powercranks

[LarryOz]

Has anyone on this forum ever personally used powercranks before?
I have searched the Cruzbike forum posts and only saw one mention of it in the "short crank arms" post, and only mentioned because they have adjustable crank lengths.
The company website is: www.powercranks.com
From reading through all their information, their primary purposed is to train a cyclist to apply constant pressure on the pedals during the entire revolution. It is supposed to increase pedaling efficiency.
Apparently there is some kind of internal clutch (or other) mechanism that dis-engages the right and left crank arms if force is removed at any point during either crank rotation. Once force is constant again, they lock back into their proper position.
I have watched several videos of it in action. It is very interesting to see one crank suddenly drop off!
There are some very convincing testimonies from pro level athletes who saw significant improvement. (of course, they would put a negative testimony on their site, would they?!)
Many of their models alsohave adjustable crank lengths as well. I for one am a believer in shorter.crank lengths, and will continue to experiment to try and find an optimal length for my leg configuration.
I am always looking for ways to improve, so am considering purchasing a set.
Not if this is good or bad, but there are very few used sets out there for sale.
I have search ebay, craigslist, etc. There are some, but most are with fixed or very small adjustable range crank lengths in the 170mm range.
I am looking for the set that is adjustable from 90 to 150 or range.
Thanks in advance for any feedback.

 

[KiwiGuy]

My experience with Powercranks

Hi Larry

I bought a set of Powercranks for my son, Matt, about 5 years ago (the X-lite with dual-mode). He was a very competitive road cyclist as a teenager and these seemed like a useful training tool.

Because we both have our bikes set up on indoor trainers in the garage, I often use the Powercranks as a warm-up before doing a indoor trainer workout on my recumbent. So I'll discuss my observations re Matt and then my own experience.

Pre-Powercranks it was easy to spot Matt in a bunch from more than 500 metres away. He was the guy whose whole body was bobbing up and down. Great for a parent on the side of the rode hoping to get a glimpse of his son flashing by. Not so good from an efficiency point of view. Within weeks of moving to Powercranks the bobbing disappeared. I am left with the strong impression that his cycling efficiency improved substantially. He achieved some impressive results during this time and became part of the BikeNZ Road Junior Development Programme. However, I can't say he wouldn't have achieved the same results anyway - his cousin (my wife's twin sister's son) is a pro cyclist on the Garmin Sharp/Cannondale Garmin team, so there are some good cycling genes swirling around the family.

Matt took to Powercranks easily and did all his rides on them, though he locked them up for racing. During his second year of under 19 racing he was aiming to be selected to ride for New Zealand, but was unfortunately over-trained by his coach. After he recovered, he decided to focus on his University studies and hasn't now raced for the past three years. But having just completed his BCom degree, is now training heavily again. I mention this because he is in the early stages of getting back into constant training, and can only do 45 minutes on the Powercranks before he has to lock them up. Consequently, if you buy a set of Powercranks, I recommend getting the dual-mode so that you can lock them up when necessary.

I have also used the Powercranks and I can tell you this - they are hard work initially. They primarily work your hip flexors and very quickly highlight discrepancies in your pedaling. Even just warming up on them is beneficial as the smoother pedaling for 10 minutes seems to transfer over to using fixed cranks on the recumbent for the rest of the workout.

I fully believe the claims that Powercranks improve your cycling efficiency. They force you to pedal a full circle and bring into play muscles that you don't normally use - particularly your hip flexors, and to some extent your hamstrings.

I also believe the claims that they improve your power output, though maybe not in the way you think. Your hip flexors are pretty small muscles, so the extra recruitment is not going to add much power. However, most people effectively rest their foot (and therefore their leg) on the returning pedal. Work out the weight of each of your legs - they're pretty heavy. By forcing other muscles to effectively get the returning leg out of the way, the power that used to go into pushing that leg up now goes through to the drive wheel.

IMHO Powercranks are a great training tool, but they do have their downsides. They are ugly as. If you want to run a power meter on the crank, you are out of luck (probably need to run a Powertap). And they hurt. Until you fully train your hip flexors, they are hard, painful work.

Hope this helps...

 

[KiwiGuy]

Additional food for thought

Hey Larry

I started a thread on BROL almost three years ago about Powercranks. You can find it here> http://www.bentrideronline.com/messageboard/showthread.php?t=90643

I recommend that you pay particular attention to Robert Chung's comments in that thread.

One of the links he gave is of particular interest - http://james-p-smith.blogspot.co.nz/2009_08_01_archive.html

Having re-read these posts, I still view them as a great training tool. In particular, two or three days a week for 30 minutes as either a warm-up or part of an indoor trainer session. The problem with that approach, however, is that you either need two bikes, or you have to put up with the ugly things on your main ride 24/7. I'm fortunate in that I have access to a second bike (albeit a df) with the Powercranks attached).

Kind regards...

 

[LarryOz]

Thanks for the advice and links

Blair,
It is so good to have "real" feedback from someone who rode on them.
I actually searched over on BROL and found the thread and reference to Chung.
I am split at this point:
Partly because I use Garmin Vector pedals and the only version I can used is their lower one that you can't lockout, and is either fixed length or 20mm graduate from 90 t0 150.
Partly because after an entire year Chung did not really report any increase in power.
Partly because I feel I already have a fairly efficient pedaling stroke (thanks to vector pedals and their :"efficiency readout.) Not saying I am perfect, from it, but I know I do a lot of pulling towards me when I pedal, and do put considerable effort in trying to apply force all the way around my stroke)
Partly because they are so expensive. If I could pick up a pair for $200-$300 I might be wlling to try them, but even then reading up on them, they take a considerable commitment, so ???

Curious with you; not sure how much you ride or rode the DF while you where also riding the recumbent, but did you notice any issues bouncing back and forth from one to the other.
I am a little concerned with getting on my DF at all. I have not been riding a Cruzbike for long, but I know and have read they work different muscles in different ways, and you almost have to re-train them to get efficient with them. Some report it may take 2 years to fully adjust to the position you must sit in while apply power to the pedals.

Heck, I even noticed a significant difference when I switch from an S2.0 to a V20. I put 4+K miles on my S and I think was just starting to get the hang of really applying the power to the pedals laying back at 28 degrees. Switched to the V, and felt am immediate loss in appliable power at the new recline of 20 degrees. Due to the weather and other time considerations I have not been able to ride nearly the miles on the V yes, so only time will tell.

Thanks again for the feedback.

 

[KiwiGuy]

More thoughts and observations

Hi Larry

The evidence is definitely conflicting regarding Powercranks. In addition, I suspect that the advantage is likely to be less on a recumbent. On a df, you are more or less lifting your leg vertically, so unweighting is a big advantage, On a recumbent, you are more or less moving your leg horizontally, so I expect less benefit apart from smoothing your pedaling stroke. Consequently I think it is hard to justify the expenditure, particularly given the feedback you are getting from your power meter on your efficiency - very neat thing.

One way to work on pedaling smoothness without Powercranks (which you've no doubt considered) is one-leg pedaling on an indoor trainer - at end of the warm-up and before you get into your interval sets. I favour 3 mins per leg, 50 rpm, big gear with extension as hard as possible, then 3 mins per leg at 70 to 80 rpm, low gear, and then 3 mins per leg again at 50 rrpm, big gear with extension as hard as possible.

As for switching between recumbent and df. I rode dfs up until 9 years ago and then went fully recumbent for three years. Late 2008 I bought a Specialized Roubaix and rode it for two years but kept on having issues when I increased the miles (saddle sores) or the effort (lower back pain). Consequently, I swopped back and forward between the df and the recumbent for two years before fully committing to the recumbent again.

My experience was that swopping back and forward was very straightforward, but as you've experienced, the longer I was on one platform the better I performed on that, with a slight degradation in performance on the other platform. However, I didn't find the difference to be large.

Kind regards...

 

[mzweili]

Torq measurements

Could this unit be used to measure peddle input??