Expanding Brompton Front Fork

[ShlomiMir]

I was wondering how one would go about enlarging the 70 mm Brompton front forks to the 100 mm needed to install most front hub motors.

I've seen terms such as "rebrazing" in the forums, but I don't really understand the process.

Could anyone enlighten me? Also, has anyone specifically worked on the Brompton, and if so, what side effects does it have on the bike and/or the fold?

 

[Miles]

I believe there's now a narrow (70mm) version of the Tongxin motor http://www.tongxin.net.cn/en/product.htm - might be worth enquiring about that, first.

 

[dogman dan]

Wow, that sounds like a lot of expanding. What about just finding a wider fork that would fit? Are bromtons that exotic that another fork wouldn't fit?

 

[Drunkskunk]

if it's the titanium Bropmton fork, then there's nothing that can be done. If you have the chomoly it would need to be rebrazed with probably a wider crown to clear the sides of the motor. a 16" wheel would have a steep angle.
On the other hand, you could get a new fork, either from a kids bike, or more likely from a recumbent with 100mm spacing for a 16" wheel. it should be much cheaper than trying to have your fork modified..

 

[ShlomiMir]

Wow, that sounds like a lot of expanding. What about just finding a wider fork that would fit? Are bromtons that exotic that another fork wouldn't fit?

I agree, and I would also like to know the answer. Has anyone switch forks on a brompton?

 

[Mathurin]

I believe there's now a narrow (70mm) version of the Tongxin motor http://www.tongxin.net.cn/en/product.htm - might be worth enquiring about that, first.

Also there's the 2X clytes, like the 208. Velectris used to have these when they carried crystalite but if I'm not mistaken they have 9cont to fit folders these days, and there must be some other vendors that have them also. But certainly, there's other solutions then modifying your fork to fit a hub motor.

 

[nathan_jones]

ben at kenetics.co.uk makes wide brompton forks