Hub gears on a horiz-dropout frame?

[Duncan Smith]

Not knowing much about hub gears.. is this a feasible idea?

My fixed frame (Pompino) has horizontal drop-outs (no in-bred sliding
drop-outs or gear hangers). On some mornings if I've got to carry a
lot to stuff in the panniers my knees feel like they could make use of
some gears now and again. Or sometimes I just get bored with fixed
and fancy a change..

Would a hub gear like a Rolhoff, Nexus or SA i(f they're still going)
be suitable for a frame with horiz-dropouts? And if I wanted to run
fixed a few days a week and geared for other days, would the linkage
from the hub to the controls be easily removable so I could just
change the wheel over?

This site mentions a chain-tensioner, I thought the whole point of a
hub gear was the chain length/line remains constant but the internal
planetry gears drive the hub at a different rate to the chain

http://www.kinetics.org.uk/html/rohloff1.shtml

After how many miles will a hub gear require servicing, and how much
would it cost (to service)?

Many thanks,

Duncan

 

[Peter Clinch]

Duncan Smith wrote:
> Not knowing much about hub gears.. is this a feasible idea?

Probably.

> Would a hub gear like a Rolhoff, Nexus or SA i(f they're still going)
> be suitable for a frame with horiz-dropouts? And if I wanted to run
> fixed a few days a week and geared for other days, would the linkage
> from the hub to the controls be easily removable so I could just
> change the wheel over?

If you set up a suitable linkage with a cable splitter, I'd guess
probably yes (SA are going strong since they were taken over by Sunrace
in the wake of the asset-strip that brought them down, and SRAM make
gear hubs too).

> This site mentions a chain-tensioner, I thought the whole point of a
> hub gear was the chain length/line remains constant but the internal
> planetry gears drive the hub at a different rate to the chain

it's potentially part of the point. But if, for example, you have a
non-unified rear suspension it's impossible to keep it constant, so
you'll need a tensioner. A Brompton uses a tensioner to stop the chain
falling off when folding is another use.
But while no tensioner is a nice thing, having one doesn't remove the
other advantages like your gears being cack-proof, and the chain line
not being laterally warped any time one changes gear.

> After how many miles will a hub gear require servicing, and how much
> would it cost (to service)?

Don't know. In the 5 or so years I've had my Brom I've done, errrrr,
zero minutes maintenance of the hub and it still seems to work okay.
Rohloffs have huge distances quoted on them with nothing but an oil
change once in a while.

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

 

[bookieb]

On Nov 6, 11:36 am, Duncan Smith <[email protected]> wrote:
> Not knowing much about hub gears.. is this a feasible idea?
>
> My fixed frame (Pompino) has horizontal drop-outs (no in-bred sliding
> drop-outs or gear hangers). On some mornings if I've got to carry a
> lot to stuff in the panniers my knees feel like they could make use of
> some gears now and again. Or sometimes I just get bored with fixed
> and fancy a change..
>
> Would a hub gear like a Rolhoff, Nexus or SA i(f they're still going)
> be suitable for a frame with horiz-dropouts? And if I wanted to run
> fixed a few days a week and geared for other days, would the linkage
> from the hub to the controls be easily removable so I could just
> change the wheel over?
>
> This site mentions a chain-tensioner, I thought the whole point of a
> hub gear was the chain length/line remains constant but the internal
> planetry gears drive the hub at a different rate to the chain
>
> http://www.kinetics.org.uk/html/rohloff1.shtml
>
> After how many miles will a hub gear require servicing, and how much
> would it cost (to service)?
>
> Many thanks,
>
> Duncan

To completely avoid answering any of your questions about hub gears
(sorry!), an alternative, used by some fixie riders is to get a rear
hub which is threaded on both sides - many track/fixie hubs are made
this way.

On one side, they use a track cog and lockring.

On the other, a single speed freewheel, often a couple of teeth
smaller than the fixed cog.

Normally, they ride the fixed track cog as before.

On wet/windy/heavy luggage/tired/"just feel like a change" days, they
can reverse the same wheel, and ride the single speed freewheel side.
Both gears are carried all the time, so you can change while out on
the road.

The chain length has to be carefully set so that it works with both
cogs of different sizes, but with horizontal dropouts of a decent
length, it's normally do-able.

This gives them a "get you home" bail-out gear, not fixed and somewhat
lower than fixed side, without the expense of the second wheel.

Just a suggestion...

regards,

bookieb.

 

[Pete Biggs]

Duncan Smith wrote:
> Not knowing much about hub gears.. is this a feasible idea?
>
> My fixed frame (Pompino) has horizontal drop-outs (no in-bred sliding
> drop-outs or gear hangers). On some mornings if I've got to carry a
> lot to stuff in the panniers my knees feel like they could make use of
> some gears now and again. Or sometimes I just get bored with fixed
> and fancy a change..
>
> Would a hub gear like a Rolhoff, Nexus or SA i(f they're still going)
> be suitable for a frame with horiz-dropouts?

Yes it's *normal* to use hub gears with horizontal dropouts.

> And if I wanted to run
> fixed a few days a week and geared for other days, would the linkage
> from the hub to the controls be easily removable so I could just
> change the wheel over?

It's fiddly with Shimano Nexus hubs. I'm not sure about other modern ones.

> This site mentions a chain-tensioner, I thought the whole point of a
> hub gear was the chain length/line remains constant but the internal
> planetry gears drive the hub at a different rate to the chain

The chain length remains constant but needs to be exactly right (within a
few mm) for tension to be acceptable. Chain length can only be altered in
units of a pair of links (1 inch), so you need some method of fine tuning.
This can be either with some device or by sliding the wheel back and forth
in horizontal droputs until chain tension feels correct.

You need some slack to get the wheel in the dropouts anyway.

> http://www.kinetics.org.uk/html/rohloff1.shtml
>
> After how many miles will a hub gear require servicing, and how much
> would it cost (to service)?

Depends on hub.

See comments on Nexus hubs in another recent thread. Note that these
require 130mm dropouts.

~PB

 

[Pete Biggs]

ps.

An under-tensioned chain may come off or just not work properly.

An over-tensioned chain will cause excessive friction, drag and wear, and
will feel nasty.

~PB

 

[Pete Biggs]

pps. Duncan, you should already know all this from your experience with
your fixie. As far as chain length and tension goes, the same things apply
with hub gears as they do with fixed ones.

So, sorry if I typed far more than necessary!

~PB

 

[Duncan Smith]

On Nov 6, 12:21 pm, "Pete Biggs"
<[email protected]> wrote:
> pps. Duncan, you should already know all this from your experience with
> your fixie. As far as chain length and tension goes, the same things apply
> with hub gears as they do with fixed ones.
>
> So, sorry if I typed far more than necessary!
>
> ~PB

Cool, that's what I'd thought, but the tensioner picture made me doubt
myself. So, I can run without the tensioner treating the bike pretty
much like a normal fixie. And If can disconnect the cable reasonably
easy and tie-wrap it around a chainstay or something - then swapping
between the two should be a quick night-before job.

Many thanks,

Duncan

 

[Duncan Smith]

>
> This gives them a "get you home" bail-out gear, not fixed and somewhat
> lower than fixed side, without the expense of the second wheel.
>
> Just a suggestion...
>

Cheers, a good point. Often I'm out with another cog on the flip-side
but I've never needed the bail-out option (not even on the 110M fun
run) - it's never seemed worth it for just another single gear - plus
LeVeL hubs don't do a freewheel yet (and I don't think they ever
will... :-( ).

A few gears would smooth out the steepest hills and speed up the level
sections. It's tempting.

Thanks,

Duncan

 

[Rob Morley]

In article <[email protected]>,
bookieb
[email protected] says...

> On one side, they use a track cog and lockring.
>
> On the other, a single speed freewheel, often a couple of teeth
> smaller than the fixed cog.
>
ITYM a couple of teeth larger, not smaller.

 

[[email protected]]

On Nov 6, 12:01 pm, Peter Clinch <[email protected]> wrote:
> Duncan Smith wrote:
>
> > After how many miles will a hub gear require servicing, and how much
> > would it cost (to service)?
>
> Don't know. In the 5 or so years I've had my Brom I've done, errrrr,
> zero minutes maintenance of the hub and it still seems to work okay.

In the first SRAM hub on my Brompton one of the bearings disintegrated
and dumped bits of metal in the hub which in turn resulted in the
inner compression spring getting bent. While I was trying to repair it
the sliding pin broke - not sure if this was my ham-fistedness or
whether it was the bits of bearing doing something nasty or something
else. (The primary symptom of the bearing disintegrating was the bike
ending up in "neutral" and unable to change back to any gear without
stopping and generally being unable to get the adjustment tension
right - actually I think it was bits of metal and the bent inner
compression spring preventing the various parts sliding properly
inside the hub but it felt like the tension was wrong)

In the end it was simpler to buy a new wheel because finding parts was
difficult to impossible - the hub is still in the shed waiting for a
complete set of bearings and a new sliding pin and compression spring
- the gears all look fine - fortunately the broken bits of bearing
didn't get into the gears.
http://www.woodall.me.uk/hub/img_0110.jpg

That was after about 3000 miles - I ride the bike hard - typically
30kph+ when not stopped at lights and often reaching 45-50kph on the
downhills (in central London) but I don't ride up/down kerbs or
anything else like that.

Tim.

 

[Ben Micklem]

in article [email protected], Duncan
Smith at [email protected] wrote on 6/11/07 11:36:

> My fixed frame (Pompino) has horizontal drop-outs (no in-bred sliding
> drop-outs or gear hangers).

I guess you have a 120mm OLN spaced frame. If this is the case, there are
only a few hubs that would fit- you're probably looking at 3, 4 or 5 speed
models only.

Ben

 

[Duncan Smith]

On Nov 6, 2:19 pm, Ben Micklem <[email protected]> wrote:
> in article [email protected], Duncan
> Smith at [email protected] wrote on 6/11/07 11:36:
>
> > My fixed frame (Pompino) has horizontal drop-outs (no in-bred sliding
> > drop-outs or gear hangers).
>
> I guess you have a 120mm OLN spaced frame. If this is the case, there are
> only a few hubs that would fit- you're probably looking at 3, 4 or 5 speed
> models only.
>
> Ben

I got the 135mm spacing between the frame if that helps. The SA tech
docs report axle lengths which are much greater, but no doubt that's
the length of the entire axle, not just the bit between the stays.

I'd probably go with the Rolhoff if anything, but not this year.. They
look quite pricey!

They (Rolhoff) say if you do more than 8000M per year (or km, can't
remember which) then you should consider the external gear mech - as
shown in pictures 2 and 3

http://www.rohloff.de/en/products/speedhub/index.html

I'm not sure what they mean by external gear mech?

Thanks,

Duncan

 

[Ian Blake]

On Tue, 06 Nov 2007 07:10:55 -0800, Duncan Smith
<[email protected]> wrote:

>
>I'm not sure what they mean by external gear mech?

Its the way the gear changer attachs to the hub. That little box that
the cables goes into detachs with the thumbscrew when you want to
remove the wheel.
It is a replaceable part.

 

[David Damerell]

Quoting Ben Micklem <[email protected]>:
>I guess you have a 120mm OLN spaced frame. If this is the case, there are
>only a few hubs that would fit- you're probably looking at 3, 4 or 5 speed
>models only.

The new Sturmey Archer 8-speed comes in 116mm OLN.
--
David Damerell <[email protected]> flcl?
Today is Stilday, October - a weekend.

 

[Peter Maydell]

Pete Biggs <[email protected]> wrote:
>The chain length remains constant but needs to be exactly right (within a
>few mm) for tension to be acceptable. Chain length can only be altered in
>units of a pair of links (1 inch), so you need some method of fine tuning.

You can get half-links as well. My Twenty (usual 3 speed SA AW hub) needs a
half-link to get the chain length right. I have no idea why Raleigh specced
it that way rather than making the frame slightly longer or shorter...

(I suppose in theory some previous owner might have made the change in
order to use a different size rear cog, actually. Anybody else got a folding
20 with/without the halflink?)

-- PMM

 

[Alan Braggins]

In article <CPg*[email protected]>, Peter Maydell wrote:
>
>(I suppose in theory some previous owner might have made the change in
>order to use a different size rear cog, actually. Anybody else got a folding
>20 with/without the halflink?)

I have parts of a non-folding 20, and I doubt the rear triangle is different.
But I'm not sure whether the parts include a chain.

 

[bookieb]

On Nov 6, 1:33 pm, Rob Morley <[email protected]> wrote:
> In article <[email protected]>,
> bookieb
> [email protected] says...
>
> > On one side, they use a track cog and lockring.
>
> > On the other, a single speed freewheel, often a couple of teeth
> > smaller than the fixed cog.
>
> ITYM a couple of teeth larger, not smaller.

Thanks for the correction - bit of a brain seizure on my part.

A freewheel with more teeth than the number of teeth on the fixed cog,
but those teeth to be the same size as the teeth on the fixed side,
all leading to a smaller gear.

Or something...



bookieb

 

[James Thomson]

"Peter Maydell" <[email protected]> a écrit:

> My Twenty (usual 3 speed SA AW hub) needs a half-link to get the
> chain length right. I have no idea why Raleigh specced it that way
> rather than making the frame slightly longer or shorter...
>
> (I suppose in theory some previous owner might have made the
> change in order to use a different size rear cog, actually. Anybody
> else got a folding 20 with/without the halflink?)

My aunt's Twenty came with a half link. Series 1 and 2 Moultons came with a
half link, and many older hub-geared roadsters I've seen have a half link
even when the length of the dropouts makes it unnecessary. A quick Google
finds:

http://oldroads.com/arch/ENG2003_2_238_31_17_AM.html

On many Raleighs and Raleigh built bicycles a half
link came on the chain when it left the factory.

I've often wondered why. My feeling was that it was seen as a normal feature
at the time to be able to adjust a new chain by half a link if necessary,
but vintage chains I've bought (Coventry and Renold) haven't come with a
half link in the packet, so I'm not sure that that theory holds water.

James Thomson

 

[Pete Biggs]

James Thomson wrote:
> "Peter Maydell" <[email protected]> a écrit:
>
>> My Twenty (usual 3 speed SA AW hub) needs a half-link to get the
>> chain length right. I have no idea why Raleigh specced it that way
>> rather than making the frame slightly longer or shorter...
>>
>> (I suppose in theory some previous owner might have made the
>> change in order to use a different size rear cog, actually. Anybody
>> else got a folding 20 with/without the halflink?)
>
> My aunt's Twenty came with a half link. Series 1 and 2 Moultons came
> with a half link, and many older hub-geared roadsters I've seen have
> a half link even when the length of the dropouts makes it
> unnecessary. A quick Google finds:
>
> http://oldroads.com/arch/ENG2003_2_238_31_17_AM.html
>
> On many Raleighs and Raleigh built bicycles a half
> link came on the chain when it left the factory.
>
> I've often wondered why. My feeling was that it was seen as a normal
> feature at the time to be able to adjust a new chain by half a link
> if necessary,

It's so you can adjust by removing the half link when the chain is so
stretched that you can't shove the wheel back enough to compensate.

You could argue that the chain should be replaced before it gets this worn,
but people don't do it, and chains & sprockets this worn can go on working
ok.

> but vintage chains I've bought (Coventry and Renold)
> haven't come with a half link in the packet, so I'm not sure that
> that theory holds water.

They weren't so thoughtful.

~PB

 

[[email protected]]

On 6 Nov, 11:36, Duncan Smith <[email protected]> wrote:
> Not knowing much about hub gears.. is this a feasible idea?
>
> My fixed frame (Pompino) has horizontal drop-outs (no in-bred sliding
> drop-outs or gear hangers). On some mornings if I've got to carry a
> lot to stuff in the panniers my knees feel like they could make use of
> some gears now and again.

You might want to email SA as suggested here:

http://sheldonbrown.com/asc-tech.html

It could be that a multi-speed fixed is just what you need.

Cheers,
W.
PS I have a fixie with a double chainring for two (closely spaced)
alternative gears. Same idea as a flip-flop hub but the gear ratios
are closer, because the % change in tooth count is much smaller. Mine
has a 52/48x22 for (nominal) 64" or 59" gears