Hi everyone, I'm a new member to these forums but have been a reader for years. I decided to join up and start this thread because I can't find anyone who has tried fitting an e-type front derailleur to a Brompton. Can anyone think of a reason that this wouldn't work?
I believe the main difficulties with fitting a front derailleur to a Brompton are that the seat tube is too wide to fit a standard derailleur and any derailleur that is fitted fitted needs to be rotated in order to compensate for the fact that the seat tube is offset from the centre of the cranks. I'm aware of the SP front derailleur hanger that solves both of these problems, but from what I can tell an e-type should do the trick too and these can be bought cheaply online. An e-type is mounted to the bottom bracket, so it should line up with the front chainwheel without needing to be rotated.
The problems that I can envisage are:
1) E-types are normally anchored to a mounting bolt on the seat tube to help keep them in place. I've read that you can get away with not fitting this. Alternatively, the e-type could be rotated around the chainwheel so that it lines up with the seat tube and secured in position using some sort of hack.
2) The largest chainwheel that is compatible with an e-type is 44t. Not a problem, if like me, the aim is to get more low gears for hills. Also this could be compensated for to some extent by fitting a 12t rear sprocket.
Can anyone see a hole in any of my reasoning? I don't have any experience with e-type front derailleurs so maybe I've got it all wrong. It would be great to hear from anyone who has tried this approach.