Bicycle Mechanics - Nexus 8 hub dropout spacing? Roller brake?

I'm having difficulty determining this. Shimano's website is less than informative. Harris cyclery is even a bit unclear. Universal cycles has it labelled as 135mm...but is that absolute?

I have a frame with 130mm dropouts that is soon to be rebuilt with a Nexus 8 hub...I hope. If it doesn't fit, I guess it's back to the drawing board.

Also, would someone be so kind as to explain the difference between a roller and a coaster brake?

I have two nexus 8 speed hubs, so There's my qualifications to reply to this thread.

First, roller versus coaster brake.

A coaster brake is a backpedaling brake, which you probably already knew. The roller brake works rather similarly to a drum brake on a car, the primary difference is that the roller brake uses metal-metal contact for stopping instead of a brake pad (Hence why they warn about keeping it greased). The roller brake is actuated like any normal rim brake.

If you use the roller brake on the Nexus hub you're gonna be at 135mm for the width. If you don't you're gonna be closer to 132. (That is, if you use a roller brake compatible hub, with no roller brake.)

That said, Depending on the frame you're using this may or may not be an issue. One of the frames I'm running a Nexus on is an old schwinn suburban (Old 5 speed rear spacing... with the original wheels so I know it wasn't respaced) and the hub required very little coaxing to fit inside.

If it's a steel frame I wouldn't worry either way. If it's aluminum, I would probably leave the roller brake off just to be safe (Honestly it doesn't work that great, the main reason I went with it was to save wear on the rims since I use the bike in muddy conditions.)

Hope this helps.

It should fit. All of the Nexus 8 hubs are 132mm except the coaster brake version which is 132.3mm. Just about any 130mm frame should spread that far.

A coaster brake is activated by backpedaling, a roller brake mounts to the hub like a disc rotor and requires a lever and cable.

Thanks for the clarification.

I wonder why they don't make a disc hub?

Who knows, but if you search a bit, there are disc adapters available.

http://i95.photobucket.com/albums/l156/Wordbiker/Nexusdiscadapter.jpg

Sturmey-Archer does have an 8-speed disc hub, but you would have to add a caliper mount to the frame. Perhaps Shimano doesn't want to be sued over someone mounting a disc hub and caliper on a frame not designed for the additional torsional loads.

The Alfine is an 8 speed Shimano disc hub.

http://bike-components.de/catalog/Alfine+S500+Disc+Center+Lock+HR-Nabe+135+mm?osCsid=492d56d77cc793a22fda481ee0948c8e
http://bike-components.de/catalog/images/products/big/15457.jpg

Nice!

Too bad we may not see that in the States.

I'm having difficulty determining this. Shimano's website is less than informative. Harris cyclery is even a bit unclear. Universal cycles has it labelled as 135mm...but is that absolute?

I have a frame with 130mm dropouts that is soon to be rebuilt with a Nexus 8 hub...I hope. If it doesn't fit, I guess it's back to the drawing board.

Also, would someone be so kind as to explain the difference between a roller and a coaster brake?The Nexus has a nice long threaded axle, and can be used with any spacing between about 126 and 135 or more by adding/removing spacers. The narrower spacings preclude the use of the Rollerbrake. I've got one of mine set at 126, t'other at 130, using rim brakes.

I don't like the Rollerbrake because it's too heavy. I like coaster brakes even less.

When you find a bicycle technical term you don't understand, try: http://sheldonbrown.com/glossary

Sheldon "Neck's Us" Brown

+-------------------------------------------------------------+
| Give a man a fire, and he will stay warm for a day. |
| Set a man on fire, he stays warm for the rest of his life. |
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Nice!

Too bad we may not see that in the States.
You can always order it from the site I posted, they ship world wide.

Good info about the Nexus hub. Thanks everyone.

Numerous people beat me to the "Alfine isn't in the States yet..." comment. I wonder if internal hubs will ever come with a "brifter" style shifter?

...
I don't like the Rollerbrake because it's too heavy. I like coaster brakes even less.

The heck with the weight, I don't like the rollerbrake because it doesn't stop very well.

Rim brakes are a marvel of simplicity and effectiveness. And light weight.