internal hub gearing for mtb

[Pete Biggs]

ouch wrote:
> Is a roller brake similar to a drum brake?

I think so (same thing?). I don't know much about drum brakes but know the Nexus I've tried has a
"roller brake" - which is a cable operated hub brake. It works reasonably well although is not
tremendously powerful - but does work better than rim brakes in the rain. This is another feature to
cut down on regular maintenance as well. No rear brake blocks to align, change, make rim & tyre
dirty, rub out-of-true rim, etc.

~PB

 

[Pete Biggs]

Pete Biggs wrote:

>> Is a roller brake similar to a drum brake?
>
> I think so (same thing?).

Sorry, after Chris's post, I realise it isn't!

~PB

 

[Pete Biggs]

chris French wrote:

> The Nexus hubs don't come with a roller brake built in, even if you by them together. It just fits
> onto the left hand side of the hub.

I've grabbed a Shimano brochure now..... There seems to be two main versions: SG-7R45 which can be
used with a roller brake (and I would expect some to come pre-assembled with one), and the SG-7C25
which features a coaster brake (back pedal to brake, no cable), alloy shell, and also a Roller
Clutch to provide quick engagement and silent freewheeling.

~PB

 

[Ouch]

>TBh, I'm not entirely sure how my roller brake works.......... I did Google it once but never got
>anything much, other than it has roller applied by a cam. However, you are supposed to apply a
>special grease into them every year or so.
>
>In contrast, my Sachs hub brake has brake shoes which are applied by a cam in much the same way as
>drum brakes on a car or motorbike.
>
>As you mentioned lack of maintenance is one of the great things about these brakes. Bar the
>occasional cable adjustment, and the very occasional lubrication of the cam and the odd replaced
>cable I've had to do nothing to my drum brake. It just sits there and works, year after year, sun,
>rain or snow.

How would you rate their performance? I've read once that first generation mtbs used to be fitted
with drum brakes that had to be readjusted (or something) before every DH because they heated up so
much. On that note I'd hope that roller brakes are much better.

I'm not too "fashion conscious" in that I've never seen any real need to change to disc brakes. The
limiting factor for me hasn't been brake performance but tyre grip with respect to the surface. The
only situation I would prefer to have discs is in very muddy conditions where rim brakes would
become clogged.

 

[Tony W]

snip

> Thanks for that. I was also a bit wary of SA since they were taken over by the Taiwanese company a
> few years ago. I don't know what their quality is like.

Sheldon Brown suggests (sorry, can't quickly locate the link) that quality has improved markedly
since the take over. Probably not difficult.

> Since Rohloff is German the quality, durability etc should be pretty good.

Quality & durability are functions of the design and quality of manufacturing -- not of the location
or ownership of the factory.

> The 27sp equivalent should also suit my application a lot better.

Lots of overlap on a 27 gear derailleur.

T

 

[Tony W]

<ouch> wrote in message news:[email protected]...

>
> Do you know whether the Nexus is any good? I can't find any reviews. I think I could cope with a 7
> speed (I'll just have to strengthen these spindly legs).

SRAM also do hub gears

 

[Peter Clinch]

Tony W wrote:

> SRAM also do hub gears

As do Sturmey/Sunrace. They're just in the process of launching an 8 speed IIRC.

Pete.
--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email protected]
http://www.dundee.ac.uk/~pjclinch/

 

[Peter Clinch]

Pete Biggs wrote:

> Not necessarily. Both systems can shift very well when properly setup.

Though this is very true, it is sadly the case that an MTB with a derailleur covered in a very
large quantity of cack, even if only temporarily, cannot be considered "properly setup" for the
next shift :-(

> 5. More weight (for any affordable hub gear system)

More weight for the unaffordable one too, so even if you're rich it isn't a perfect solution :-(

Pete.
--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email protected]
http://www.dundee.ac.uk/~pjclinch/

 

[Pete Biggs]

kit wrote:
> On the downside, a single rear sprocket takes all the wear and tear and so will presumably wear
> out faster than a cassette would - unless it's made of stronger metal to compensate.

Sprocket wear is mainly caused by chain wear (elongation) and I would expect the type of chain used
with these systems to last longer as it's that much chunkier and is used at a consistently good
angle (single chainline instead of crossed-over gears). Also, typical single sprockets are larger
than the cassette sprockets that tend to wear most (smaller sprockets wear faster than large).

~PB

 

[Ouch]

>> The 27sp equivalent should also suit my application a lot better.
>
>Lots of overlap on a 27 gear derailleur.
>
>T

I agree and have to confess that I don't use all of my 27 gears on my current mountainbike. My main
problem is on the climbs, especially off road. If I change into a low gear too early (for example
the granny ring and one of the larger plates on the back) I can't shift back. Then if I come off
while going uphill I can't get restarted without shifting into a higher gear, which isn't possible,
etc. So for that reason alone if internal gears perform as they say they do, I would hope to be able
to use any and all the gears at any time. It would make a great difference to my riding.

And of course a 27sp has more va-va-voom than anything else. ;-)

P.S. Though I'm sure my technique could do with honing too

 

[Alex Graham]

Simon Brooke wrote:

> Frankly, would you _want_ them to have the same internals? I don't know about you but I grew up
> with Sturmeys and I hate them with a passion. Truly **** British engineering at it's worst. Balky,
> unreliable, and with very unsafe modes of failure.
>
> The Taiwanese ones have _got_ to be better.

You what? The three speed AW is an excellent hub - pretty reliable - just think how many bikes in
daily use at the moment have them!

Admittedly some of the other variations were a bit evil, like the SW (I think).

--

-Alex

----------------------------------
[email protected]

http://alexpg.ath.cx:3353/cycling.php http://www.westerleycycling.org.uk
----------------------------------

 

[Peter Clinch]

ouch wrote:

> I agree and have to confess that I don't use all of my 27 gears on my current mountainbike.

Nobody really uses all 27 on a 27, unless they're a bit mad: given the amount of overlap, if you use
small chainwheel with small rear cogs (or big and big) then you're just adding to chain and sprocket
wear by having the chain at a pronounced angle for no gain, so Not A Cunning Plan.

On my 3x9 on the touring 'bent, I reckon a chainring change is a shade more than 2 notches at the
back, which makes sense when you think the Rohloff's 14 speeds are roughly equal in total range and
step to a 3x9.

> road. If I change into a low gear too early (for example the granny ring and one of the larger
> plates on the back) I can't shift back.

Sounds like you need to fiddle with the adjustment a bit. The only time a derailleur should give
problems is if you're really mashing a gear so there's *lots* of tension on the chain when you try
and shift. But if you're in too low a gear too early then your feet should be windmilling at
enormous speed, and a subsequent shift shouldn't have too much load on the chain.

> Then if I come off while going uphill I can't get restarted without shifting into a higher gear,
> which isn't possible, etc.

It's a pain in the ****, and part of why I prefer hubs for general use, but you can always pick up
the back and spin the pedals to get the chain over before you try and restart.

> P.S. Though I'm sure my technique could do with honing too

Another nice thing about a hub is there's very little adjustment ever needing done to keep the
changes true, but it's not *that* hard on a derailleur, and if you keep it true then it makes a big
difference to ride quality.

Pete.
--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email protected]
http://www.dundee.ac.uk/~pjclinch/

 

[Chris French]

In message <[email protected]>, Pete Biggs
<pbiggmellon{remove_fruit}[email protected]> writes
>kit wrote:
>> On the downside, a single rear sprocket takes all the wear and tear and so will presumably wear
>> out faster than a cassette would - unless it's made of stronger metal to compensate.
>
>Sprocket wear is mainly caused by chain wear (elongation) and I would expect the type of chain used
>with these systems to last longer as it's that much chunkier and is used at a consistently good
>angle (single chainline instead of crossed-over gears). Also, typical single sprockets are larger
>than the cassette sprockets that tend to wear most (smaller sprockets wear faster than large).
>

for whatever reasons, wear has not been an issue with the rear sprocket on my Sachs Super 7, after
maybe 8-10 years use it shows no significant wear.
--
Chris French, Leeds

 

[Simon Brooke]

ouch <> writes:

> Just seen the pics and the details. I'm gobsmacked. Very nice! The Rohloff is out of reach of mud,
> dirt etc too. I wouldn't want to leave it parked in any street though.
>
> >If they could only get the weight and price down people would be queuing up to buy them me
> >included.
>
> How much are they (the Nucleons)?

Yes, I looked too. Amazing looking frames. Amazing looking prices. Nucleon FR 2004 (including
Rohloff) 3599 euros; Nucleon ST 2004 (including Rohloff) 3899 euros. Couldn't find any weights
quoted, but they're all described as 'downhill', 'freeride' or 'enduro'. 'Downhill' and 'freeride'
spell 'heavy' in my prejudiced mind. And a complete bike is going to cost upsides of £3,000. But
they do look interesting.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

'You cannot put "The Internet" into the Recycle Bin.'

 

[Pete Biggs]

Alex Graham wrote:
> Simon Brooke wrote:
>
>> Frankly, would you _want_ them to have the same internals? I don't know about you but I grew up
>> with Sturmeys and I hate them with a passion. Truly **** British engineering at it's worst.
>> Balky, unreliable, and with very unsafe modes of failure.
>>
>> The Taiwanese ones have _got_ to be better.
>
> You what? The three speed AW is an excellent hub - pretty reliable - just think how many bikes in
> daily use at the moment have them!

I agree with Simon. In my experience, they often don't stay adjusted properly for long, are
difficult/impossible to repair by the average owner and are extremely dangerous when drive suddenly
completely disappears with no warning whatsoever - far worse than when a chain comes off from a
derailleur system. The fact that they are still widely used in developing countries does not justify
this terrible design.

~PB

"The drive is transmitted from the sprocket through a four slot cup through which a small cross
protrudes to either drive the ring gear by lifting ratchet pawls (low the gear that does not
click when running), performing the same operation with the pawls engaged (direct drive), or
fully extended against the four pins on which the planets ride to drive the planets, hence the
reciprocal relationship between low and high to direct drive down 1/3 up 1/4 on the AW.

"The four pins are free fit in the housing and when loaded are slightly non perpendicular to the
hub axis due to canting within the clearance. This in itself has a disengaging bias to the
driver cross that pushes on them. However, under load, the axle and mechanism bends slightly so
that depth of engagement of the driver cross to the pins varies during each rotation. These two
effects disengage the driver from the pins under high torque and drop the mechanism into free
wheeling forward. The result is that the rider, if standing, dives over the bars, the bicycle
following behind him.

"This condition is apparent upon examining the driver and pins that both become worn in a slant
that enhances disengagement, however, replacing these parts does not resolve the condition. SA
says that the shift cable was mis-adjusted, a specious dodge if ever there was one [although a
mis-adjusted cable (in between gears) can also cause the symptoms, but see last paragraph below
for an answer to that. ~PB]. With the cable disconnected, the driver cross is free to make
perfect contact with the face of the planet carrier, the best adjustment possible for top gear,
and still disengage under load.

"Had the driver been sloped and pins been made with matching flared tapered ends, this would not
have been an issue although misadjustment could still leave one teetering at the edge of
freewheeling forward."

"....Anything that goes wrong with an SA hub has, over the years been thoroughly thrown back at
the user as misuse. The customer is always wrong. As I pointed out, a device that regularly
fails in the hands of the user is a failure in design, regardless of whether the human is not
using it as the designer imagined. That is part of the design effort."

- Jobst Brandt, rec.bicycles.tech, 2000/04/01

 

[Ouch]

<snip snip>

>Sounds like you need to fiddle with the adjustment a bit. The only time a derailleur should give
>problems is if you're really mashing a gear so there's *lots* of tension on the chain when you try
>and shift. But if you're in too low a gear too early then your feet should be windmilling at
>enormous speed, and a subsequent shift shouldn't have too much load on the chain.

Fiddling with my derailleurs never seems to get me very far. They always work when I'm testing them
while they're "unloaded" but as soon as I'm climbing I tend to get problems. It's also the sort of
thing where if you make one change to fix a problem, another one seems to arise.

>It's a pain in the ****, and part of why I prefer hubs for general use, but you can always pick up
>the back and spin the pedals to get the chain over before you try and restart.

That is a royal pain. I hate having to get off to do that.

If hubs cure that problem then the Rohloff definitely sounds the knees to me. Expensive yes but if
you buy say an XTR chainset and cassette you're already talking £350 anyway so for a bit of
exclusivity,"triumph of teutonic technology" as Mr Sheldon Brown says
+ the advantages mentioned, maybe it's worth it.

I wish I'd asked earlier and maybe I would have looked out for Rohloffs at the Cycle Show.

Thanks Peter

 

[David Nutter]

Peter Clinch <[email protected]> said:

> That's typically the case, though you could run a more limited hub than a Rohloff in conjunction
> with multiple chainwheels to get a bigger range. But ISTM this rather misses points 1-3 above to
> some extent.

Howabout a 7 speed hub and one of those Mountain Drive things? I have no if they're any good, but
the idea of a planetary gear inside the chainset seems quite nifty to me.

http://www.kinetics.org.uk/html/mountain_drive.html

At about 350 quid for the hub and drive, it's not much cheaper than the Rohloff unfortunately.

Regards,

-david

 

[Dave Larrington]

ouch wrote:
>Since Rohloff is German the quality, durability etc should be pretty good. The 27sp equivalent
>should also suit my application a lot better.

A friend has one on his MTB. Early models suffered somewhat from duff oil seals causing them to leak
like old Triumphs. Rohloff advised him to send the complete wheel back to the factory. Resigning
himself to several MTB-less weeks, he posted the thing off to Kassel on a Monday. Complete wheel,
with new hub, returned on Friday.

The problem with the seals has, I believe, now been fixed. One day, when I am rich and famous, I
shall have one.

Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/
===========================================================
Editor - British Human Power Club Newsletter
http://www.bhpc.org.uk/
===========================================================

 

[Alan Braggins]

In article <[email protected]>, Peter B wrote:
>
><ouch> wrote in message news:[email protected]...
>> I'm wondering if anyone has experience mounting an internal hub gear (Sturmey Archer-ish) onto a
>> mountainbike?
>
>This months MBR mag features a Nicolai Nucleon mtb with a Rohloff hub gear system. It's not
>actually built into the rear wheel but close to the swing-arm pivot and proves the point that it's
>fit for the purpose of mtb gearing. I would have thought that notwithstanding the fewer gears
>available a hub mech would be far better suited to winter mtbing, assuming it's well sealed.

GT have something similar with a Shimano hub.
http://www.bikemagic.co.uk/news/article.asp?UAN=3491&SP=&v=1

 

[Peter Clinch]

David Nutter wrote:

> Howabout a 7 speed hub and one of those Mountain Drive things? I have no if they're any good, but
> the idea of a planetary gear inside the chainset seems quite nifty to me.

They do work quite nicely in my limited experience, but forget about fitting it yourself unless you
*really* know what you're doing, and the change is a heel button. That's quite all right when you
see a big climb looming ahead on the road but might need a bit more dexterity than is typically
available in a tight spot on technical trails, at least before a fair deal of practice!

My experience of both Rohloff and Schlumpf is on the same bike! Darth Ben's "Ultimate Commuter",
at Kinetics.

Pete.
--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email protected]
http://www.dundee.ac.uk/~pjclinch/