2_i 

We have just acquired, within my family, a Brompton and I am setting up the lighting based on a Shimano dynohub. Could someone by any chance explain the puzzling feature of the Shimano dynohub for Brompton (DH-F703-SB), in that the drive side of the hub has a hollow with square teeth cut out? The photo below shows the drive and nondrive sides for comparison. The hollow, clearly, will accumulate dirt over time, so one would expect some function intended for it to balance the inconvenience.

fietsbob

Might be part of the assembly tooling, a connection, holds by that,

at the factory, to put the 2 parts of the hubshell together

around the dynamo mech.

wahoonc

I believe that is for fitting a roller brake. There is supposed to be a plastic cap to cover them if you don't utilize the brake.

Aaron

fietsbob

Nah, wrong side of the hub, electrical connectors are in that side,
the Right, on the bike.
besides these are narrow, 74mm axle folding bike hubs.
there's a Caprio version too, that Bike Friday buys to build
into their Tikit front wheels
inside, the dynamo core might slide into those splines, as well..
anyone want to tear one apart and post pictures

wahoonc

Duh!

Old age must be setting in

Roller brake flanges are external, as well as being on the other side. FWIW the hub I have, a DH-2R30-E, has the same splines, just never noticed them before. I wonder if they are for holding the hub to disassemble? An no I DON'T want to disassemble a perfectly good, operational dyno hub, besides mine is a bolt on and I am getting ready to take that bike to Ohio with me.

Aaron

2_i 

Well, checking the data in pdf for DH-2R30-E indeed reveals similar splines and that latter dynohub is specifically listed as working with a roller break, in spite of the splines appearing on the drive side. So this appears to explain the principal mystery. Brompton does not provide any cap to cover the splined opening, see their site. Regarding the width, it could be that there is no actual intention to employ a roller brake on the Brompton, but simply that dynohub was easiest to adapt for the Brompton. It is hard for me to pursue this speculation further, as I have no personal experience with the roller brakes.

Thanks for help in clarifying this far that puzzle.

fietsbob

Roller brake are a utility bike brake shimano makes , but only on 10cm wide hub types.
and fit on the left.. NDS, same as discs
https://www.sjscycles.co.uk/shimano-n...unt-prod17634/

the Schmidt hub made for folding bikes is polished and smooth, German, and costs more..

https://www.sjscycles.co.uk/16-(349)-brompton-front-wheel-with-hub-dynamo-w-o-fittings-son-qfwhubdyn-son-prod22349/

you, 2_i,
just may have to occasionally clean your bike, no way to engineer away dirt,
in the world made of dirt.

Stormclad

Hi all,

The spline on the RH side of the hub is the hub cap of the DH-F7 series of dynamos. In case of a fault, the internals can be replaced by just undoing that cap with a special tool, and screw a replacement unit in. All this, without having to destroy or unlace your original wheel. Of course, if the hub shell is at fault, you'll still need to despoke your wheel.

This should be the special tool.
https://www.sjscycles.co.uk/shimano-t...ool-prod24727/

Im not sure where you can get spare internals. Perhaps they are not available to the home mechanic but to the dealer.

This hubcap design is indeed from the DH-2R30-E. If you opt for roller brake, it is mounted of the LH of the hub. Not the right.

Regards.

wahoonc

Thanks Stormclad...given the price of that tool, I think a new hub would be a better deal! Not to mention the lack of repair parts from Shimano

Aaron

2_i 

Indeed, an astounding price for a coarse chunk of steel. Even when staying with SJS, for the money one could get 1 1/2 of a Brompton wheel built over that dynohub.

unterhausen

the regular shimano dynohubs have a 32mm wrench flat instead. While disassembling, you need to take that flange off because there is a big coil hooked to the axle. I'm hoping to take one of mine apart soon, there are instructions on how to do it floating around the internet. If it came to that, I suspect you could probably fake it instead of buying that tool. For example, I'm guessing a punch would work.

Stormclad

Yes, you could use a punch. But its like using a screw driver to remove a torx bolt. You risk damaging the interface.

You need to remove the LH locknut and LH Cone of any Shimano dynamo before you unscrew the hubcap.