Dark Side Trike: 81 Gears Useful?

[Dave Larrington]

In news:[email protected],
Artemisia <[email protected]> tweaked the Babbage-Engine to tell us:
> 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.


If that was Ian Fardoe, I wouldn't worry too much. He's a big strong lad...

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
Odd, is it not, how all roads lead inexorably to David Icke?

 

[Artemisia]

On 6 sep, 10:07, Peter Clinch <[email protected]> wrote:
> Artemisia wrote:
> > 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.

I meant _rider_ weight and load. The Scorpion has a rather limited
load capacity, only around 275 lbs, and I can easily see myself going
near or over that, especially with luggage.

The guy tells me he's a furious spinner, and puts a lot of torque on
his trike.

I'll try writing to HPV as well. But it's SRAM I'm really interested
in hearing from, especially if they have arguments for officially not
supporting trikes and tandems.

EFR
Ile de France

 

[Peter Clinch]

Artemisia wrote:

> I meant _rider_ weight and load.

Actually easier to carry heavy loads on a Streetmachine, because there's
more space for panniers. And a rider on one can be the rider on the
other: shouldn't make any difference.

> The guy tells me he's a furious spinner, and puts a lot of torque on
> his trike.

And are you a furious spinner putting lots of torque on too? ICBW, but
my impression is probably not.

> I'll try writing to HPV as well. But it's SRAM I'm really interested
> in hearing from, especially if they have arguments for officially not
> supporting trikes and tandems.

If SRAM do say "no" it would then be worth asking HPVel why they're
using them if they're not supported. Bear in mind that an email answer
is not necessarily a definitive technical answer, it could just be a
case of someone punting a query up to the legal boys who don't know and
are having a busy day so they say "no" just to be safe, which is why I'd
follow up a "no" carefully with HPVel, who are rather smaller than SRAM
so you can pretty much guarantee you'll end up talking to an engineer
with Clues after a short 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 protected] http://www.dundee.ac.uk/~pjclinch/

 

[Brendan Halpin]

Peter Clinch <[email protected]> writes:

> Artemisia wrote:
>> The guy tells me he's a furious spinner, and puts a lot of torque on
>> his trike.
>
> And are you a furious spinner putting lots of torque on too? ICBW, but
> my impression is probably not.

That's backwards, isn't it: it's the mashers that put out high
torque, not the spinners.

Brendan
--
Brendan Halpin, Department of Sociology, University of Limerick, Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-338562; Room F2-025 x 3147
mailto:[email protected] http://www.ul.ie/sociology/brendan.halpin.html

 

[Peter Clinch]

Brendan Halpin wrote:
> Peter Clinch <[email protected]> writes:
>
>> Artemisia wrote:
>>> The guy tells me he's a furious spinner, and puts a lot of torque on
>>> his trike.
>> And are you a furious spinner putting lots of torque on too? ICBW, but
>> my impression is probably not.
>
> That's backwards, isn't it: it's the mashers that put out high
> torque, not the spinners.

All else being equal, yes. But I imagine, say, Lance Armstrong probably
puts more torque through his gears than I do at 2/3 the cadence...

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/

 

[Artemisia]

On 6 sep, 10:45, "Dave Larrington" <[email protected]>
wrote:

> If that was Ian Fardoe, I wouldn't worry too much. He's a big strong lad...

Don't know who he was. Wish he'd fess up in the ng rather than
contacting me via the back door.

BTW, glad to have you back! We were a bit worried about you for a
moment there.

EFR
Ile de France

 

[Alan Braggins]

In article <[email protected]>, Peter Clinch wrote:
> uphill most
>people run out of muscle before they topple over from balance.

They mostly don't have 81 gear bikes though.

 

[Peter Clinch]

Alan Braggins wrote:
> In article <[email protected]>, Peter Clinch wrote:
>> uphill most
>> people run out of muscle before they topple over from balance.
>
> They mostly don't have 81 gear bikes though.

It's not really relevant how many gears you have, it's how fast you're
going that will determine if you topple a bike over up a steep hill.

And IME people just get fed up and walk before they reach that point.

I recall one incident when a pal and I were taking our MTBs up a fairly
steep grassy field. I got bored at walking pace, and decided I'd walk.
While walking, I soon overtook my pal, still spinning happily in 1st...

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/

 

[Aeek]

On 06 Sep 2007 14:03:35 +0100 (BST), [email protected] (Alan
Braggins) wrote:

>In article <[email protected]>, Peter Clinch wrote:
>> uphill most
>>people run out of muscle before they topple over from balance.
>
>They mostly don't have 81 gear bikes though.

I have a 24-32 granny on the 700c tourer, good for 4kmh up hill.
No problems with balance.
Taking a rest is the problem, I can't get up to 4kmh fast enough to
get going again in the granny.

 

[Clive George]

"Peter Clinch" <[email protected]> wrote in message
news:[email protected]...

> I recall one incident when a pal and I were taking our MTBs up a fairly
> steep grassy field. I got bored at walking pace, and decided I'd walk.
> While walking, I soon overtook my pal, still spinning happily in 1st...

What is it about going up grassy fields which makes them such hard work?
(yes, I know the answer really, but it still amuses me that such innocuous
looking terrain takes so much effort).

cheers,
clive

 

[Alan Braggins]

In article <[email protected]>, Peter Clinch wrote:
>Alan Braggins wrote:
>> In article <[email protected]>, Peter Clinch wrote:
>>> uphill most
>>> people run out of muscle before they topple over from balance.
>>
>> They mostly don't have 81 gear bikes though.
>
>It's not really relevant how many gears you have, it's how fast you're
>going that will determine if you topple a bike over up a steep hill.

Right, and with lower gears and the same amount of muscle, you can
more easily not run out of muscle by going slower.


>And IME people just get fed up and walk before they reach that point.

Less so if they have a recumbent trike to walk, I suspect.

 

[Peter Clinch]

Alan Braggins wrote:

> Right, and with lower gears and the same amount of muscle, you can
> more easily not run out of muscle by going slower.

If you run out more easily or less easily, if you still run out before
you'd topple it's a moot point.

> Less so if they have a recumbent trike to walk, I suspect.

But as further discussions have demonstrated you can actually get a
bigger overall range and attendant lower gears in other ways than having
81 gears via a triple front and DD at the back. 81 gears is a possible
approach but a rather baroque and not optimum one.

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/

 

[Clive George]

"Peter Clinch" <[email protected]> wrote in message
news:[email protected]...

> But as further discussions have demonstrated you can actually get a
> bigger overall range and attendant lower gears in other ways than having
> 81 gears via a triple front and DD at the back. 81 gears is a possible
> approach but a rather baroque and not optimum one.

Greenspeed (used to?) do it. He said he didn't want to use a huge ring on
the front to compensate for the little back wheel, since it wouldn't shift
as well. This was about 10 years ago mind. OTOH it's rather cheaper than the
mountain/speed drive options.

cheers,
clive

 

[Artemisia]

Alan Braggins wrote:
> In article <[email protected]>, Peter Clinch wrote:

>>And IME people just get fed up and walk before they reach that point.

> Less so if they have a recumbent trike to walk, I suspect.

If only because they have such a hard time getting up!

EFR
Ile de France

 

[Artemisia]

Clive George wrote:

> Greenspeed (used to?) do it.

They still do on the GT0, SRAM DD on the back and Sturmey Archer on the
front.

EFR
Ile de France

 

[Mike A Schwab]

On Sep 5, 3:40 pm, Artemisia <[email protected]> wrote:
> 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

I have an EZ-1 recumbent 16/20. Came with a 3 * 8 derailer, LBS had a
DD from a wheel that blew a rim, they built a wheel around it, with a
11-34 megarange cassette. I almost always stay in the middle internal
gear, the internal losses are quite noticable in high and low gear.
Even when I spin out the top gear, shifting the internal into
overdrive slows me down. But the underdrive on steep hills or if I
stop in a mid to high gear is quite useful.

 

[Artemisia]

On 5 sep, 22:40, Artemisia <[email protected]> wrote:

> 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.

Still haven't heard from SRAM. I phoned HPV this morning. The guy told
me they had had a lot of problems with the SRAM drives and that SRAM
was over there non-stop, checking and revising, but that they have
solved the glitches now. Still, the guy sounded nervous, like he felt
I was grilling him on a known issue...

EFR
Ile de France

 

[Nigel Cliffe]

Artemisia wrote:
> On 5 sep, 22:40, Artemisia <[email protected]> wrote:
>
>> 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.
>
> Still haven't heard from SRAM. I phoned HPV this morning. The guy told
> me they had had a lot of problems with the SRAM drives and that SRAM
> was over there non-stop, checking and revising, but that they have
> solved the glitches now. Still, the guy sounded nervous, like he felt
> I was grilling him on a known issue...

Given the way your conversations are heading, suggesting problems with the
SRAM dual-drive, why not explore the other "fairly simple" options, even if
they require a rear wheel which isn't on the standard HPV list:


Schlumpf + 9 speed rear.

Schlumpf + cheaper hub gear, such as Shimano 8, or SRAM 7. This has the
"change when stopped" functionality of hub gears. Schlumpf's website shows
High-Speed-Drive + SRAM 7 combined to give 1.3m to 9.9m fairly evenly spaced
on a 20" wheel.




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

 

[Artemisia]

Nigel Cliffe wrote:

> Given the way your conversations are heading, suggesting problems with the
> SRAM dual-drive, why not explore the other "fairly simple" options, even if
> they require a rear wheel which isn't on the standard HPV list:

Because it would actually cost more than to go with the standard
fitting. The base price (which includes the SRAM) stays the same, and
then we'd have to add not only the Schlumpf but the Nexus as well.

Also, I might not be happy running with just a Nexus until such a time
as I can afford the Schlumpf. Between now and Schlumpf I do want to ride
the bike...

Schlumpf's website shows
> High-Speed-Drive + SRAM 7 combined to give 1.3m to 9.9m fairly evenly spaced
> on a 20" wheel.

That is a good range. I wish I could figure out what it would be with
the SRAM DD. I'm a little put off by the fact that the gain in gears
comes entirely at the low end. The top developments of the SRAM DD could
use some good boosting as well. I should like to be able to at least
equal the range of the "Baroque" 81 speed setup, which is 0.98M to 9.81m.

EFR
Ile de France

 

[Nigel Cliffe]

Artemisia wrote:
> Nigel Cliffe wrote:
>> Given the way your conversations are heading, suggesting problems with
>> the SRAM dual-drive, why not explore the other "fairly simple" options,
>> even if they require a rear wheel which isn't on the standard HPV list:

> Because it would actually cost more than to go with the standard fitting.
> The base price (which includes the SRAM) stays the same, and then we'd
> have to add not only the Schlumpf but the Nexus as well.

Is that because nobody will supply you a bike without a rear wheel, or
credit you at least some of the value of the unused rear wheel components ?


>> Schlumpf's website shows
>> High-Speed-Drive + SRAM 7 combined to give 1.3m to 9.9m fairly
>> evenly spaced on a 20" wheel.
>
> That is a good range. I wish I could figure out what it would be with
> the SRAM DD.

Sheldon Brown will give you the figures:
http://sheldonbrown.com/gears/

Put in the wheel size, then select cassette and the hub gear, and a tooth
count for the front chainring.

An 8 (24 total) speed SRAM DD, with an 11-30 cassette and 50T front ring
gives 1.8 to 9.2m
A 9 (27 total) speed SRAM DD, with an 11-32 cassette and 50T front ring
gives 1.7 to 9.2


> I'm a little put off by the fact that the gain in gears
> comes entirely at the low end. The top developments of the SRAM DD
> could use some good boosting as well.

The SRAM DD is limited by the fixed ratios of the 3-speed hub component.

You can alter the top and bottom at the same time by replacing the front
chainring. Larger for higher ratio, or smaller for lower, but all gears will
move.

The only way to widen the range is to fit a wide-range cassette onto the
drive. I don't know the maximum cassette which will fit the SRAM hub. The
maximum 8-speed cassette range from Shimano would be an 11-34 "mega-range".
Assuming that cassette would fit the SRAM hub, the lowest gear drops to 1.6m
(leaving the top at 9.2m). But mega-range cassettes are often criticised
for the large jump in ratio, making the change to the bottom ratio rather
abrupt.


> I should like to be able to at
> least equal the range of the "Baroque" 81 speed setup, which is 0.98M
> to 9.81m.

I doubt this is possible with the DD on its own. It is designed to achieve
a 500-odd percent range, which is the same as most wide-ratio touring bikes
with derraileur gears.


If you are sticking with the SRAM DD, then the practical way to extend the
range is one of the following:

The Schlumpf.
A 2-ring chainset (rather than 3), with something such as a 53/39 "racing
road" ratio, which would give an overall range of 1.3 to 9.8m.

Either of the above isn't quite as complicated as a triple front, but still
gives more combinations than I think sensible when combined with 24 or 27 at
the rear and the SRAM DD.




- Nigel


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