actionbent part2

Peter Clinch wrote:


Oh dear. I'd regard him with quite a bit of suspicion, to be
honest! ;-/ When testing 'bents at Ligfietswinkel in Amsterdam the
owner cut and remade chains as needed for customers to try bikes.
He had it down to about 20 seconds. Now, practice makes perfect,
and /I/ certainly couldn't do it that fast, but 20 minutes to
shorten a chain? There just isn't any excuse.

I do (regard the mechanic hesitantly), because he seemed to be the kind
of backyard mechanic my friends are -- "good enough for government"
quality work: I told him there was a gold-colored link in the chain,
but he just undid it somewhere arbitrarily, and while joining the chain
again he didn't use the chain tool at first, but a regular
whachamacallit, that hand-held "vice" with the scissor-like
construction...while shortening the boom he used a rubber mallet but
still no cloth over the bike until at my suggestion...little things
like this.

But, to be fair, a good quarter of the time he was struggling to get
the chain back through the teflon tubing since the whole line slipped
off. =) And he hadn't worked on recumbents before, so perhaps the
novelty of it all, even though a chain is a chain is a chain, had him a
bit distracted.

If the chain itself is running smoothly with no stiff links this is
likely to be derailleur adjustment, I'd guess.

What's a "stiff" link?

I'd never had a chain follow the chain ring back up, ever!

But again I gasp in horror... 20 minutes to shorten a chain!? :-0

Yeah, and I'm really not exaggerating. But I am referring to the whole
process involved, from undoing to redoing, and at least 25% of the time
was spent trying to "thread" the chain back through the teflon tubes
and underneath the idler (that big flywheel, right?).

Nothing compared to 20 seconds, for sure, but certainly far better than
I would've been able to do, not having heard of chain tools until just
yesterday! And now, having seen it once, I at least have the framework
against which to gauge my own attempts.

Yep, I always knew a 'bent was gonna mean hands-on...just didn't expect
it quite so soon!

What's the fastest you can run yours on the flats?

At the middle gears (front and back), I seem able only to acheive 16-17
mph! This is what I do leisurely cruising along on my DF!!!

I do have on them Schwalbe Marathon Plus tires, though....

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/

NYC XYZ wrote:

SNIP


and while joining the chain
again he didn't use the chain tool at first, but a regular
whachamacallit, that hand-held "vice" with the scissor-like
construction...


AKA "pliers."

(How embarrassing!)

On 23 Apr 2006 03:16:33 -0700, "NYC XYZ"
wrote:

[snip]

I'd never had a chain follow the chain ring back up, ever!

But again I gasp in horror... 20 minutes to shorten a chain!? :-0

Yeah, and I'm really not exaggerating. But I am referring to the whole
process involved, from undoing to redoing, and at least 25% of the time
was spent trying to "thread" the chain back through the teflon tubes
and underneath the idler (that big flywheel, right?).

[snip]

Dear N,

It seems counter-intuitive, but one of the reasons for that
idler pulley and those long teflon tubes is that without
them, the chain is likely to "follow the chain ring back up"
on the unusually long chain runs of recumbents.

See this industrial chain troubleshooting list, which
includes several other causes and remedies for what we call
chain suck:

Symptoms: The chain winds onto the sprocket (poor separation
from the sprocket teeth.)

Possible Causes: Span between axles is too large.

Remedy: Install an idler.

http://chain-guide.com/basics/7-1-6-...eshooting.html

Cheers,

Carl Fogel

NYC XYZ wrote:

I do (regard the mechanic hesitantly)

snip

So why say he seems cool and you'll be back? Doesn't seem to scan...

What's a "stiff" link?

Just what it says: links should move completely freely, but a stiff
chain link has marked reluctance in pivoting relative to its neighbour.

Yeah, and I'm really not exaggerating. But I am referring to the whole
process involved, from undoing to redoing, and at least 25% of the time
was spent trying to "thread" the chain back through the teflon tubes
and underneath the idler (that big flywheel, right?).

So we're still at 15 minutes to break a chain in a couple of places and
pop it back together, which is still not very good.

What's the fastest you can run yours on the flats?

No idea, I don't have a speedo and I'm not really that interested.

At the middle gears (front and back), I seem able only to acheive 16-17
mph! This is what I do leisurely cruising along on my DF!!!

If you want to go faster, that's what the Speedmachine is for...

I do have on them Schwalbe Marathon Plus tires, though....

Shouldn't be /that/ much slower than the plain Marathons I use. Make
sure they're running at 100 psi.

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:


So why say he seems cool and you'll be back? Doesn't seem to scan...

He still knows more than me! And when I say "cool," I mean that I can
ask why he's doing something, and suggest some other way of doing
things, and he ain't offended...very easy-going personality. I can ask
questions, learn, and he didn't seem to mind. Of course, I keep it
respectful, too. I don't bother him with constant questions. But I
just get the sense I'm not dealing with a frustrated amateur racer,
know what I mean? Who'd rather be doing the Tour de France and instead
has to humor a dummy who has no mechanical inclinations at all....

Just what it says: links should move completely freely, but a stiff
chain link has marked reluctance in pivoting relative to its neighbour.

Yes, I've since found a picture that "explains" it perfectly.

So we're still at 15 minutes to break a chain in a couple of places and
pop it back together, which is still not very good.

No, I guess not...I didn't know how long it was supposed to take. But
surely you exaggerate with your claim of 20 seconds! Fixing a flat is
like five minutes, and surely cutting a chain (and then making sure
it's working right thereafter) is at least five minutes, too?

No idea, I don't have a speedo and I'm not really that interested.

I just hope I'm not more than 3 mph behind my DF on the flats -- bad as
that is (a mile is like 20 NYC blocks...3 mph less would make me a
whole neigbhorhood or two behind after an hour!).

If you want to go faster, that's what the Speedmachine is for...

I seriously doubt the SpeedMachine is that much faster...it's certainly
the same damned weight! Yes it's even more reclined, but no big deal.

I can't wait for HP Velotechnik's new machines...I'm guessing it'll be
another year or two....

Shouldn't be /that/ much slower than the plain Marathons I use. Make
sure they're running at 100 psi.

Oddly enough, the tires say that maximum psi is 70-lbs.!!!

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/

NYC XYZ wrote:

No, I guess not...I didn't know how long it was supposed to take. But
surely you exaggerate with your claim of 20 seconds!

I wasn't timing him, but I think that's a fair guesstimate. What you
have to do is wind in a lever 3 times (once for each end of the break,
once to reconnect the two ends.

Fixing a flat is
like five minutes, and surely cutting a chain (and then making sure
it's working right thereafter) is at least five minutes, too?

Fixing a flat generally means removing the wheel, unseating the tyre,
removing the inner tube, putting in a new one, reseating the tyre,
replacing the wheel, reinflating the tyre. That's a much bigger to-do
list than doing up lever to remove one pin, removing another, popping
one pin back in.

If you want to go faster, that's what the Speedmachine is for...

I seriously doubt the SpeedMachine is that much faster...it's certainly
the same damned weight! Yes it's even more reclined, but no big deal.

No, very big deal indeed. At 18 mph about 80% of your power is
overcoming air resistance, and there's significantly less frontal area
to catch the wind on a Speedmachine. There's a clue in the name!

Oddly enough, the tires say that maximum psi is 70-lbs.!!!

I'd assumed, incorrectly as it turned out, that the M+ would be the same
dimensions as the plain Marathon, but looking at the specs they are
fatter and run at lower pressures. So they will probably be slowing you
down :-(

For a still reasonably puncture proof and capable touring tyre a swicth
from the 1.75" M+ to the 1.5" Marathon running at higher pressure will
probably help you with rolling resistance and hence speed you up.

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:


I wasn't timing him, but I think that's a fair guesstimate. What you
have to do is wind in a lever 3 times (once for each end of the break,
once to reconnect the two ends.


Fixing a flat generally means removing the wheel, unseating the tyre,
removing the inner tube, putting in a new one, reseating the tyre,
replacing the wheel, reinflating the tyre. That's a much bigger to-do
list than doing up lever to remove one pin, removing another, popping
one pin back in.

But you've got to check the gears, too, afterwards, to make sure
they're shifting right and all. I don't think they did too much of
this, though...he probably checked for half a minute!

No, very big deal indeed. At 18 mph about 80% of your power is
overcoming air resistance, and there's significantly less frontal area
to catch the wind on a Speedmachine. There's a clue in the name!

Now now, we all know about names and marketing...but I didn't know 80%
of effort expended in on behalf of air resistance! Still, my point is
that I should be at least as good as a DF, given my better aerodynamics
on the SMGTe, but that's not been the case so far...even given my
Schwalbe Marathon Plus tires, the hit seems too big...I can only hope
it's a matter of developing the muscles and riding technique, as well
as those nagging chain issues (chain hop, chain suck, stiff shifting,
no shifting...it's rideable, but not smoothly so, especially for a new
machine with brand new components).

I'd assumed, incorrectly as it turned out, that the M+ would be the same
dimensions as the plain Marathon, but looking at the specs they are
fatter and run at lower pressures. So they will probably be slowing you
down :-(

For a still reasonably puncture proof and capable touring tyre a swicth
from the 1.75" M+ to the 1.5" Marathon running at higher pressure will
probably help you with rolling resistance and hence speed you up.

Yes, I knew this going in, but I figured that I'd rather have more
puncture-proof or puncture-resistance than speed, if the penalty isn't
too large and way out of proportion.

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/

NYC XYZ wrote:

But you've got to check the gears, too, afterwards, to make sure
they're shifting right and all. I don't think they did too much of
this, though...he probably checked for half a minute!

This is fair comment, but 30 seconds should be enough in the first
instance, which still leaves us rather a lot of time. Tweaking the
gears is easy enough with the adjuster screw where the gear cable
goes into the rear mech, just needs the odd tweak to tune the shifting.

Now now, we all know about names and marketing...but I didn't know 80%
of effort expended in on behalf of air resistance!

That is, IIRC, the approximate figure on a DF, though I can't
remember if that's on the hoods, in a heavy tuck or what. But it
does show approximately the degree to which speed is dominated by
aerodynamics any time you get any sort of fast.

Still, my point is
that I should be at least as good as a DF, given my better aerodynamics
on the SMGT

They're not /that/ much better. I have my seat reclined as far as
possible and it's pretty clear that cycling with pals on DF leaned
over the drops that the frontal area catching the wind isn't all
that different. When they go into a full speed crouch it's quite
obvious they have less frontal area than me.
If you want better aero, that's what the Speedmachine is for (and
to some extent, the Grasshopper).

Yes, I knew this going in, but I figured that I'd rather have more
puncture-proof or puncture-resistance than speed, if the penalty isn't
too large and way out of proportion.

To put the dangers into perspective, I've had 2 punctures on mine
in 5 years running standard Marathons. They give very good
puncture resistance. The M+ is only really an issue if you're in
Puncture Hell, otherwise they'd be standard issue rather than the
plain Marathon.

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:
NYC XYZ wrote:

[snip]

Now now, we all know about names and marketing...but I didn't know 80%
of effort expended in on behalf of air resistance!

That is, IIRC, the approximate figure on a DF, though I can't
remember if that's on the hoods, in a heavy tuck or what. But it
does show approximately the degree to which speed is dominated by
aerodynamics any time you get any sort of fast.

Still, my point is
that I should be at least as good as a DF, given my better aerodynamics
on the SMGT

They're not /that/ much better. I have my seat reclined as far as
possible and it's pretty clear that cycling with pals on DF leaned
over the drops that the frontal area catching the wind isn't all
that different. When they go into a full speed crouch it's quite
obvious they have less frontal area than me.
If you want better aero, that's what the Speedmachine is for (and
to some extent, the Grasshopper).

[snip]

Dear N & Peter,

It's common to assume that recumbents have an aerodynamic advantage
over the traditional diamond frame, but the advantage is actually
limited to fairly extreme recumbents.

You can see some of the surprising details on this speed calculator
page:

http://www.kreuzotter.de/english/espeed.htm

Hovering the mouse over the radio button for the type of recumbent will
pop up a picture that gives an idea of what a particular model looks
like. After selecting a model, clicking on calculate at the bottom will
give a predicted speed for the default values and the drag area used
for the calculation.

mph frontal type
17.1 4.3433 recumbent long wheel base
17.3 4.7889 df hands on tops
18.5 3.3781 recumbent short wheel base
19.4 3.2559 df hands on drops
20.5 2.7111 df triathlon bars
21.2 2.1748 recumbent short wheel base racer
22.3 2.0397 df superman position
23.1 1.5504 recumbent lowracer

Obviously, these are idealized guides to what a particular bike and
rider will do, with different tires and transmission efficiences
affecting things. But for the same rider and power, it takes a
recumbent that stresses speed instead of comfort to improve on the
aerodynamics of an ordinary diamond frame:

http://www.bicycleman.com/history/im...-record_lg.jpg

Cheers,

Carl Fogel

wrote:

You can see some of the surprising details on this speed calculator
page:

http://www.kreuzotter.de/english/espeed.htm

Thanks for that link, Carl.

Hovering the mouse over the radio button for the type of recumbent will
pop up a picture that gives an idea of what a particular model looks
like.

Note for this discussion that a Speedmachine would probably be somewhat
better than the "ShortWheelBase, above seat steering, racing equipped"
but not as good as "Lowracer, above seat steering". That assumes it's
the ASS SpM rather than the new USS option.

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/