[SOLVED] [Brompton] Adding a front derailleur: Clamp?
 

Hello

I currently have a 34/50 double chainring on my six-speed Brompton, and would like to add a derailleur so I don't have to stop and move the chain by hand.

Someone used one of the following clamps to do just that on a Dahon:

• LitePro Braze-On K-Series Front Derailleur Clamp Adapter For Dahon K Frame
• LitePro P-Series Braze-On Front Derailleur Clamp Adapter For Dahon P Frame

Any idea what the difference is between the K and P Series, and which one is more likely to fit a Brompton, whose seattube measures 38,55mm?

Thank you.

I have one custom Made Of steel which takes a Road Braze on Front derailleur (Sell in U$D 100)

I believe Steve Parry who shows up probably at all BWC final race weekends Makes some in UK .

There has been some development around fat bikes, of the so-called direct mount front derailleurs and adapters for them. You might look into these whether they might provide any extra options.

I believe the LitePro K-series is 40mm while the P-series is 41mm. Seems like you would need to use a shim. Sram seems to make a front derailleur clamp of 38.2mm. Good luck with the conversion and please let us know if it is possible.

I have seen some front derailleurs for Bromptons where they used the old type of front derailleur that was held on by the bottom bracket..

Of course you may be limited in how big a chainring will work,, those were for a much larger MTB wheel.

correct

Thanks much for the infos. I'll look into those two options, and see if any would make it possible to install a derailleur on the Brompton.

https://fat-bike.com/wp-content/uplo...t3-600x460.jpg
https://fat-bike.com/2014/01/boreali...illeur-do-dad/

I ordered the "LitePro Braze-On K-Series Front Derailleur Clamp Adapter For Dahon K Frame".
http://i.ebayimg.com/images/g/61MAAM...K4c/s-l400.jpg
http://www.ebay.com/itm/222154907485

Incidently, what Dahon bikes use the K frame, so I can check what they look like, especially their geometry (seat tube ↔ bottom bracket)?

Thank you for posting. Now keep us updated :thumb:

Just arrived this morning. It's the right diameter on the seat tube, no need to add a piece of inner tube to fill it.

I'll stop at a DIY workshop and play with old, bottom-pull derailleurs that might work. The clamp has a cable housing stop.

In the meantime, does someone know which Dahons use the K frame, so I can check how their seat tube lies compared to the bottom bracket?

The K-series includes the Speed and Vitesse frames.

Thanks for the info.

On that frame, the seat tube is also located a bit behind the bottom bracket, like on the Brompton. Looks good.

http://revolutioncycles.com/images/l..._copy_09_z.jpg

Please keep us updated. I'm curious if it'll work.

Hello

I've done that on my Speed
http://i97.servimg.com/u/f97/16/84/74/48/derail10.jpg
Take an old FD with 34.9mm clamp, enlarge it to 40mm using a steel cylindre and a vice, and use a collar as a stop. It's rather heavy, not really handsome, technicaly incorrect, but work well and cost less than 5€.
On a B it would be a kind of waste, but it's a track for a solution.

Thanks much for the info.

At this point, I know I should get a braze-on, bottom-pull FD à la Shimano Ultegra 6700, but there remains the question of whether it'll fit against the downtube of the Brompton.

As for the clamp, I was told 3D printers can now manufacture metal parts for a reasonable price. I'll ask around for a quote and see if I can build a model with a CAD application.

After grinding a couple of spots on the LitePro K clamp with a Dremel mini-drill where the Shimano Tiagra FD rubbed against it, the derailleur seems to work OK :thumb:

The last step is getting a (friction?) thumbshifter and running it to the derailleur.

I notice that the cable will run at an angle instead of vertically between the derailleur bolt and the cable housing stopper on the clamp. The derailleur bolt is located approximatly 25mm to the back, and to the right when using the inner chainring while it should be almost vertical when using the outter chainring.
Is that a problem? Is there a better way to somehow wire the derailleur and the shifter (if need be, I don't mind installing the shifter close to the derailleur instead of on the handlebar)?

I attached some pictures I found on the Net.

Thank you.

Salut, pourrais-tu mettre la version VF stp ?
(could you put the french trad please ?)

Tu peux utiliser un shifter triple quelconque récupéré sur un VTT/VTC, ou une poignée tournante. C'est pas bien dur à trouver et assez peu de problèmes de compatibilité)
(you can use a triple shifter from a MTB, or a gripshift, it's easy to find and usualy compatible).

Done :beer:

No Spielberg yet. Working on it.

Cool!

Nice! Well done.

Now take a close look at the third picture from the top plus picture number seven: https://www.facebook.com/photo.php?f...type=3&theater

The 10 speed (now 6 speed) Campy Brompton. To avoid breaking the front derillium the owner removed the screw holding the der together (not all der`s has got that screw, some are riveted). I do not remember exactely what he said, if it was when using the small chainring or when folding the bike there is danger of breaking the der but this mod is important, at least on the der he used.

He also said nobody is allowed to borow the bike since there are so many things that can go wrong if used by a person who does not know the "seecrets" of making it all work.

I`ll see if one of my own pictures of the bike is a better close up of this mod.

Is it available commercially?

Thanks for the pics. I assume it's a custom-made clamp from "Vincent van Eerd at Eerder Metaal & de Brompton Winkel". I'll drop them a mail and ask 1) if they could make more and 2) how much it'd cost.

I'm also thinking of sawing off the lower part of the fork, as someone did here on a Campi derailleur: https://www.facebook.com/groups/Lond...2%3A%22R%22%7D

For that reason, I do recommend getting a derailleur whose fork is screwed together instead of riveted.

Removing the bottom of the cage certainly looks important given where the chainring is in the photo relative to the derailer bottom. Without removing it, the chain would be hanging on it. A "fast" fold would probably bend the derailer or mount over time.

Steve Parry UK, and as you say Vincent van Eerd in NL, may be something you would find in Europe,

mine came thru the original Brompton dealer in the US, Fold a Bikes, in Palo Alto Cal [Home of Stanford University]

he has since retired , selling the house probably gave him a fortune, given the real estate bubble in that area..

.. or break the derailer bottom....

Do`nt ask me how I know this.. :cry: