Re: Nexus 8 -Speed Bicycles

Rocketman said:

Just wanted to put in my $.02 about the Shimano Nexus rear hub. I had a
brand new 7-speed Nexus rear hub on my 2003 Van Dessel Super Fly last
season. The rear hub really seemed to be eating quite a lot of pedaling
energy. It always felt like I was pedaling uphill or something.

The SRAM/Sachs Spectro 7 is noticeably freer-running. And the middle
gear is direct-drive.

FWIW, I feel like whatever hypothetical efficiency one gains by using
a derailleur system is as often as not squandered by poor chainline
and draggy bends around the pulleys. (To say nothing of dumping the
chain every so often.)

Chalo Colina

Chalo said:

Rocketman said:

Just wanted to put in my $.02 about the Shimano Nexus rear hub. I
had a brand new 7-speed Nexus rear hub on my 2003 Van Dessel Super
Fly last season. The rear hub really seemed to be eating quite a
lot of pedaling energy. It always felt like I was pedaling uphill
or something.

The SRAM/Sachs Spectro 7 is noticeably freer-running. And the middle
gear is direct-drive.

FWIW, I feel like whatever hypothetical efficiency one gains by using
a derailleur system is as often as not squandered by poor chainline
and draggy bends around the pulleys. (To say nothing of dumping the
chain every so often.)

Efficiencies for various types of drivetrains have been measured and published,
and the derailer setup still comes out on top. Unfortunately, I can't find the
URLs at the moment.

Cross-chained and small-small gear combos are least efficient, worse than some
internal gear hubs'. I was surprised to see how poor a standard MTB drivetrain
performed in certain gear combinations -- less than 90% efficiency. But the
best combinations are right up there at 97-98%, which hub gears can't touch.

Matt O.

"Matt O'Toole" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Efficiencies for various types of drivetrains have been measured and published,
and the derailer setup still comes out on top. Unfortunately, I can't find the
URLs at the moment.

Cross-chained and small-small gear combos are least efficient, worse than some
internal gear hubs'. I was surprised to see how poor a standard MTB drivetrain
performed in certain gear combinations -- less than 90% efficiency. But the
best combinations are right up there at 97-98%, which hub gears can't touch.

Perhaps this one?
http://www.ihpva.org/pubs/HP52.pdf

[email hidden] (papercut) wrote in message news:<[email hidden]>...

Quoted message said:

"Matt O'Toole" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Efficiencies for various types of drivetrains have been measured and published,
and the derailer setup still comes out on top. Unfortunately, I can't find the
URLs at the moment.

Cross-chained and small-small gear combos are least efficient, worse than some
internal gear hubs'. I was surprised to see how poor a standard MTB drivetrain
performed in certain gear combinations -- less than 90% efficiency. But the
best combinations are right up there at 97-98%, which hub gears can't touch.

Perhaps this one?
http://www.ihpva.org/pubs/HP52.pdf

There's also a follow-up to that article in Human Power #55, comparing
derailleur systems and the Rohloff hub. Recommended reading for anyone
wanting to *really* measure drivetrain efficiencies.

Jeff

RE/

Quoted message said:

The SRAM/Sachs Spectro 7 is noticeably freer-running. And the middle
gear is direct-drive.

Any feeling for how Roloff's hub compares?
--
PeteCresswell

Thanks everyone, I'm going to keep looking. The Cannondale Street Roloff
looks great too.

"(Pete Cresswell)" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

RE/

Quoted message said:

The SRAM/Sachs Spectro 7 is noticeably freer-running. And the middle
gear is direct-drive.

Any feeling for how Roloff's hub compares?
--
PeteCresswell

RE/

Quoted message said:

Thanks everyone, I'm going to keep looking. The Cannondale Street Roloff
looks great too.

Just be aware that there's nothing about the Rohloff hub that limits it to being
used on any particular make/model of bike except for the axle width (135mm MTB
standard...).

I've got one on my hardtail, one on my Ellsworth Isis FS...and used to have one
on my Cannondale Jekyll when I had it.
--
PeteCresswell

Pete Cresswell said:

Chalo said:

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.

Chalo Colina

(Pete Cresswell) said:

Just be aware that there's nothing about the Rohloff hub that limits it to being
used on any particular make/model of bike except for the axle width (135mm MTB
standard...).

Well, yes...but chain tensioners-- even Rohloff's-- are cheesy. The
hub is a better match for horizontal or adjustable dropouts, or an
eccentric BB. That really cuts down on the selection of frames.

I mean, why use a gearhub in a system that can dump the chain just
like a derailleur bike?

Chalo Colina

In article <[email hidden]>,

(Chalo) said:

(Pete Cresswell) said:

Just be aware that there's nothing about the Rohloff hub that limits it to
being
used on any particular make/model of bike except for the axle width (135mm
MTB
standard...).

Well, yes...but chain tensioners-- even Rohloff's-- are cheesy. The
hub is a better match for horizontal or adjustable dropouts, or an
eccentric BB. That really cuts down on the selection of frames.

I mean, why use a gearhub in a system that can dump the chain just
like a derailleur bike?

Chalo Colina

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.

Thinking, thinking...
--
Ryan Cousineau, [email hidden] http://www.sfu.ca/~rcousine/wiredcola/
President, Fabrizio Mazzoleni Fan Club

Ryan Cousineau said:

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.

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.

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

Chalo Colina

RE/

Quoted message said:

I mean, why use a gearhub in a system that can dump the chain just
like a derailleur bike?

My FS dumped the chain a few times, but that was a good year ago before I put a
bash ring where the outside ring would go. No dumps since.
--
PeteCresswell

In article <[email hidden]>,

(Chalo) said:

Ryan Cousineau said:

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.

Quoted message said:

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?

Quoted message said:

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, [email hidden] http://www.sfu.ca/~rcousine/wiredcola/
President, Fabrizio Mazzoleni Fan Club

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Pete Cresswell said:

Chalo said:

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

Ryan Cousineau said:

(Chalo) said:

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.

Quoted message said:

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.

Quoted message said:

Quoted message said:

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

Alex Rodriguez said:

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.

Well, Biopace was supposed to be more efficient than round rings....

The Nexus 8 actually has a direct-drive gear, right above the middle
of the range where it could prove very useful. Even if the gears and
bearings are what we have come to expect from Shimano Nexus equipment,
that one change could be of benefit.

Chalo Colina