Can Too High Gears be Lowered on SRAM Dualdrive?

In ,
Peter Clinch tweaked the Babbage-Engine to tell
us:

Changing from the 52 to the 42 gives a ~20% reduction to each of the
gears. There's no reason not to go /very/ low on a trike, as you're
not going to have balance issues at low speed.

Though you /may/ run out of traction, as I discovered to my cost 2/3 of the
way up the Koppenberg a few years ago :-(

--
Dave Larrington
http://www.legslarry.beerdrinkers.co.uk
I have a shell collection, have you seen it? I keep it scattered
on the world's beaches.

Peter Clinch wrote:

Roos' Dual-Drive equipped touring 'bent sports a 52 tooth front
chainring if we're going to the NL, but a 42 tooth one at home where the
hills are more freely available.

That's interesting. Is it easy to swap around like that? I know Roos has
the privilege of living with a seasoned bike expert, and perhaps is one
herself, but in my case the Darth is quite a distance away. Does not the
chain need shortening or lengthening when you change the spec on the
chainring?

EFR
Ile de France

Dave Larrington wrote:

Though you /may/ run out of traction, as I discovered to my cost 2/3 of the
way up the Koppenberg a few years ago :-(

How's that - wheels spinning around in place? Would this be because of
slippery or muddy roads, or is it a mechanical problem? Could you regain
traction by gearing up and then down again?

Cheers,

EFR
Ile de France

Artemisia wrote:

That's interesting. Is it easy to swap around like that? I know Roos has
the privilege of living with a seasoned bike expert, and perhaps is one
herself

She's pretty much as competent as me, and while you may have me as a
"seasoned bike expert" that doesn't make me a great mechanic by any
stretch of the imagination! Nevertheless, it's pretty straightforward
by our fairly, but not spectacularly, low standards.

You unhook the chain from the chainwheel, undo the bolts holding the
chainwheel onto the crank, remove it, put the new one in place and
replace the bolts. If there's a chain protector disc you'll probably
have to take that off and put it back on too, but again it's just a case
of turning bolts.

Does not the
chain need shortening or lengthening when you change the spec on the
chainring?

Potentially: to some extent the chain tensioner at the back will take up
the slack, but you may put it over its limits, depending on the size of
the step. It's easy enough to find out empirically: if your gears start
giving trouble, especially the higher ones, you'll probably need to
shorten the chain a little. That's quite easy with a chain tool. If
you get one, ask at the shop whether they have a spare bit of old chain
to practise on. I use one of Park's "foolproof" ones, and I haven't
managed to bugger it up yet, despite only using it once a blue moon. If
it's a bit scary then /any/ bike shop should be able to do the job for
you in minutes, if not seconds.

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

Artemisia wrote:
Dave Larrington wrote:

Though you /may/ run out of traction, as I discovered to my cost 2/3
of the way up the Koppenberg a few years ago :-(

How's that - wheels spinning around in place? Would this be because of
slippery or muddy roads, or is it a mechanical problem? Could you regain
traction by gearing up and then down again?

While it's worse on muddy roads, make any road steep enough and the
wheel will slip, simply a matter of not enough friction. You could
change up, but then it might be simply too hard to move the pedals!

It's worth noting that this is only a problem on /seriously/ steep hills
(see http://en.wikipedia.org/wiki/Koppenberg). But with muddy tracks
it's quite easy to run out of traction. At which point you get off and
push...

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

Peter Clinch wrote:

Artemisia wrote:
Dave Larrington wrote:

Though you /may/ run out of traction, as I discovered to my cost 2/3
of the way up the Koppenberg a few years ago :-(

How's that - wheels spinning around in place? Would this be because of
slippery or muddy roads, or is it a mechanical problem? Could you regain
traction by gearing up and then down again?

While it's worse on muddy roads, make any road steep enough and the
wheel will slip, simply a matter of not enough friction. You could
change up, but then it might be simply too hard to move the pedals!

the lane nr my folks house as it gets steeper gets worse, more holes and
during winter/spring covered with shale,and well what ever washes off
the hills. so bit of balancing act getting enought traction and so one
can still turn the cranks, still it's not a hill one uses to get from A
to B more for the i'll beat it. heh some of the folk in the village
woun't drive their cars up it. it averages 20% with peaks well into the
30% mark along with nice slippy bits, its great fun attually in a hot
sweaty, why am i doing this? kind of way

It's worth noting that this is only a problem on /seriously/ steep hills
(see http://en.wikipedia.org/wiki/Koppenberg). But with muddy tracks
it's quite easy to run out of traction. At which point you get off and
push...

looks fun in a jiggly sort of way.


Pete.

roger
--
www.rogermerriman.com

Peter Clinch wrote:

It's worth noting that this is only a problem on /seriously/ steep hills
(see http://en.wikipedia.org/wiki/Koppenberg). But with muddy tracks
it's quite easy to run out of traction. At which point you get off and
push...

My hill is seriously steep. And it's not practical to get out and pull
because on that kind of incline the SPD shoes just slip and slip, and
the bike is so heavy that it pulls me over.

I have had the trike lose traction on the dirt path that immediately
follows or precedes the killer hill. But here it was just a case of too
deep muddy goo.

EFR
Ile de France

Artemisia wrote:
Peter Clinch wrote:

It's worth noting that this is only a problem on /seriously/ steep hills
(see http://en.wikipedia.org/wiki/Koppenberg). But with muddy tracks
it's quite easy to run out of traction. At which point you get off and
push...

My hill is seriously steep.

How seriously? Koppenberg is famously difficult for
/professionals/. What's the actual gradient? There should be no
trouble with traction on a typically surfaced 20% hill, and those
are very unusual.

And it's not practical to get out and pull
because on that kind of incline the SPD shoes just slip and slip

There shouldn't be any particular trouble walking up a 20% hill in
a pair of recessed-cleat shoes as long as it isn't an expecially
slippy road.

the bike is so heavy that it pulls me over.

It's a tricycle, it can't fall over, and if it can't fall over
it'll have trouble pulling you with it!

I have had the trike lose traction on the dirt path that immediately
follows or precedes the killer hill. But here it was just a case of too
deep muddy goo.

Mud, ice, diesel, wet leaves, drain covers can have you lose
traction on level ground. You're never going to resolve all
traction problems, but that doesn't make bikes/trikes unusable.

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

In ,
Peter Clinch tweaked the Babbage-Engine to tell
us:
Artemisia wrote:
Peter Clinch wrote:

It's worth noting that this is only a problem on /seriously/ steep
hills (see http://en.wikipedia.org/wiki/Koppenberg). But with
muddy tracks it's quite easy to run out of traction. At which
point you get off and push...

My hill is seriously steep.

How seriously? Koppenberg is famously difficult for
/professionals/. What's the actual gradient? There should be no
trouble with traction on a typically surfaced 20% hill, and those
are very unusual.

Koppenberg is about 20%; the problem is that there is sand between the
cobblestones, so if the rear wheel gets into a longitudinal gap, you are
stuffed. I've done 25% a few times, most notably Bushcombe Lane:

http://preview.tinyurl.com/5mp5hu
(redirects to streetmap.co.uk)

at the start of the Cotswold Corker. I only had traction issues where it
starts to level out, due to the mud, grit, water and skog(tm) which are
frequently to be found strewn about the minor roads of the BRITONS' England
in the month of February. On the steeper bits lower down I was OK, except
for having to avoid those unable to remain upright and who were thus
toppling gracelessly into the hedge, or the front gardens of householders
unfortunate enough to live on the route.

--
Dave Larrington
http://www.legslarry.beerdrinkers.co.uk
I am Wan, for I am pursued by the Army of Plums.

Dave Larrington wrote:
In ,
Peter Clinch tweaked the Babbage-Engine to tell
us:
Artemisia wrote:
Peter Clinch wrote:

It's worth noting that this is only a problem on /seriously/ steep
hills (see http://en.wikipedia.org/wiki/Koppenberg). But with
muddy tracks it's quite easy to run out of traction. At which
point you get off and push...
My hill is seriously steep.
How seriously? Koppenberg is famously difficult for
/professionals/. What's the actual gradient? There should be no
trouble with traction on a typically surfaced 20% hill, and those
are very unusual.

Koppenberg is about 20%; the problem is that there is sand between the
cobblestones, so if the rear wheel gets into a longitudinal gap, you are
stuffed. I've done 25% a few times, most notably Bushcombe Lane:

Longstaff "double drive" sounds helpful here.

BugBear