Offset Bike Cranks, Tour De France Here I Come


2282_20080574206.jpgBy Bruce Eaton

Now I am ready to truly give Lance Armstrong a run for his money with the Rotor Crank System. Designed by someone who is, presumably, smart, the Rotor Crank does what all cyclists wish their pedals did for them: remove that dead spot at the top of a new stroke. Well, this system does just that by using two independent cranks which work together to make sure the pedals never end up in a 180 degree alignment with each other. You end up with no dead spot and always in a power stroke. No more jamming your knees, injuries to tendons due to that dead spot, and better maintenance of traction as wheels do not slow down and do not have that unnatural jumpiness.

Available at RotorCrankUSA, in steel or titanium. You won’t have to sacrifice weight to add this on as there are plenty of options to get this system on your bike. But due to pricing ranging from $693 for a double steel road set to $963 for triple titanium road set, you will sacrifice your wallet, bank account, kidneys, something. But for a semi-pro to very hardcore rider, this seems worth the investment.

[Rotor Crank] VIA [Gizmag]

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A graduate of Colgate University, Bruce is one of the elite Henro or pilgrims who have completed the 900 mile 88 Temple Pilgrimage on the island of Shikoku, Japan by means of foot power, a feat (no pun intended.... ok maybe alittle) which is no laughing matter. He not only finished this task with a crippling leg injury but he has attained enlightenment according to the monks on Koyasan. Currently the 23 year old is living in San Antonio where he spends his time working as a Data Analyst but also trying to accomplish his next great challenge, drinking all 200 beers at the Flying Saucer. Having recently married his long time friend from college and seen as nuts for doing so, Bruce relishes his life and hot dogs generously. KANPAI!!


  1. Clips still slow you down when one pedal is at the top and the other is at the bottom. These presumably keep the speed uniform the entire time.

  2. I can’t see this being good for your hips.
    And if this thing is so good why haven’t we seen it at the Tour De Frangce (or other large race). For my money i’ll get a set of powercranks and train the dead spots out of my stroke (and they cost about the same) see

  3. Biomechanics researchers will have fun with this one. Cyclists won’t, ever think of a problem due to muscular imbalance initiated by more work on one side vs. the other. One leg will become overused. Hip problems will also result, IT band issues, who knows what else.

  4. Scratch my comment, I thought the arms were fixed. Having continuously adaptable arms is much better. It also gets rid of muscular imbalance. One thing to not however is that the dead spot does provide a momentary rest period for the legs. Presumably, inegrating the rotary crank with training would reduce the need for that rest?

    I’ll try ’em. Anyone want to donate?

  5. doesn’t this just change the deadspot from the top of the cycle to the period when the crank arm is changing from upright to bent?
    e.g. there is a time when you are moving the crank but not putting any effort into moving the bike.
    not to mention this isn’t a new product (I first saw it well over a year ago) and it is neglecting the entire use of calf muscles/feet/etc during the stroke. just my two pennies.

  6. The reason you havent seen something like this at the TDF yet is because of traditionalism. Although there is all kinds of new technology flowing through the peleton some things are just hard to break away from, things that have been the same ever since day one. There have been improvements in the spokes of the wheel or the hub, but nothing major, the bars may have flat portions on the drops now, but there are still drops that look essentially like they always have. There have been some pretty radical frame designs but they all still ride a double triangle frame. The TDF is the top race, and most top racers are going to risk using something totally different with A LOT of testing. If this does work it will still likely be a couple years before it shows up in the peleton.

    On a side note, Bobby Julich rides an oval shaped chainring to help try to get rid of the dead spot. You can see a picture of it here:

  7. ^^ Edit

    I stated that most races are going to risk using something totally different with a lot of testing.

    I ment to say that most races are NOT going to risk using something totally different WITHOUT A Lot of testing.

    Sorry about that.

  8. Why does something like this remind me of those weird oval chain-rings that SunTour (I think!?) used to make. Was meant to improve power or something like that, but just ended up being well, dumb…

  9. Shimano had “biopace” or oval chainrings back in the late 80’s and they didn’t stick for the simple reason that it is very difficult to maintain a spinning rhythm.

  10. This is a stupid marketing gimmick. One dead spot is removed and the other one is enlarged. Think about it! What happens when you get to the bottom stroke on the bent petal and the straight one is still 5 degrees from top?

  11. might be better for a kids bike where kids get stuck in the dead spot and not able to crank back due to the foot brake. (Overloading the brake function on to the pedal is common for kids bikes)

  12. While i can’t comment on how useful these may be, it seems many people don’t understand that there’s a pivoting arm there – they’re not ‘locked’ as you see in the image..

    So no ‘larger’ dead spot is created..tho i do gotta wonder what it’s like to have a ‘loose’ crank arm like that..!

  13. I still don’t think that people understand how this is supposed to work. One arm is not offset from the other. As the crank is turned the rising pedal travels faster than the pedal being pushed down. In other words, as the pedal being pushed down travels 180 degrees, the rising pedal travels 185 degrees.

  14. Shimano and others experimented with Oval cranks to more evenly distribute the force required to turn the crank around the circle. They sucked. The fact is, any sense of asymmetry in the stroke kills the fluidity which is crucial to efficient pedaling. Can you use this design in a 2 stroke engine? No! The asymmetry would tear it apart. It’ll do the same to a man.
    A beginners’ Guide to Portland, OR

  15. From the summary: “Well, this system does just that by using two independent cranks which work together to make sure the pedals never end up in a 180 degree alignment with each other. You end up with no dead spot and always in a power stroke.”

    This is no marketing gimmick, as Dave and wrap already said, the rising pedal moves faster than the one being pushed down so it is ahead of the bottom pedal when it is directly at the bottom. This thing is pretty amazing, although expensive :/

  16. Chris:

    1. They have been used in the tour de france, by a spanish team.

    2. You’re certainly right that you will get far more benefit from training your stroke.

  17. There is no dead spot in my pedal stroke. It is an even dispersion of power in a circle. I think of it as a triangle, but in actuality it is a circle. I can’t imagine anyone wanting this.

  18. What it looks like many of you don’t understand is that the dead spot is when you are not pushing down with any leg. This system makes sure that at least one leg is able to push a pedal, therefore you don’t have to wait for one of them to get a pushable angle. You will always be able to push one of them and you will be able to keep the pedals rotating with as little flaws as possible. Try stand while cycling and see what you feel when they have a 180 degree angle vertically. It’s something like that this system tries to remove.

  19. Just because traditional cranks can exist in a vertical alignment doesn’t mean they’re “dead”. I see these as allowing an untrained piston stroke to gain some of the advantage of a trained stroke.

    I’d be willing to try them out (I even owned a pair of those Shimano oval cranks), but call me a skeptic. I don’t feel a lull in my round chainring and these look like they’re feel imbalanced.

  20. Shame on me for commenting without really looking into them much. I thought these were cranks that had some “play” to shift the deadspot, but rather they are COMPLETELY independent of each other.

    After watching the demonstration videos, I take back my earlier openness to trying them. Decoupling my legs does not look like a good idea at all. Nor does being forced to pull and push on every stroke on long rides; these would hamper my ability to shift muscle groups.

  21. It seems that most of the people who commented negatively didnt really look into this product before commenting. “Hmm…looks like a set of expensive cranks that have one arm offset from the other. Must suck.” Check out the video from the site and then see if it makes more sense. If you still don’t understand why this is an advantage, then you probably aren’t the type of person who woudl even be interested in a product like this and in that case, why comment at all. Just becuase you don’t understand something doesn’t mean it doesn’t work. [/rant]

  22. how come all the video links in here go to shite?Biopace cranks – those oval things hurt my knees there was a sudden dropout on the downstroke that created problems for me. I was riding eight hours a day at the time

  23. i dont understand how these things work. but screw them, offset cranks… my behind. anyway adults shouldnt be riding bikes. must be gays. unless you lost u license b/c of dui. then i m not mad.

  24. Great – it’s 1985 all over again. It’s interesting that they don’t list the weight on their website… I think I could put the $1000 cost to better use than this crap!

  25. It may “remove” the dreaded dead spot, but as every cyclist should know, don’t fix what isn’t broken, the use of good “ankle-ing” in a perfect pedal stroke already has very little dead spot in it. It would be very cool to try out, but I would rather stick to my fix arms – especially when in the mountains, I like a little leg rest.

  26. I agree that there need to be further studies on this matter, Shimano tried it with Biopace in the late 80’s, there are Rotorcranks, and PowerCranks. Each does something quite unique but I feel that PowerCranks is the most complete system. Why else would Di Luca, Bettini, Hincapie and others such as Magnus be training on them and even use them on their rest days in the Tour or the Giro?

  27. I have a set and they are really for Triathlon and not roadies.

    I ride in B grade at the local bike races and at Ironman have done 5:10 on normal cranks.

    The following year I did 4:50 BUT is was so much fresher getting off the bike to run the 42K.

    Basically what I am getting at is if you are doing 180K or 90 time Trials they are great.

    If you are in a pack you might as well save your money and ride normal cranks. Unless you always plan to do break aways and actually stay away.


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  29. Just been searching for other people’s opinions on RotorCranks and I know this is an old thread… my apologies for bumping it, but I do have an opinion that may be of interest
    I have just recently had 175mm Rotors put on my time trial bike. Recently as in yesterday. I rode for 20minutes on them yesterday, and 41 minutes on them this evening. I like them, I liked them after about 5 minutes. If I likened it to moving by foot… its like you are skiing rather than skating… one solid fluid movement. I climbed the small rises in my big chain ring when on my previous cranks I would usually change into the smaller.
    Down one hill into a flat where on my previous set up I could get up to about 58kph and maintain about 50-55kph for 300metres or so before the next rise, I got up to nearly 63kph and maintain over 56kph on the short flat.
    On false flats where I normally, with effort, bike at around 16-18kph… suddenly I was going no lower than 17.5kph – and i wasn’t even trying hard.
    I’m am impressed. I like them. I am looking forward to my next time trial to try them out in a race situation on a known course.
    I think you have to try them before you judge them…

    And as for why we don’t see rotors in high profile races… ever heard of sponsership? Those boys don’t necessarily ride the best bike or have the best sundry equipment. They ride the gear their sponsers provide for them. Simple as that.