Nexus 8 -Speed Bicycles

Ryan Cousineau

In article <8b4b7de4.0404221228.15b21eeb@posting.google.com>,
chumpychump@hotmail.com (Chalo) wrote:

> Ryan Cousineau <rcousine@sfu.ca> wrote:
>
> > Hey Chalo, you'll like my latest thought-experiment: a hub-geared BMX
> > with a tall seat, flat or drop bars, and high-pressure tires. It will be
> > the world's lousiest folding bike (doesn't fold, y'see), or a great way
> > of gaming airline bike-handling rules.
>
> That's almost the bike I've been building for one of my co-workers.
> He aimed for "world's lightest BMX bike" but eventually came to rest
> on "possibly world's most expensive BMX bike".
>
> It's an aluminum monocoque BMX race frame carefully jacked open and
> milled to accept a SRAM 5-speed hub with drum brake. Both hubs are
> laced to 20" Velocity Deep-Vs with 110psi slicks. Carbon fork,
> aluminum handlebars, Race Face Next LP cranks, Speedplay pedals. Long
> 31.6mm seatpost. Projected complete weight: 20 pounds.

Weird! Wonderful! Any likely bugbears?

Why did you decide on the 5-speed hub, as opposed to the 7? Or, for that
matter the Rohloff, since that would get you closer to your new goal .

I'll probably be starting out with a steel frame from the attic, so I
don't anticipate as many issues with frame spreading and such. I'm not
obsessed about the weight or aerodynamics; I want a bike that is sort of
a fast-as-possible cheap-and-transportable bike, or maybe a death-metal
Moulton. Hm. Since I'm going to an island with a lot of stair steps,
maybe I should get a suspension fork and really go to town.

> The front end of a 20" bike is so short, drop bars would be a sick
> joke. Flat bars or cowhorns would give a time-trial/pursuit kind of
> riding position.

Interesting thoughts. I'm thinking a flat bar (maybe with my bolt-on
aero bars brought along for extra sickness) would be the way to go. I
suppose there's no real reason to not use the stock BMX-style
handlebars, is there? Besides looks?

> Certainly this bike would be mind-bogglingly easier to travel with
> than any of my own bikes.

Seems to me that a BMX or cruiser might work for your travelling needs.
I bet even a Co-Motion-style traveling road/mtb frame would be awfully
big in your sizes. Clearly a case where compact geometry would be
functional .

I hope you'll post pictures of this project when you're done. Sounds
like a case of wretched excess at its finest. This is a really, really
admirable project. I think you should send some shots to a BMX magazine
or two when you've finished. Or maybe just Chunk 666.

--
Ryan Cousineau, rcousine@sfu.ca http://www.sfu.ca/~rcousine/wiredcola/
President, Fabrizio Mazzoleni Fan Club

Alex Rodriguez

In article <8b4b7de4.0404211543.562929db@posting.google.com>,
chumpychump@hotmail.com says...
>
>
>Pete Cresswell wrote:
>>
>> Chalo wrote:
>> >The SRAM/Sachs Spectro 7 is noticeably freer-running. And the middle
>> >gear is direct-drive.
>>
>> Any feeling for how Roloff's hub compares?
>
>It's more like the Sachs than like the Shimano in that regard. Just
>fiddling with the hub in my hands, my impression is that it's got more
>internal drag than the Spectro, but on the street it's very hard to
>tell. The Rohloff makes more noise and thus makes me feel like it's
>draggier, but that could well be a misconception.
>
>The Shimano Nexus 7 is pretty quiet, has a decent brake, shifts
>quickly and reliably, stashes all its shifting hardware inboard of the
>dropouts, and dissipates a lot of energy. I doubt that the Nexus 8 is
>too different, but I've never seen one so I can't say.

The subject line says Nexus 8, but everyone is talking about the Nexus 7.
Has anyone tried the new Nexus 8? It is supposed to be more efficient than
the Nexus 7.
------------
Alex

Chalo

Ryan Cousineau <rcousine@sfu.ca> wrote:
>
> chumpychump@hotmail.com (Chalo) wrote:
> >
> > It's an aluminum monocoque BMX race frame carefully jacked open and
> > milled to accept a SRAM 5-speed hub with drum brake. Both hubs are
> > laced to 20" Velocity Deep-Vs with 110psi slicks. Carbon fork,
> > aluminum handlebars, Race Face Next LP cranks, Speedplay pedals. Long
> > 31.6mm seatpost. Projected complete weight: 20 pounds.
>
> Why did you decide on the 5-speed hub, as opposed to the 7? Or, for that
> matter the Rohloff, since that would get you closer to your new goal .

It looked likelier to be able to spread the stays from 110mm to 126mm
than to 135mm. I was rooting for a coaster brake model which would
have made it 122mm, but my pal liked the idea of a drum. Heck, *I*
like a drum on a 20" wheel!

The machining part of the operation was to remove a wall surrounding
the dropout slot, in order to provide clearance for the shifter
clickbox.

> I want a bike that is sort of
> a fast-as-possible cheap-and-transportable bike, or maybe a death-metal
> Moulton. Hm. Since I'm going to an island with a lot of stair steps,
> maybe I should get a suspension fork and really go to town.

I highly recommend the Primo Comet tire: file treaded, rated at
110psi, and available in 1.35, 1.95, and 2.1 nominal widths. The big
one compensates pretty well for the small wheel diameter.

Suspension fork? Sounds like a request for your nearest bike
recycler. There are not many new 20" suspension forks that outclass
the ones found on the nicer major-brand kid-sized MTBs. AFAIK White
Brothers are the only outfit to offer a sophisticated 20" suspension
fork, which is pricey and not likely to suit your application better
than a steel-tubed spring/elastomer job.

> > The front end of a 20" bike is so short, drop bars would be a sick
> > joke. Flat bars or cowhorns would give a time-trial/pursuit kind of
> > riding position.
>
> Interesting thoughts. I'm thinking a flat bar (maybe with my bolt-on
> aero bars brought along for extra sickness) would be the way to go. I
> suppose there's no real reason to not use the stock BMX-style
> handlebars, is there? Besides looks?

Not really. They are stiffer and stronger than cantilevered bars, but
much heavier. Typically you'll get 7" of rise from BMX bars but none
from the stem, whereas you could use flat bars and MTB stem for less
rise but more reach options.

Chalo Colina