RoadBikeReview.com's Forum Archives - Components


Archive Home >> Components(1 2 3 4 5 6 7 8 9 10 )


16% MORE POWER FROM A CRANKSET?(13 posts)

16% MORE POWER FROM A CRANKSET?SDH
Mar 16, 2001 11:20 PM
HAS ANYONE TRIED ROTOR CRANKS? IT'S NEXT GENERATION TO SHIMANO'S BIO PACING. IT'S UCI LEGAL (AS OF OCTOBER 2000) BUT NOT GETTING A LOT OF USE BECAUSE IT'S NOT CAMPY OR SHIMANO (I.E. SPONSORS WON'T ALLOW IT IN RACES). THE INDEPENDENT FEILD TESTS NUMBERS ARE 16% MORE POWER, 15% REDUCTION IN LACTIC ACID PRODUCTION, AND 5% LOWER HEART RATE. DOES ANYONE KNOW OF ANY SHOPS THAT CARRY THEM, AND HOW MUCH THEY COST? I'VE CHECKED ROTORBIKE.COM, BUT ONCE YOU GET PAST THE INTRO, IT'S ALL SPANISH. ANY TRANSLATORS OUT THERE?
It is actually 15.853% (nm)Mick
Mar 17, 2001 2:42 AM
re: 16% MORE POWER FROM A CRANKSET?Spoke Wrench
Mar 17, 2001 6:10 AM
Is that the one with the cam that advances and retards the crank arms as they pass the "dead center" at the top of the stroke? If so, it looks to me like a complicated, expensive and heavy way to do the same thing as an oval or bio-pace chainring. I sometimes think that some people waste way too much time studying and reading books and don't spend enough time riding their bikes.

The issue that led to the demise of the bio-pace chainrings was that they were too cadence sensitive. People who pedal real slowly benefitted from them. The small granny bio-pace rings looked almost square but were about equal to another gear pedaling up a steep hill at about a 30 cadence. Keep in mind that in those days a real low hill climb gear would be about 30 gear-inches so that was a big help for some people. Today, many mountain bikes have hill climb gears below 20 gear inches.

Try to crank the cadence up to 90 or so and they didn't work so well. At that rate momentum will help carry the pedals over the dead spot and the bio-pace induces a choppy pedaling motion that kills the smooth stroke that is required to maintain a high cadence. Shimano tried to cure the problem by making the bigger bio-pace rings progressively less oval, but finally went back to round.

Assuming they are what I think they are, I doubt Rotor Cranks would be much benefit to enthusiast-level bike riders. Printing their claims in all caps doesn't make them any more valid just harder to read.
horse dungJack S
Mar 17, 2001 6:35 AM
nm
nice adDaveG
Mar 17, 2001 3:13 PM
You didn't seem to have too much trouble translating that data for your post. I have to admit the rotorbike.com website intro is really cool, even if its all BS.
Here's how you do itKerry Irons
Mar 17, 2001 3:19 PM
To get 16% more power, you have to apply 16% more pedal pressure at the same crank length and cadence, pedal 16% faster with the same pedal pressure and crank length, or use a 16% longer crank with the same pedal pressure and cadence. Sorry, but that's the only way you can get 16% more power. Given that a drive train is about 98% efficient there is no physical way to get more power out of a drive train without putting more power in. And so far, no one has EVER made one of these miracle crank/chainwheel systems that delivers on this kind of TOTAL BS claim.
Here's how you do itSDH
Mar 17, 2001 9:19 PM
I AGREE WITH EVERYTHING YOU SAID, AND I'M NOT SAYING THAT I AM BLINDLY BUYING INTO THE NUMBERS. HOWEVER, IF THE CRANK COULD PLACE THE LEG IN A BIOMECHANICALLY FAVORABLE POSITION FOR A GREATER PERCENTAGE OF THE ENTIRE CRANK CYCLE, WOULDN'T YOU THEORETICALLY BE ABLE TO APPLY MORE PEDAL PRESSURE? I ALSO READ IN A DIFFERENT ARTICLE THAT TEAM ONCE DID WANT TO USE THE CRANK, BUT WAS NOT ALLOWED BY SPONSORS. IT CAN'T BE TOTAL BS, CAN IT? REFERRING TO SPOKE WRENCHES REPLY, I THINK THE KEY WEAKNESS WITH THE CRANK WOULD ARISE WITH HIGHER CADENCES, WHERE THE STROKE WOULD GET CHOPPY.

THANKS FOR THE FEEDBACK.
Why are you yelling???nm
Mar 18, 2001 8:57 AM
I agree, in theoryDog
Mar 18, 2001 3:45 PM
The round chainring has dead spots at 12 and 6 o'clock, and doesn't produce much power on the up stroke. In theory, if you could apply power more evenly throughout the pedal circle, you might produce more power with the same effort.

At higher cadences, though, the deadspots are less pronounced. Therefore, many cyclists train to pedal higher cadences.

This may be a good idea for beginner or casual recreational cyclists, who never attempt to "pedal circles" or spin at 110 rpm's for long distances.

Now, if they could make the "biopace" effect variable with rpm, and still keep it reliable, light, and relatively friction free, you might have something.

Doug

P.S. Typing IN ALL CAPS is considered annoying by many.
sorry.sdh
Mar 18, 2001 4:23 PM
three different negative comments about the all caps -- sorry folks. i have a background in graphic design and should know better, but i also am a two finger typer and get lazy with the shift key. however, i know when to suck it up and admit defeat. please, i am done incurring your wrath, both in terms of defending this ridiculous crank, and using all caps. i'll work on using more hip flexor in my stroke, and more thumb in my type. thanks for the roasting, and put a fork in me.
Good topic, thoughDog
Mar 18, 2001 8:59 PM
Actually, I think most of us enjoy hearing about new stuff; also, many of us could be wrong - we tend to go on gut feelings from past experience, but possibly haven't considered something. Nonetheless, debate is always good.

The caps thing is sort of internet wide. Just sort of a no-no. No big deal, really.

If you see anything more about this crank thing, I'd like to read it. Thanks.

Doug
If you're interested...sdh
Mar 18, 2001 10:12 PM
Actually, I gleaned most of my info from an article by David Diaz Blanco posted on totalbike.com. The author seems to have some experience using them.
re: everything old is new againAkirasho
Mar 23, 2001 10:35 PM
... found this link residing on Sheldon's site.

http://www.cyclesdeoro.com/PMP_main.htm

... who knows what the future holds...

Be the bike.