Dark Side Trike: 81 Gears Useful?

Artemisia said:

"drivetrain DualDrive XT-81 81 speed rear derailleur XT / cassette
XT / DualDrive 3 speed hub / bar end shifters / grip shifter for
DualDrive gear development 0,98 - 9,81 m (3'3'' - 32'3'😉"

I will be taking this trike up some very steep hills. I'm looking
forward to being able to use very low gears, much lower than would
allow me to remain upright on a 2-wheeler.

However, when I spoke to a dealer in Angers about this option, he told
me he didn't think it was very useful, insofar as the gear range would
not be that much greater than with the SRAM Dualdrive alone, that is
fitted as standard, and that most of the gears would be overlapping
anyway.

He's right about the overlapping (and then some), but wrong about the
overall range. The front triple is 60/52/40, so that gives a 60/40 =
1.5 difference in gearing from using the big ring or small ring, so
that's half as much gear range again as without the front triple.

But it's a rather odd setup... You could have, say, a 50/34 compact
double at the front for pretty much the same degree of useful effect,
less weight, less confusion and less cost.

Quoted message said:

Unfortunately HPV doesn't offer Schlumpf Mountain Gearing, which
sounds like it could be the option delivering the widest range.

Not in their standard price list, but a Schlumpf dealer should be able
to fit one for you. I know that Kinetics have put several Schlumpfs
into HPVels so there's nothing intrinsically problematical about it.

Quoted message said:

Anyway, what do does the ng think? Does this 81 speed setup really
deliver an advantage over the standard 24 speed?

Up to a point. I think it's an odd selection of front rings and will be
rather complicated and fussy in use to get optimum gearing. I'd be much
more inclined to put in a Rohloff with a twin front derailleur to give
you that sort of range as it will be much easier to use and maintain and
probably be more efficient and lighter too. Replace the front
derailleur with a Schlumpf to pretty much eliminate maintenance other
than a new chain every one in a while and to give you practically zero
chance of throwing a chain.

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 hidden] http://www.dundee.ac.uk/~pjclinch/

Artemisia said:

Me again, one more question.

I am assuming that I will order the Scorpion FX with the option of a
Sram Dualdrive on the back and a three-speed cassette on the front.
The Price List stipulates:

"drivetrain DualDrive XT-81 81 speed rear derailleur XT / cassette
XT / DualDrive 3 speed hub / bar end shifters / grip shifter for
DualDrive gear development 0,98 - 9,81 m (3'3'' - 32'3'😉"

I will be taking this trike up some very steep hills. I'm looking
forward to being able to use very low gears, much lower than would
allow me to remain upright on a 2-wheeler.

However, when I spoke to a dealer in Angers about this option, he told
me he didn't think it was very useful, insofar as the gear range would
not be that much greater than with the SRAM Dualdrive alone, that is
fitted as standard, and that most of the gears would be overlapping
anyway.

Putting all you have said into Sheldon Brown's gear calculator
(http://sheldonbrown.com/gears/) gives a massive table of gears, but
essentially:

The Dual Drive system on its own, with an 11-32 cassette at the rear gives
about a 500% gear range. This is comparable to the range in a Rohloff hub,
or a wide-range touring road bike.

How this manifests itself depends on the tooth count of the front chainring
and the diameter of the rear wheel.

So, I assumed a 40T front and a 20inch rear wheel, the range is 1.4m to
7.4m.

1.4m is pretty low for bottom gear. However, on a trike you can go as low as
you like without falling off !
For most people on a two-wheeled machine they would have trouble balancing
at 1.4m, 1.8 being a more typical bottom range of a mountain bike.

7.4m is moderately low for top gear. I would expect to be able to just pedal
to 50kph with a 7.4m gear on a downhill, though my legs would be spinning
very very quickly. I would prefer a top gear nearer to 8.5-9m. I would see
no reason to go massively above 9m for a touring bike.

From the above, my personal choice would be to use a front sprocket of 48T,
making the overall gearing a bit higher (1.6 to 8.9). But in making that
decision, you'd need to take into account the exact rear wheel size (which I
may have estimated incorrectly) and your personal preference for bottom and
top gears.

Adding a triple front chain ring set, whilst this gives you 81 gears, about
75 of them are within the range offered by the Dual-Drive on its own. You
only gain three or four steps at the extremes. I doubt that many of the 75
in the middle offer any advantage over 27; most will be indistinguishable
from the gears already present. Therefore, I tend to agree with your dealer
that the extra steps offered by combining both is marginal.

Quoted message said:

Flyzipper has the simple SRAM Dualdrive three by seven. Admittedly I
have never used the lowest of his 24 gears. I do find myself spinning
out on his highest gears, however, on some of those long smooth Czech
descents.

A problem which could be corrected by changing the front chain-ring for a
larger size. Thus the lowest gears would be a bit higher, and the largest
gear even higher.

Quoted message said:

It also appears that the front gears would not be changeable at a
standstill, which is a disadvantage in comparison to the Greenspeed
GT0 setup which combines a SRAM DualDrive in the back with a Sturmey
Archer in the front. The Scorpion 81-speed would have only the three
SRAM levels on the back that could be shifted at a standstill.

Correct.

Quoted message said:

Unfortunately HPV doesn't offer Schlumpf Mountain Gearing, which
sounds like it could be the option delivering the widest range.

This should be retro-fittable by a competant dealer.

Quoted message said:

Anyway, what do does the ng think? Does this 81 speed setup really
deliver an advantage over the standard 24 speed?

Thanks again for all your expertise.

EFR
In hilly Ile de France

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

Nigel Cliffe said:

Quoted message said:

Unfortunately HPV doesn't offer Schlumpf Mountain Gearing, which
sounds like it could be the option delivering the widest range.

This should be retro-fittable by a competant dealer.

and

Peter Clinch said:

Replace the front
derailleur with a Schlumpf to pretty much eliminate maintenance other
than a new chain every one in a while and to give you practically zero
chance of throwing a chain.

So if I'm reading this correctly, you both think the provided 81-gear
setup is a redundant mess, but that I could probably do quite well
ordering the standard SRAM 27-gear setup and getting a Schlumpf
mountain gear retrofitted at a later date if needed?

This would have the added advantage that I could split the payments.
The Schlumpf part could come next year, after my bank account has
recovered a little, and I could lighten up the bill to be paid up by
the end of 2007.

(Can't afford a Rohloff, Peter, alas.)

EFR
Ile de France

Artemisia said:

Nigel Cliffe said:

Quoted message said:

Unfortunately HPV doesn't offer Schlumpf Mountain Gearing, which
sounds like it could be the option delivering the widest range.

This should be retro-fittable by a competant dealer.

and

Peter Clinch said:

Replace the front
derailleur with a Schlumpf to pretty much eliminate maintenance other
than a new chain every one in a while and to give you practically zero
chance of throwing a chain.

So if I'm reading this correctly, you both think the provided 81-gear
setup is a redundant mess

I can't speak for Nigel, but I'd put my own position not at "redundant
mess", but rather "there /are/ clear benefits but it seems excessively
baroque for what those benefits are", and it is not an avenue I would
choose myself. I'd just keep it simpler with a DD, and freewheel on the
really big downs.

Quoted message said:

but that I could probably do quite well
ordering the standard SRAM 27-gear setup and getting a Schlumpf
mountain gear retrofitted at a later date if needed?

Yes.

Quoted message said:

(Can't afford a Rohloff, Peter, alas.)

I know /exactly/ how you feel! ;-/

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 hidden] http://www.dundee.ac.uk/~pjclinch/

Nigel Cliffe said:

So, I assumed a 40T front and a 20inch rear wheel, the range is 1.4m to
7.4m.

Would it be possible to use a SRAM DD with a Sclumpf Mountain, but to
change the sprocket range on the DD so as to gear higher? Because I'm
assuming the Schlumpf will fill in a lot of speeds _underneath_ the
SRAM setup (24sp, not 27 as I initially mistook), but nothing _over_.
So moving the SRAM into an overall higher speed range with a Schlumpf
might give an overall wider range than with the existent SRAM, a
little deficient at the high end?

EFR
Ile de France

Artemisia said:

Me again, one more question.

I am assuming that I will order the Scorpion FX with the option of a
Sram Dualdrive on the back and a three-speed cassette on the front.
The Price List stipulates:

"drivetrain DualDrive XT-81 81 speed rear derailleur XT / cassette
XT / DualDrive 3 speed hub / bar end shifters / grip shifter for
DualDrive gear development 0,98 - 9,81 m (3'3'' - 32'3'😉"

I will be taking this trike up some very steep hills. I'm looking
forward to being able to use very low gears, much lower than would
allow me to remain upright on a 2-wheeler.

However, when I spoke to a dealer in Angers about this option, he told
me he didn't think it was very useful, insofar as the gear range would
not be that much greater than with the SRAM Dualdrive alone, that is
fitted as standard, and that most of the gears would be overlapping
anyway.

Flyzipper has the simple SRAM Dualdrive three by seven. Admittedly I
have never used the lowest of his 24 gears. I do find myself spinning
out on his highest gears, however, on some of those long smooth Czech
descents.

It also appears that the front gears would not be changeable at a
standstill, which is a disadvantage in comparison to the Greenspeed
GT0 setup which combines a SRAM DualDrive in the back with a Sturmey
Archer in the front. The Scorpion 81-speed would have only the three
SRAM levels on the back that could be shifted at a standstill.

Unfortunately HPV doesn't offer Schlumpf Mountain Gearing, which
sounds like it could be the option delivering the widest range.

Anyway, what do does the ng think? Does this 81 speed setup really
deliver an advantage over the standard 24 speed?

Thanks again for all your expertise.

EFR
In hilly Ile de France

Isn't 81 gears a bit much?

Eric

Artemisia said:

Would it be possible to use a SRAM DD with a Sclumpf Mountain, but to
change the sprocket range on the DD so as to gear higher?

I guess it would take a different cassette, but it would be /much/
easier to just put a bigger chainwheel on the front end, which should be
no big deal at all on a Mountain Drive.

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 hidden] http://www.dundee.ac.uk/~pjclinch/

Artemisia said:

Nigel Cliffe said:

Quoted message said:

Unfortunately HPV doesn't offer Schlumpf Mountain Gearing, which
sounds like it could be the option delivering the widest range.

This should be retro-fittable by a competant dealer.

and

Peter Clinch said:

Replace the front derailleur with a Schlumpf to pretty much
eliminate maintenance other than a new chain every one in a while
and to give you practically zero chance of throwing a chain.

The Schlumpf, while a good solution, is bloody expensive. ~400 euros to
get it delivered.

Quoted message said:

So if I'm reading this correctly, you both think the provided 81-gear
setup is a redundant mess, but that I could probably do quite well
ordering the standard SRAM 27-gear setup and getting a Schlumpf
mountain gear retrofitted at a later date if needed?

This would have the added advantage that I could split the payments.
The Schlumpf part could come next year, after my bank account has
recovered a little, and I could lighten up the bill to be paid up by
the end of 2007.

(Can't afford a Rohloff, Peter, alas.)

You're in danger of spending the same amount of money a Rohloff would
cost in the first place imho.

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

Quoted message said:

Isn't 81 gears a bit much?

Eric

I've got 82 but that's on 4 cycles.

--
Cheers,
the.Mark

Tosspot said:

The Schlumpf, while a good solution, is bloody expensive. ~400 euros to
get it delivered.

Quoted message said:

You're in danger of spending the same amount of money a Rohloff would
cost in the first place imho.

Doesn't look like it - the Rohloff option on the HPV price-list costs
1049€, considerably more than the Schlumpf! And I'm thinking Schlumpf +
Dualdrive might give me more range than a Rohloff.

EFR
Ile de France

Does anyone actually have a SRAM DualDrive on a recumbent trike? I've
just had an alarming report from someone off-list that SRAM themselves
don't warranty DualDrives on trikes and that he fried two of them on his
trike and would never have one again.

I have of course contacted SRAM to see what they say. If it turns out
that they won't even guarantee the DualDrive on recumbent trikes despite
the DD being standard fitting on many in that class of machines, then I
may have to rethink the whole project.

EFR
Ile de France

Artemisia said:

Tosspot said:

The Schlumpf, while a good solution, is bloody expensive. ~400 euros
to get it delivered.

Quoted message said:

You're in danger of spending the same amount of money a Rohloff would
cost in the first place imho.

Doesn't look like it - the Rohloff option on the HPV price-list costs
1049€, considerably more than the Schlumpf! And I'm thinking Schlumpf +
Dualdrive might give me more range than a Rohloff.

My thought[1] was wouldn't the rohloff with a single ring do the job?
Like I said, I've not run up the spread sheet to do the gear
inches/metres developed/squirrels flattened calculation.

Actually, I do have the schlumpf drive on my trike, not to lower the
ratio, but to stop it spinning out at around 25-30 kph, so I guess I'm
not one to comment 🙁

But the rohloffs are nice....

[1] I've had a few beers >🙂=

Artemisia said:

Does anyone actually have a SRAM DualDrive on a recumbent trike? I've
just had an alarming report from someone off-list that SRAM themselves
don't warranty DualDrives on trikes and that he fried two of them on
his trike and would never have one again.

No idea.

I had a 3x7 version on a recumbent bike (sold some years ago). The
three-speed hub bit proved very useful if I forgot to change down at
junctions. But I did notice transmission drag when in gears 1 or 3 on the
hub gear.

I had no mechanical issues with it, but I am fairly light at 68kg and didn't
take the bike on laden tours.

Quoted message said:

I have of course contacted SRAM to see what they say. If it turns out
that they won't even guarantee the DualDrive on recumbent trikes
despite the DD being standard fitting on many in that class of
machines, then I may have to rethink the whole project.

Sensible given the cost of the project.

- Nigel

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

Artemisia said:

So if I'm reading this correctly, you both think the provided 81-gear
setup is a redundant mess, but that I could probably do quite well
ordering the standard SRAM 27-gear setup and getting a Schlumpf
mountain gear retrofitted at a later date if needed?

Just a thought on the Shlumpf option. IIRC the only one suitable for a
Rohloff is the Speed Drive. The Mountain and High Speed drives can
exceed the design limits of the Rholoff. Do any similar limitations
apply to the SRAM system?

--
Don Whybrow

Sequi Bonum Non Time

Give your child mental blocks for Christmas.

Peter Clinch said:

Artemisia said:

Nigel Cliffe said:

> Unfortunately HPV doesn't offer Schlumpf Mountain Gearing, which
> sounds like it could be the option delivering the widest range.
This should be retro-fittable by a competant dealer.

and

Peter Clinch said:

Replace the front
derailleur with a Schlumpf to pretty much eliminate maintenance
other than a new chain every one in a while and to give you
practically zero chance of throwing a chain.

So if I'm reading this correctly, you both think the provided 81-gear
setup is a redundant mess

I can't speak for Nigel, but I'd put my own position not at "redundant
mess", but rather "there /are/ clear benefits but it seems excessively
baroque for what those benefits are", and it is not an avenue I would
choose myself. I'd just keep it simpler with a DD, and freewheel on
the really big downs.

I concur, 81 gears is a very complicated system which struggles to justify
its benefits.

I might look at the costs and benefits of few other "simple" options as
well:
Rohloff alone (even if expensive).
Conventional 8/9 speed derraileur rear + Schlumpf front.
8/9 speed hub rear (Shimano/SRAM) + Schlumpf front.
8/9 speed hub rear + 2-ring derraileur front (probably barmy, but I would
think about it).

- Nigel

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

Artemisia said:

Does anyone actually have a SRAM DualDrive on a recumbent trike? I've
just had an alarming report from someone off-list that SRAM themselves
don't warranty DualDrives on trikes and that he fried two of them on his
trike and would never have one again.

Not a trike, but we've got one on a four-wheeled bike (Brox). Why
should the extra wheels fry them, though?

-dan

Daniel Barlow said:

Artemisia wrote:

Quoted message said:

Not a trike, but we've got one on a four-wheeled bike (Brox). Why
should the extra wheels fry them, though?

I don't think it's the extra wheels; rather the extra weight, and the
fact that one can attempt a greater range of tracks including much
steeper uphills and downhills. In addition to being very heavy myself
I want to take this trike on laden tours.

EFR
Ile de France

Artemisia said:

Does anyone actually have a SRAM DualDrive on a recumbent trike? I've
just had an alarming report from someone off-list that SRAM themselves
don't warranty DualDrives on trikes and that he fried two of them on his
trike and would never have one again.

While nobody has actually owned up here, I would think in the wider
context the answer is "probably the majority of Scorpion riders", since
it is HPVel's default gearing setup.
I suspect that (a) they tested it fairly well, (b) wouldn't supply
something that they can't back up, (c) wouldn't persist in using
something that's inherently unreliable and (d) know the track record of
quite a lot of vehicles fitted with it via warranty claims they get sent.

So I'd ask them, and make sure they'll stand behind what they supply.

The report you have is a single anecdote. When it comes to
mass-produced complex engineering you can /always/ find someone who
doesn't get on with something, and even Rolls Royce will make the odd lemon.

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 hidden] http://www.dundee.ac.uk/~pjclinch/

Artemisia said:

I don't think it's the extra wheels; rather the extra weight

I doubt that. Weight is listed as "from 16.6 Kg" which is really not
especially heavy in the wider context of "all bikes", and you don't have
to look very hard to find bikes in the same weight range.

The Streetmachine is "from 15.2 Kg" for example, and if you look at
bikes where no real attempt has been made on lightness I think you could
easily get over that.

Quoted message said:

and the
fact that one can attempt a greater range of tracks including much
steeper uphills and downhills.

And I doubt that too. You can attempt anything on anything, spinning
out on the downhills puts no pressure on the gears and uphill most
people run out of muscle before they topple over from balance.

Quoted message said:

In addition to being very heavy myself
I want to take this trike on laden tours.

There's no shortage of big people touring on /very/ well laden bikes.

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 hidden] http://www.dundee.ac.uk/~pjclinch/