Beware of PowerCranks

On Mon, 28 May 2007 09:35:02 -0500, Tim McNamara
wrote:

In article .com,
" wrote:

On May 27, 2:12 pm, Ride Faster wrote:
I had the same experience with PowerCranks. This product is
garbage.

It's really outrageous for them Powercrank to charge so much for a
faulty design.

The proprietor of PowerCranks used to post here to rebut criticisms, but
I haven't seen anything from him for a while. Basically I suspect that
the price is high because (1) he promises that his product will make you
faster for which competitive people will pay lots of money and (2) his
business is small enough that he doesn't get much by way of economies of
scale to bring his production costs down.

That is likely true.

Plus, the "design flaw" is specifically addressed in the instruction
manual. Maybe the O.P. didn't read it thoroughly - I didn't and had
my non-drive side crank arm come off during a ride early this spring.
Since I also lost the oversized crank bolt, I called the company to
order a new bolt and ask what was up. The owner personally returned
my call left on voice mail, and asked if I has used lock tite on the
bolt when I installed it. Uh, no, I replied (lock tite on a crank
bolt?). It's in the manual he replied: they do tend to vibrate off,
so we recommend blue lock tite (or similar non permanent thread
adhesive) . Plus, he also suggested this: remove the crank bolt
from your old cranks, which is used when the Powercrank is first
installed; this allows the Powercrank bolt a few extra turns for
tightness. So I followed those instructions and have had no further
issues.

About the product: the cranks ARE hugely expensive (the above
explanation makes sense to me), but they are uniquely beneficial in
terms of building leg strength and "muscle memory". You are moving
the mass of the bike and rider one leg at a time, so you must pedal in
the proverbial circle, and you must use muscles you don't normally use
to accomplish that feat. They are so hard on the legs that the first
time most people try them (I definitely recommend on a trainer), you
don't last more than 5 minutes before pain and fatigue ends your ride.
You slowly build up endurance and learn to equalize your leg speed and
timing so that you can pedal "normally", and then you can take them on
the road.

I found that spinning at higher cadences was more painful than big
gears at low cadence. Climbing a steep hill slowly hurt LESS than flat
tempo with a cadence above even 80 rpm (on these puppies, even a
molasses like 70 rpm is a bitch ). To be honest, now that the season
is in full swing I haven't been using them much, and that contradicts
the manual. It would take a long, painful effort to adjust to high
cadences. Maybe next year :-)

Even with the curtailed training, there is no question that my pedal
stroke improved after many trainer miles over the winter and spring: I
can get the "feel" of a rounder stroke. And, no question that my
climbing was better early season as well.

So I'm keeping mine and will be interested to see how far I get on
them next season.

If anybody is interested in them and saving (a bit of) money, there
are always 3 or 4 for sale on e-bay. People seem to either really
like them or really hate them.

On 26 May 2007 07:08:06 -0700, Eggs Ackley wrote:

On May 25, 10:29 pm, "Bill Sornson" wrote:
wrote:

A *grand*?!? Anyone that dumb deserves a little grief...

Boy, I'll say. I've got an Ava stem I'd like to sell this guy. Only
500 bucks! Contact me offline.

Heck, he can save money by buying my one bolt Icon stem for only $100!

Leaves that much more for the survivors.

Ron

"Tim McNamara" wrote in message
...
In article .com,
" wrote:

On May 27, 2:12 pm, Ride Faster wrote:
I had the same experience with PowerCranks. This product is
garbage.

It's really outrageous for them Powercrank to charge so much for a
faulty design.

The proprietor of PowerCranks used to post here to rebut criticisms,
but
I haven't seen anything from him for a while. Basically I suspect
that
the price is high because (1) he promises that his product will make
you
faster for which competitive people will pay lots of money and (2) his
business is small enough that he doesn't get much by way of economies
of
scale to bring his production costs down.

Frank Day. His last posts here were after a scientific study showed a
statistically significant 1.5% gross efficiency improvement. The experts
here still wouldn't buy it.

Phil H

On Sat, 2 Jun 2007 19:39:13 -0700, "Phil Holman"
piholmanc@yourservice wrote:


"Tim McNamara" wrote in message
...
In article .com,
" wrote:

On May 27, 2:12 pm, Ride Faster wrote:
I had the same experience with PowerCranks. This product is
garbage.

It's really outrageous for them Powercrank to charge so much for a
faulty design.

The proprietor of PowerCranks used to post here to rebut criticisms,
but
I haven't seen anything from him for a while. Basically I suspect
that
the price is high because (1) he promises that his product will make
you
faster for which competitive people will pay lots of money and (2) his
business is small enough that he doesn't get much by way of economies
of
scale to bring his production costs down.

Frank Day. His last posts here were after a scientific study showed a
statistically significant 1.5% gross efficiency improvement. The experts
here still wouldn't buy it.

Phil H

Dear Phil,

No offense, but that sounds like 200 watts rising to 203 watts.

Cheers,

Carl Fogel

wrote in message
...
On Sat, 2 Jun 2007 19:39:13 -0700, "Phil Holman"
piholmanc@yourservice wrote:


"Tim McNamara" wrote in message
...
In article .com,
" wrote:

On May 27, 2:12 pm, Ride Faster wrote:
I had the same experience with PowerCranks. This product is
garbage.

It's really outrageous for them Powercrank to charge so much for a
faulty design.

The proprietor of PowerCranks used to post here to rebut criticisms,
but
I haven't seen anything from him for a while. Basically I suspect
that
the price is high because (1) he promises that his product will make
you
faster for which competitive people will pay lots of money and (2)
his
business is small enough that he doesn't get much by way of
economies
of
scale to bring his production costs down.

Frank Day. His last posts here were after a scientific study showed a
statistically significant 1.5% gross efficiency improvement. The
experts
here still wouldn't buy it.

Phil H

Dear Phil,

No offense, but that sounds like 200 watts rising to 203 watts.


Hi Carl,
Run the calculation again going from 23.5% to 25%
efficiency.

Phil H

On Sat, 2 Jun 2007 21:22:45 -0700, "Phil Holman"
piholmanc@yourservice wrote:


wrote in message
.. .
On Sat, 2 Jun 2007 19:39:13 -0700, "Phil Holman"
piholmanc@yourservice wrote:


"Tim McNamara" wrote in message
...
In article .com,
" wrote:

On May 27, 2:12 pm, Ride Faster wrote:
I had the same experience with PowerCranks. This product is
garbage.

It's really outrageous for them Powercrank to charge so much for a
faulty design.

The proprietor of PowerCranks used to post here to rebut criticisms,
but
I haven't seen anything from him for a while. Basically I suspect
that
the price is high because (1) he promises that his product will make
you
faster for which competitive people will pay lots of money and (2)
his
business is small enough that he doesn't get much by way of
economies
of
scale to bring his production costs down.

Frank Day. His last posts here were after a scientific study showed a
statistically significant 1.5% gross efficiency improvement. The
experts
here still wouldn't buy it.

Phil H

Dear Phil,

No offense, but that sounds like 200 watts rising to 203 watts.


Hi Carl,
Run the calculation again going from 23.5% to 25%
efficiency.

Phil H

Dear Phil,

Ah, so it was a 6.4% difference.

As I recall, the theory was that the PowerCrank forced riders to use
muscles to raise each leg that normally weren't recruited because the
riders let their other leg do most of the work.

With more muscles involved, the theory went, things improved.

Am I right in thinking that there was an implied assumption that no
placebo effect encouraged the PowerCrank group to train harder with
their new toy for weeks than the other group, which used the same old
equipment?

That is, was there any consideration of whether the effect was due
mostly to independent crank arms or whether it was due to the crank
arms encouraging more training effort?

Cheers,

Carl Fogel

On Jun 3, 5:46 am, wrote:
On Sat, 2 Jun 2007 19:39:13 -0700, "Phil Holman"

Frank Day. His last posts here were after a scientific study showed a
statistically significant 1.5% gross efficiency improvement. The experts
here still wouldn't buy it.

No offense, but that sounds like 200 watts rising to 203 watts.

Well, the difference was in gross efficiency, not in power. Frank Day
calls them PowerCranks, not EfficiencyCranks. Phil may know whether
there has been a published RCT that shows an increase in power.

On Sat, 02 Jun 2007 22:42:15 -0600, wrote:

Am I right in thinking that there was an implied assumption that no
placebo effect encouraged the PowerCrank group to train harder with
their new toy for weeks than the other group, which used the same old
equipment?

I don't know, but no one who has just started using PowerCranks can
ride the same distance/time/speed on them as with normal cranks for at
least several months until they are used to them.
--
JT
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On Jun 3, 6:42 am, wrote:

Am I right in thinking that there was an implied assumption that no
placebo effect encouraged the PowerCrank group to train harder with
their new toy for weeks than the other group, which used the same old
equipment?

In the study, in-lab training time was equal between the PowerCranks
and control group (1 hr per day, 3 days per week, 6 weeks of
training). I guess you have to assume that the subjects weren't
spending their unobserved free time doing extra workouts in an effort
to screw with the results.

wrote in message
ups.com...
On Jun 3, 5:46 am, wrote:
On Sat, 2 Jun 2007 19:39:13 -0700, "Phil Holman"

Frank Day. His last posts here were after a scientific study showed
a
statistically significant 1.5% gross efficiency improvement. The
experts
here still wouldn't buy it.

No offense, but that sounds like 200 watts rising to 203 watts.

Well, the difference was in gross efficiency, not in power. Frank Day
calls them PowerCranks, not EfficiencyCranks. Phil may know whether
there has been a published RCT that shows an increase in power.


I just checked their website and found another study of trained cyclists
that showed a 15.6% increase in VO2max and an 11.6% icrease in max
power.

http://powercranks.com/assets/pdfs/C...dixon_2006.pdf

A test of maximum sustainable aerobic output would be nice.

I see on their website they have several more top pros using them.

Phil H