't know for sure until I get the shifter installed. What's the story on this type of mounting? Thanks!

soyabean

You can use any front shifter of any brand as long as it is the same range, either 3 speeds or frictions.

It's rather easy to eyeball any damage on a FD, hard to explain, pics/video would be better.

Crankycrank

At least one reason for that type of mounting is that the bikes seat tube is in a position that doesn't allow a traditional positioning of the clamp/braze on. Electra bike frames are a perfect example of needing something like this.....That is if they had ft derailleurs. Hybrid bikes | Trek Bikes

dedhed

What's an E-type FD

Andrew R Stewart 

Shimano saw the handwriting on the wall, about seat tube angles and actual presence, quite a while ago. So they set about to devise a mount that assumed on the BB shell and BB unit and not a seat tube at some angle. The E mount in the result that came first. A stamped steel bracket that was trapped under the fixed cup flange and held the ft derailleur. Shimano came out with other ft der mounting options later, like the direct mount. But as the riding public has embraced narrower gear ranges, for simpler shifting, der mounts are going by the wayside in any form. Andy

maddog34

this is simply not true. A BB mounted Front derailleur uses screws through the der. and mounts to the plate, not a frame tube.... this mounting style was also used by Specialized on their FSR/XC and various other MTBs. Any number of factors will prevent using a standard Clamp Type Der on a BB plate mount type bike.

Shimano Compatible Road Ft. Ders use a different pull ratio from Shimano Mountain Bike ft. Ders and they do not interchange.
Tiagra 4700 and some GRX Ft. ders have a different pull ratio and are meant to be used only with their matching Shifters.
Some Dura Ace derailleurs use a different Pull ratio from other Shimano Road and MTB derailleurs..
There are Multiple Cage lengths and Seat tube angles specified for different Bikes/gearings.

And SRAM is still sorting out what their Derailleurs should be... The ratios are all over the place and seem to change with almost .every new model lineup.

and i've seen several mangled Ft. Ders that LOOKED fine until they were checked for correct function... one would twist 20 deg. when shifted from small to big.. it LOOKED perfect. Another refused to move more than about half a gear-jump even with the stops backed all the way loose.... also, Two and Three Chainring Ders use different pull ratios and the newer one's cages vary dramatically in design.