Shimano Nexus 8-speed Hubs

[Sheldon Brown]

It's been over a year since we first placed our order, but we finally
have received Shimano Nexus 8-speed hubs.

I bought one myself, I'll be doing it up with 650B rims...

See: http://harriscyclery.com/shimano-nexus

I've also scanned and put up the Service Manual for these hubs at:

http://sheldonbrown.com/nexus8

Sheldon "Planetary Gears!" Brown
+----------------------------------------------+
| If you wish in the world to advance, |
| Your merits you're bound to enhance; |
| You must stir it, and stump it, |
| And blow your own trumpet, |
| Or, trust me, you haven't a chance! |
| --W.S. Gilbert |
+----------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Jose Rizal]

Sheldon Brown:

> It's been over a year since we first placed our order, but we finally
> have received Shimano Nexus 8-speed hubs.
>
> I bought one myself, I'll be doing it up with 650B rims...
>
> See: http://harriscyclery.com/shimano-nexus
>
> I've also scanned and put up the Service Manual for these hubs at:
>
> http://sheldonbrown.com/nexus8

Looks nice, but what's the principle of the roller brake, and what is
the disk with what looks like guide vanes on the brake side of the hub?

 

[[email protected]]

Jose Rizal wrote:
>
> Looks nice, but what's the principle of the roller brake, and what is
> the disk with what looks like guide vanes on the brake side of the
hub?

Here you go:
http://www.shimano-europe.com/cycling/catalogue/content_prodx.phtml?pid=11081&psid=10523

The disk is a heat sink for the brake. The principle behind a roller
brake is similar to a drum brake, the difference being that instead of
organic material, steel rollers are pressed outward into a metal drum.
I can't tell you what the advantage this would have.

Jeff

 

[Tom Ace]

Sheldon Brown wrote:

> See: http://harriscyclery.com/shimano-nexus
>
> I've also scanned and put up the Service Manual for these hubs at:
>
> http://sheldonbrown.com/nexus8

Thanks Sheldon for the info.

Do you know how many planetary stages the hub has,
and what combinations of stages are used in each gear?

Shimano says it has a silent clutch; is there no pawl
click when coasting?

Just curious.

Tom Ace

 

[Sheldon Brown]

I wrote:

>>See: http://harriscyclery.com/shimano-nexus
>>
>>I've also scanned and put up the Service Manual for these hubs at:
>>
>>http://sheldonbrown.com/nexus8

Tom Ace asked:

> Do you know how many planetary stages the hub has,
> and what combinations of stages are used in each gear?

Nope.

> Shimano says it has a silent clutch; is there no pawl
> click when coasting?

I presume not, that's what "Silent Clutch" mean, but I'm still waiting
for rims to build up my own.

Sheldon "Gonna Try 650B" Brown
+----------------------------------------+
| All theory, dear friend, is grey, |
| but the golden tree of actual life |
| springs ever green. --Goethe |
+----------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Jim Smith]

Sheldon Brown <[email protected]> writes:

> It's been over a year since we first placed our order, but we finally
> have received Shimano Nexus 8-speed hubs.
>
> I bought one myself, I'll be doing it up with 650B rims...
>
> See: http://harriscyclery.com/shimano-nexus
>
> I've also scanned and put up the Service Manual for these hubs at:
>
> http://sheldonbrown.com/nexus8
>

Do they make them without the brake?

 

[hhu]

Thanks for posting the stuff on these hubs.

I am still curious about exactly what the "roller" brake. The
exploded view doesn't show or list any pads. How does this thing
work, and is it good in wet conditions?

If one were to ignore the increased width, how hard would it be to fit
a cassette to one of these hubs? I know it sounds silly, but us DIY
recumbent people are always looking for new ways to handle gearing.

Thanks

 

[Tom Sherman]

hhu wrote:

> ...
> If one were to ignore the increased width, how hard would it be to fit
> a cassette to one of these hubs? I know it sounds silly, but us DIY
> recumbent people are always looking for new ways to handle gearing.

Now I want a 10-speed cassette on a Rohloff hub, and a quadruple crank
on a Schlumpf bottom bracket.

--
Tom Sherman - Earth

 

[Tom Sherman]

Sheldon Brown wrote:

> It's been over a year since we first placed our order, but we finally
> have received Shimano Nexus 8-speed hubs.
>
> I bought one myself, I'll be doing it up with 650B rims...

Say it ain't so Joe (er, Sheldon)!

--
Tom Sherman - Earth

 

[Chalo]

Sheldon Brown wrote:
>
> It's been over a year since we first placed our order, but we finally

> have received Shimano Nexus 8-speed hubs.
>
> See: http://harriscyclery.com/shimano-nexus

Confound it. True to clueless form, Shimano have dished up a heaping
helping of asymmetrical flange offset on a hub that didn't need to have
any.

Another nugget on the towering mountain of reasons not to buy their
****-- like I really needed another one.

Chalo Colina

 

[Sheldon Brown]

Chalo wrote:

> Confound it. True to clueless form, Shimano have dished up a heaping
> helping of asymmetrical flange offset on a hub that didn't need to have
> any.

2.7 mm is a "heaping helping" of asymmetry? Most non-flip-flop hubs
have at least this much asymmetry.

See: http://sheldonbrown.com/nexus8/pages/28.htm

Even typical track hubs are more asymmetrical than this, viz:

Campagnolo 5-13 depending on model,
Miche at 15,
Phil Wood at 14 mm,
Sun Tour at 6 mm.

See: http://sheldonbrown.com/spocalc.

> Another nugget on the towering mountain of reasons not to buy their
> ****-- like I really needed another one.

"****?" This is the best multi-speed hub you can buy for less than
$700! Sounds like predjudice to me.

Sheldon "Millions Of People Say _I_ Exaggerate!" Brown
+--------------------------------------------------+
| Pohl's law: Nothing is so good that somebody, |
| somewhere, will not hate it. |
+--------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[[email protected]]

hhu wrote:
> Thanks for posting the stuff on these hubs.
>
> I am still curious about exactly what the "roller" brake. The
> exploded view doesn't show or list any pads. How does this thing
> work, and is it good in wet conditions?
>

It's kind of similar to a coaster brake, in that braking is
accomplished by metal-to-metal contact. They need to be kept greased,
otherwise BAD THINGS begin to happen.

I would expect it to be as good in the wet as it is in the dry, up to
the limit of the tire's adhesion. I don't have direct experience with
the roller brake to say anything beyond that.

Jeff

 

[Tom Sherman]

Sheldon Brown wrote:

> ...
> "****?" This [Nexus-8] is the best multi-speed hub you can buy for less than
> $700!...

I wish someone would test the efficiency of the Nexus-8 versus the
Spectro-7.

I wonder if SRAM will respond with a "Spectro-8" or "Spectro-9"?

--
Tom Sherman - Earth

 

[[email protected]]

Jim Smith wrote:
> > http://sheldonbrown.com/nexus8
> >
> Do they make them without the brake?

Yes. The brake is not an integral part of the hub.
http://www.shimano-europe.com/cycling/catalogue/content_prodx.phtml?pid=11455&psid=11453
Jeff

 

[Sheldon Brown]

hhu wrote:

> Thanks for posting the stuff on these hubs.
>
> I am still curious about exactly what the "roller" brake. The
> exploded view doesn't show or list any pads. How does this thing
> work, and is it good in wet conditions?

It's a drum brake, but instead of pushing the shoes apart at one place,
180 degrees from the hinge, there are 6 rollers surrounding a hexagonal
cam. The brake arm turns this cam, pressing the 6 rollers against the
inner circumference of the brake shoe. This produces a more even
pressure around the shoe/drum than a typical drum brake.

Like any hub brake, it works as well in wet conditions as it does in dry
conditions.

I test rode a bike with one of these hubs on a longish steep mountainous
descent out in Nevada a year ago. I tried keeping my speed in check
using only the Roller Brake, and found that it suffered from pretty bad
fade under those extreme conditions. I was very glad the bike had a
V-Brake in front.

I probably won't install the roller brake on my own hub, It's pretty
heavy and I only very rarely use a rear brake in any case. I'm
tentatively planning to use Weinmann centerpulls front and rear.

> If one were to ignore the increased width, how hard would it be to fit
> a cassette to one of these hubs?

No way, the shift cable linkage wouldn't clear.

> I know it sounds silly, but us DIY
> recumbent people are always looking for new ways to handle gearing.

http://sheldonbrown.org/otb.html 63 speeds.

I am toying with the idea of running a double or triple chainring with
this hub. Still need a rear derailer to take up the slack though.

Sheldon "Epicyclic" Brown
+-------------------------------------------------------+
| Do what you can, with what you have, where you are. |
| --Theodore Roosevelt |
+-------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Sheldon Brown]

I wrote:
>
>>It's been over a year since we first placed our order, but we finally
>>have received Shimano Nexus 8-speed hubs.
>>
>>I bought one myself, I'll be doing it up with 650B rims...
>>
>>See: http://harriscyclery.com/shimano-nexus
>>
>>I've also scanned and put up the Service Manual for these hubs at:
>>
>>http://sheldonbrown.com/nexus8
>>
Jim Smith asked:
>
> Do they make them without the brake?

You can leave the brake off. That's what I did with my Nexus 7-speed.

http://sheldonbrown.org/raleigh-competition

If you don't want the brake, we'll knock 15 bucks off the price.

I haven't yet decided whether I'll go with the brake on my new 8-speed.

Sheldon "Neck's Us" Brown
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Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Ryan Cousineau]

In article <[email protected]>,
Sheldon Brown <[email protected]> wrote:

> It's been over a year since we first placed our order, but we finally
> have received Shimano Nexus 8-speed hubs.
>
> I bought one myself, I'll be doing it up with 650B rims...

Okay, I've read the Rivendell ode to this rim size, but aside from
acting as some sort of revivalist preservation of the rim and tire
standards so future generations can roll along on mid-century French
bicycles, the attraction is purely aesthetic, right?

Or is there some advantage to spanning the 559-622 mm interval I haven't
perceived? Maybe a compromise for 29er-like off road virtues but with
stronger wheels?

"ISO 584?"
--
Ryan Cousineau, [email protected] http://www.wiredcola.com
Verus de parvis; verus de magnis.

 

[A Muzi]

> Sheldon Brown <[email protected]> writes:
>>It's been over a year since we first placed our order, but we finally
>>have received Shimano Nexus 8-speed hubs.
>>I bought one myself, I'll be doing it up with 650B rims...
>>See: http://harriscyclery.com/shimano-nexus
>>I've also scanned and put up the Service Manual for these hubs at:
>>http://sheldonbrown.com/nexus8

Jim Smith wrote:
> Do they make them without the brake?

SG-8R25, SG-8R20 are 8 speed hubs which can accept a roller
brake.
SG-8R25-VS, SG-8R20-VS are the eight hubs which cannot ("VS"
for "use a V-Brake")

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[Pete Biggs]

Besides the extra gear, and the silent clutch, are there any differences
in terms of perfomance, durabilty and weight between it and the Nexus 7
hub?

thanks
~PB

 

[Zach]

Sheldon:

I am curious why you are going to lace the Nexus hub to a 650B rim.
Isn't that an archaic size? Why not use the common 559mm instead?
Zach Kaplan