Regular bike derailleur for a Brompton?

[Fastpedaller]

I've seen there are rear derailleurs from the Far East which appear to be copies of the P-line item - I view them with some scepticism. Has anyone here fitted a 'regular' derailleur to a Brompton? I'm asking this because the jockey wheels on my 2007 (but less than 300 miles) superlight give the impression they are fragile After just 20 miles of being caught in the rain a couple of weeks ago I had to clean and lube them. Even thogh a standard derailleur may be positioned a bit lower I imagine the jockey wheels will be more durable. I offered up a Shimano Acera mech from my spares, and suspect it would fit the bill if used with an old style bolt-on hanger in place of the Brompton tensioner. In use (especially with close-ratio sprockets on my 2 speed (now 3). the cage will be almost horizontal and pointing forward, when folded it should point rearward. There are 2 snags I've seen though ...... the tension seems a lot higher than the B tensioner and more seriously it looks like the mech will clash with the front wheel upon folding. I wonder if a Shimano shadow type or Sram will be slimmer?

 

[rualexander]

Don't think any regular derailleur will have enough throw to take up the slack chain when the bike is folded.
Some folk have added an extra section of wire loop to deal with this though.

 

[brommieinkorea]

Why ? Regular derailleurs are so close spaced they're a nightmare to keep working properly. My Bromptons have yet to wear out a jockey wheel although they can somewhat pack up with dirt. 3500 miles on 2 Bromptons this year, and the 6 speed drivetrains are the one thing working flawlessly. I would love to be able to do a long term test of the new 4 speed derailleur on Brompton's dime though.

 

[u_i]

I've seen there are rear derailleurs from the Far East which appear to be copies of the P-line item - I view them with some scepticism. Has anyone here fitted a 'regular' derailleur to a Brompton?

I ride with an H&H Advance derailleur on C-Line, which works great. It's far better than the pusher.

Why ? Regular derailleurs are so close spaced they're a nightmare to keep working properly. My Bromptons have yet to wear out a jockey wheel although they can somewhat pack up with dirt. 3500 miles on 2 Bromptons this year, and the 6 speed drivetrains are the one thing working flawlessly. I would love to be able to do a long term test of the new 4 speed derailleur on Brompton's dime though.

As @brommieinkorea mentioned, the standard derailleurs fail to gather enough slack. LTwoo put out a standard-type derailleur for Brompton that works on the edge in gathering the slack; some people are happy with it.

 

[Schwinnsta]

I ride with an H&H Advance derailleur on C-Line, which works great. It's far better than the pusher.


As @brommieinkorea mentioned, the standard derailleurs fail to gather enough slack. LTwoo put out a standard-type derailleur for Brompton that works on the edge in gathering the slack; some people are happy with it.

How many cogs do you have on your rear hub?

 

[u_i]

How many cogs do you have on your rear hub?

4 on a Brommieplus freehub. 3 fit on the original Brompton. Judging from the space there, a longer freehub than the current Brommieplus could be made that might accommodate 5.

 

[Origamist]

I run a Shimano Saint 10 speed derailleur on my Kinetics Brompton (135 OLN) and use a bungee cord to take up the chain slack when folding/unfolding

 

[Schwinnsta]

I wonder if the reason Brompton did not go with a standard derailleur type on the G is due to their requirement for chain retention in all gears.

 

[Kell]

Why ? Regular derailleurs are so close spaced they're a nightmare to keep working properly. My Bromptons have yet to wear out a jockey wheel although they can somewhat pack up with dirt. 3500 miles on 2 Bromptons this year, and the 6 speed drivetrains are the one thing working flawlessly. I would love to be able to do a long term test of the new 4 speed derailleur on Brompton's dime though.

I've had to replace the chain tensioner as the jockey wheels were both worn down on the cogs and also loose on the spindle on top of that I've also had to replace the metal chain pusher on mine.

It was a few years back so not sure how many miles that was at.

 

[Kell]

I've had to replace the chain tensioner as the jockey wheels were both worn down on the cogs and also loose on the spindle on top of that I've also had to replace the metal chain pusher on mine.

It was a few years back so not sure how many miles that was at.

Found the post - it was two years ago.

This is how worn my chain tensioner was compared to the new one:


View: https://www.youtube.com/watch?v=8O5NcDeyDu8


And this is what the chain pusher looked like.