roza

Hello.

I can get a second hand ( but new/unused ) nexus inter 8 hub for a bargain price.
But it is a di2, roller brake hub. I don`t want electronic shifting & I want a disc brake.

I had a good look at the hub & all the info i could find on the net.

I am fairly certain I can make a custom manual shifter&shifting mechanisam for this hub... possibly a dual pull/cable style... since as I understand di2 hub doesn`t have a return spring. Are there any other differences I should be aware of ?

I am also fairly certain I can fit a 6 bolt disc brake rotor to the hub with the use of a custom adapter that would fit the roller brake interface on the hub.
Suppose i can do that... could there be any other issues with using a disc brake on a roller brake hub?
Is the interface geometry the only difference between a disc nexus 8 & roller brake nexus 8 hubs?
Or are there any other differences that would render such an adaptation not possible?

Any and all info is very welcome. Thanks.

ps.: before anyone asks, I understand such a conversion is not feasible for most folks..But I work in a machine shop so I can get stuff made.. for free, basically.

Dan Burkhart 

The Di2 has a different axle assembly with no spring return so it can’t be retrofitted with a mechanical shifter. The stepper motor does the work both ways on the Di2 .

veganbikes

Also I don't recall Nexus doing Di2 that would be Alfine but unfortunately as Dan Burkhart said it is not convertible. However roller brakes work well and di2 is awesome so would be a cool bike or if nothing else sell the Di2 stuff and get a new wheel and shifter and assuming your bike has disc brake mounts a disc brake and bingo-bango you have what you want and probably won't cost you much and potentially the sale of the Di2 stuff will more than cover it.

FBinNY 

Maybe the smart play is to shop for the exact hub you want, and sell this one to help pay for it.

grumpus

SG-C6061-8R appears to be a Di2 Nexus for roller brake, exactly as the OP stated. He wrote "I can get" not "I have purchased". There's nothing about a Di2 hub that prevents you from making a mechanical shifter for it, it just has to be able to push and pull, rather than only pulling and relying on a return spring.

Dan Burkhart 

If the indexing was in the hub rather than in the shifter (ie Rohloff), this would be possible, but home brewing a two way shifting apparatus with the precise increments required would be quite an engineering feat.
Note I did not say impossible.

grumpus

I was thinking you could do it with a 3D printer; all you need is a helical ramp with detents, mounted concentric with the axle, a sprung follower and two cables pulling in opposite directions going to a throttle-cable-like shifter. So the indexing would be nearly in the hub.

GamblerGORD53

Forget it. And yah, roller brakes are a boat anchor.

ign1te 

Just buy the hub for learning/spare parts. I do that all the time.

tcs

From my files:

"Cesur rollerbrake to disc adapter"


Now you know as much as I do.