Please don’t hijack this thread and make it yet another PC bashing… I’m niether supporting PC’s nor discrediting them. I’m a CT user and was just wondering.
Anyone have any “real life” experience on what PC’s do to spinscan numbers on the computrainer?
Mine aren’t that much different than with regular cranks. Generally a 49/51 or 50/50 split right/left with a spin scan number in the low to mid 70s with or without the powercranks.
It’s been several months since I rode the powercranks though. Spinscan isn’t perfect, but I do think that it gives a reasonable amount of feedback. I don’t think that you can use spinscan as a substitute for powercranks though…there’s not really anything that is a coparable substitute for the powercranks.
$0.02 worth.
Please don’t hijack this thread and make it yet another PC bashing… I’m niether supporting PC’s nor discrediting them. I’m a CT user and was just wondering.
Anyone have any “real life” experience on what PC’s do to spinscan numbers on the computrainer?
First you have got to ask the question, how do you
get the highest spinscan number; by reducing your
maximum power application around the 3 o’c area
to the minimum force that you apply at 12 and 6
and not unweighting the rising pedal ???
Personal observation: my peaks are higher after training on PC’s with about the same valleys, i.e., my pedalling is not as smooth. Obviously, overall wattage increased. That’s right, my pedal stroke is less smooth after PC training. This is because I no longer push up my rising leg with the downstroke other leg…actually, it appears I was attenuating a powerful downstroke in order to produce a smoother overall stroke. Now, I get that rising leg out of the way and get higher peaks on the downstroke. What I learned is that smoothness at the expense of power is not a good thing. BTW, this was done on regular cranks. If you’re asking what would happen if powercranks were used on the computrainer, that would probably be a different answer…one that I have not actually seen.
perfection wrote: First you have got to ask the question, how do you
get the highest spinscan number; by reducing your
maximum power application around the 3 o’c area
Yep, you’re on the right track…that’s what I was trying to say about being smooth for the sake of smoothness. “Smoother” isn’t neccessarily better. Sure, if you can increase you wattage by raising the valley seen on the spin scan while keeping the peak the same, THAT “smoother” would be better. But, if you increase wattage by getting higher peaks with the same valleys, THAT “smoother” isn’t better. Of course, you’d like to try and do both!
So what you’re saying is that pedalling in circles is not very efficient. Now if PC’s teach you to pedal in circles…? Or am I losing something here?
I don’t think I have an issue with my spinscan numbers. I normally average around 78/80 for a 60 min ride on the CT. Anything over an hour gets harder to maintain those numbers, eventually around 90 min I’m avg around 74/75, 2 hours I’m spinning around 70-72. After about two hours it takes extreem concentration to maintain anything over 70 consistently. I’ve only been back on the bike for 2 years, and I’ve been riding the CT for a little over a year now and I’ve been thinking about PC’s forcing me to spin properly or get my ass off the bike. Otherwise it’s just continued training to continue to build endurance of all my muscles for higher spinscan numbers for longer periods of time.
sac wrote: So what you’re saying is that pedalling in circles is not very efficient…
Not at all. I’m saying PC training taught me to quit being smooth by attenuating the upstroke. PC training “released” that downstroke power to go to the chain, rather than to be used to push up the rising foot. I imagine that further training on PC’s might allow me to raise the valley of the spin-scan graph. Others may already have been doing a better job at pulling up…PC’s just force you to at least pull up enough to get that rising leg out of the way.
OK, I was just testing your faith 
But you do know that this “unloading” also is found on non-PC riders, it’s a natural results of pedalling with normal cranks.
I’m still not so sure what all the big hype about PC is. My hip-flexors are pretty damn sore after long rides. Just focus on pedaling in circles and imagine it in your mind.
One-legged drills are good too.
There I saved you 800 dollars.
sac wrote: OK, I was just testing your faith
Did I pass? 
Like I’ve said before, PC’s may only help people with screwed up pedal strokes…like me. However, maybe they can also help people with darn good pedal strokes…I’ll have to leave that call up to those with darn good pedal strokes to begin with!
I am curious what a spin-scan would look like with Rotor Cranks…i.e., do Rotors result in a higher valley, a higher peak, or both? (Or neither?) If it’s a higher valley, then the idea that they lessen the “dead spot” would be correct in how they work. But, if the valley stays the same and the peak is higher…or the area under the peak is greater, then THAT would be how they work. Maybe they do both. Of course, it may depend upon each individual rider’s pedal stroke.
As far as PC’s on a computrainer: I find that no matter how much I train on PC’s, after a while, it is apparent that the rising pedal is slightly slower to the top…I know this because the “peg” on the large chainring gradually moves further and further in front of the right crankarm…that means I’m slow getting to the top. (I’m assuming the same is true on the left, there just isn’t a marker that I can see to tell.) So, using PC’s on a computrainer might show that the area under the curve is slightly greater in my stroke, which would go along with what I see on the road…as long as my position is similar on a PC bike and a regular-crankset bike, my speed is slightly faster on the PC bike…as long as I’m pedalling…and THOSE two things are the key: Same position, continuous pedalling.
I have not worked on adaptation with PC’s in the aero position. I have adapted pretty well on PC’s, but, I still have to rest a little every 15-20 minutes. After about 1-1.5 hours, my hip flexors are getting toasted, and I have to rest them more and more often. So, I’m certainly not a poster-boy for optimal PC training. One big reason is that my neck pain/numbness is aggravated by riding on my road bike, and that’s the bike my PC’s are on. Lucky for me, I can ride in the aero position for much longer before my neck pain makes me stop, so I can do longer triathlons…but, it limits the length of my PC rides.
This computrainer stuff might provide some decent information if someone had access to the different cranks, and had trained on PC’s enough to become somewhat adapted.
sac wrote: But you do know that this “unloading” also is found on non-PC riders, it’s a natural results of pedalling with normal cranks?
Yep, in some people. In my pedal stroke? Obviously not. I had a well-known fitter/coach/advisor to some very accomplished national/international riders, evaluate my pedal stroke Pre-PC training. He said I had a smoother stroke than 95% of all the people he’d ever seen, yet I didn’t TT well…although I road-raced very well…I literally never lost a sprint finish in my entire life (which only consists of maybe 50 races, and NONE of them high-level, I am not a bike-racing phenom). The point is, if I had such a good, smooth pedal stroke at 108 rpms (that’s where I felt the best), why wasn’t I TT’ing better? OK, we dropped the rpms and I went faster, but, not very fast compared to people I would whip in a road race. I got PC’s (not at this coach’s advice, I don’t know what he thinks about them), and BOOM! Gained almost 2mph on my TT in about 8 months, and my run splits plummeted within two weeks. Turns out my smooth stroke was a wasting-power stroke. That’s my point.
So, take someone like me, and PC’s may unleash that wasted power…I’ll never try to be smooth just to be smooth again! Take someone like Devashish Paul, (i.e., someone really good to begin with) and ask if PC’s help him…maybe they do, maybe they don’t, I don’t know, maybe he doesn’t know. But, I do know they help some people profoundly.
Rotors are a different animal. I’d love to get on a computrainer and compare graphs between all three cranksets. Of course, a well-adapted PC’er on regular cranks may not show any difference (at least for a while) between those PC’s and regular cranksets. It would be interesting to do.
So what you’re saying is that pedalling in circles is not very efficient. Now if PC’s teach you to pedal in circles…? Or am I losing something here?
What I am saying is that the highest spinscan
number can give you the weakest pedal stroke.
Pedalling circles is a different matter, it is the
attempt to apply continuous tangential force to
the pedalling circle throughout the 360 degrees,
the maximum force is around the 3 o’clock area,
this is because the chainring is in a fixed position.
Linear pedalling is the attempt to apply maximum
tangential force to the pedal axle cover from 11 o’c
to 5 o’c, it is possible and gives almost continuous
maximum power application to the chainwheel
throughout its 360 degrees. But linear pedalling
will not give the higher spinscan numbers because
as cadence increases the pedal force decreases and
the unweighting of the rising leg has a greater
effect on overall power application and this takes
place in the 3 o 'c area.
Yeah, mine USED to be too. Also after long runs. Then I got PC’s and my hip flexors don’t limit me near as much now.