Sastre's chainrings

chriskempton
chriskempton Posts: 1,245
edited August 2008 in Pro race
Was I imagining it, or was Sastre riding oval chainrings in the final TT? I thought these were history after Shimano's Bio Pace efforts in the early 90s?

Comments

  • method
    method Posts: 784
    He was using Rotor Rings, they are oval and fairly popular these days. Very different to bio-pace though.
  • andrewgturnbull
    andrewgturnbull Posts: 3,861
    method wrote:
    He was using Rotor Rings, they are oval and fairly popular these days. Very different to bio-pace though.

    Well, just the same but rotated 90 degrees.

    Cheers, Andy
    http://www.andyturnbull.co.uk
    http://www.stirlingtri.co.uk
  • method
    method Posts: 784
    andrewgturnbull wrote:
    method wrote:
    He was using Rotor Rings, they are oval and fairly popular these days. Very different to bio-pace though.

    Well, just the same but rotated 90 degrees.

    Cheers, Andy

    Q-Rings are elliptical the other is asymmetrical. Having used both they feel very different to ride. Although on the whole I'll stick to round ones.
  • andrewgturnbull
    andrewgturnbull Posts: 3,861
    method wrote:
    andrewgturnbull wrote:
    method wrote:
    He was using Rotor Rings, they are oval and fairly popular these days. Very different to bio-pace though.

    Well, just the same but rotated 90 degrees.

    Cheers, Andy

    Q-Rings are elliptical the other is asymmetrical. Having used both they feel very different to ride. Although on the whole I'll stick to round ones.

    Hi there.

    Sorry you'll have to explain that to me... Are q-rings oval or elliptical?

    Bio-pace (I've still got a set in my loft...) were elliptical in such a way as to reduce the the effective diameter of the chain ring at top-dead centre. I though the ones Sastre, Julich etc were using were the same, but rotated around so that the effective diameter is increased just after top-dead-centre?

    Cheers, Andy
    http://www.andyturnbull.co.uk
    http://www.stirlingtri.co.uk
  • method
    method Posts: 784
    Not entirely sure Andy, according to the website they are elliptical, but biopace were asymmetrical, I'm not sure what the difference is.

    All I know is that with Q-rings the the diameter of the chain ring is at its smallest in the dead spot, supposedly to get you though it quicker. Whereas with biopace they had the maximum equivalent tooth size in the dead spot.
  • Evil_Cod
    Evil_Cod Posts: 35
    I'm missing something- why use them? Would it have given Sastre the advantage in the TT?
  • richa
    richa Posts: 1,631
    Evil_Cod wrote:
    I'm missing something- why use them? Would it have given Sastre the advantage in the TT?
    Supposedly more efficient. In theory, yes.
    Rich
  • andrewgturnbull
    andrewgturnbull Posts: 3,861
    Hi there.

    There's a thread over on the tech bit of the forum with some more chat (though not necessarily any more information).

    http://www.bikeradar.com/forum/viewtopic.php?t=12579196

    Cheers, Andy

    ps Rich - More efficient? Who's theory is that? Or is it marketing?
    http://www.andyturnbull.co.uk
    http://www.stirlingtri.co.uk
  • redbicycle
    redbicycle Posts: 271
    supposedly a bit more efficient. Julich has been using them for several years now and I suspect he turned Sastre on to them...or, maybe not. Rotor Q is a Spanish outfit I believe (at least they're manufactured there).
  • Evil_Cod
    Evil_Cod Posts: 35
    redbicycle wrote:
    supposedly a bit more efficient. Julich has been using them for several years now and I suspect he turned Sastre on to them...or, maybe not. Rotor Q is a Spanish outfit I believe (at least they're manufactured there).

    I thought those two didn't get along :?
  • method
    method Posts: 784
    Shimano bought the patent from Rotor last year some time and are supposedly bring out their own in 2009. I think I've seen something like 10 watts increase claimed, quite a bit of anecdotal evidence to back it up, not seen a proper test done though.
  • chriskempton
    chriskempton Posts: 1,245
    Their website claims tests showing 3% more efficient (lower HR at same speed). The rings are supposed to give an effective lower gear over top dead centre and bottom centre to make it easier to get through the ergonomically harder phases of the crank revolution. At these bits, a 53 chainring has the equivalent gearing of a 51 tooth ring. At the (cranks level) naturally easiest section of the revolution, the effective gearing is equivalent to 56 ring.

    Sounds reasonable, but surely the cost in front mech performance must be pretty high.
  • ride_whenever
    ride_whenever Posts: 13,279
    but if they make fat ones it'd be perfect for singlespeeds, you'd be able to gurn up slightly steeper hills
    Neeermad
    Carbon 456
    456 lefty
    Pompino
    White Inbred
  • andrew_s
    andrew_s Posts: 2,511
    method wrote:
    Shimano bought the patent from Rotor last year some time and are supposedly bring out their own in 2009. I think I've seen something like 10 watts increase claimed, quite a bit of anecdotal evidence to back it up, not seen a proper test done though.
    What patent? Considering that oval chainrings have been in occasional use for over 100 years, I wouldn't have thought that there any unused shapes left to be patented.

    You want to take headline power increase figures with a pinch of salt too. It will depend a lot on what the cadence is, and if it's 10W/3% extra at 40rpm, it won't help all that much in general riding. If there was any great advantage surely everyone would be using oval rings by now, considering how often they've been tried.
  • method
    method Posts: 784
    andrew_s wrote:
    method wrote:
    Shimano bought the patent from Rotor last year some time and are supposedly bring out their own in 2009. I think I've seen something like 10 watts increase claimed, quite a bit of anecdotal evidence to back it up, not seen a proper test done though.
    What patent? Considering that oval chainrings have been in occasional use for over 100 years, I wouldn't have thought that there any unused shapes left to be patented.

    You want to take headline power increase figures with a pinch of salt too. It will depend a lot on what the cadence is, and if it's 10W/3% extra at 40rpm, it won't help all that much in general riding. If there was any great advantage surely everyone would be using oval rings by now, considering how often they've been tried.

    No idea on the patent, just quoting a post from Weightweenies last year.

    As to wheather they work or not, I wasn't suggesting the evidence was valid, I said it was anecdotal. As to why everyone doesn't use them, I guess this is because they may not suit everyone.

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