Knee over pedal spindle...discuss

Discussion in 'Bicycle Mechanics and Repairs' started by Fiona N, 14 Apr 2010.

  1. Fiona N

    Fiona N Veteran

    I've just been down to Paul Hewitt's in Leyland for a bike fitting before shelling out for a new road bike and he uses the 'knee over pedal spindle' (K-o-p-s) fitting parameter (for want of a better term). I've been with Mike Burrows on this i.e. what's special about vertically above the pedal axle on the level when as soon as you start to climb a hill, you'll be tilted back thus the knee will no longer be vertically over the pedal spindle and, after all, it's going up hill when you're likely to want every watt you can muster. And why do climbers move back on their saddle when climbing which moves the knee even further behind the pedal? And how do you explain what we do on recumbents?

    Anyway, with a fit which included k-o-p-s, there's a noticeable difference when pedalling (and this was just on the jig) compared to my current set-up, which was what you might call 'ad-hoc', i.e. bits from another bike (frame kaput) onto a new cheap frame et voila - a new road bike ;). So it's going to be interesting to see how/whether this translates into more power on the hills on the new bike.

    Does anyone else have strong feelings about k-o-p-s?
     
  2. GrumpyGregry

    GrumpyGregry Here for rides.

    My fave dismantling of the myth

    kops probably makes a good starting place. kops probably sells a lot of seatposts. bodies adapt.
     
  3. dave r

    dave r Dunking Diddy Dave Pedalling Pensioner

    Location:
    Holbrooks Coventry
    I have tried that in the past. I just pedalled harder and went slower, I changed it back after just one trip.
     
  4. GrahamG

    GrahamG Veteran

    Location:
    Bristol
    It's a reasonable starting point - I've got a hewitt custom frame after a fitting - but I find myself more comfortable at about 10mm further back from the proper 'kops' measurement. Bar height/reach were more of a revelation than my saddle position which I'd had pretty well tuned.
     
  5. MartinC

    MartinC Über Member

    Location:
    Cheltenham
    I've got no strong feelings about kops And I don't really understand why some folks rail against - or why others think it's so important. To me it's probably a good first approximation of saddle setback that you can make without measuring anything.

    For me saddle setback is one of the key parts of postioning but not whether it's kops or not. It will change depending on the type of riding you do too.

    Many years ago I spent a wet Sunday afternoon measuring myself and using Bernard Hinault's position calculations to derive my ideal postion. I tried it and it worked for me so I've used the measurements ever since. This put my saddle further back than I used to have it and it was an immediate improvement. Hinault's method uses your body proportions to derive the saddle setback from the BB.

    Incidentally, your bike position is all about the relationship between the 3 sets of contact points with the bike - saddle, pedals and bars. Whether you're uphill, downhill or on the flat this doesn't change although your weight distribution might
     
  6. ChrisKH

    ChrisKH Veteran

    Location:
    Essex

    Got any further info. on the Hinault method MartinC, or where we might find it?
     
  7. snailracer

    snailracer Über Member

    When your legs have turned to jelly from exhaustion, KOPS stops your feet from sliding off the pedals!
     
  8. GrumpyGregry

    GrumpyGregry Here for rides.

    surely that is what spds are for?
     
  9. jimboalee

    jimboalee New Member

    Location:
    Solihull
    Which part of the knee?

    The very front or the little protruberance on the side?

    What pedalling style do you employ?
     
  10. MacB

    MacB Lover of things that come in 3's

    I used the Competitive Fit website and downloaded the results for all 3 styles of fit. My saddle setback range, measuring BB centre to saddle nose was:-

    Competitive - 68-72mm
    Eddy - 80-84mm
    French - 75-79mm

    I actually have 80mm on all 3 bikes and this seems to work well for me, I don't really know where my knee is in relation to the pedal spindle. However the fact that I use flat pedals does mean I can move my feet around. I find that I will slide the foot forward for a long, seated, uphill and I get more on my toes if I'm hammering it.

    I've actually found that I'm using a combination of the Eddy and French fits to get my ideal.
     
  11. e-rider

    e-rider crappy member

    Location:
    South West
    KOPS isn't the flavour of the month these days and is considered a bit old skool! I would say that it's not a bad starting point though. IMO Femur bone length is important but others say that it isn't.

    TTers like to get their knees well forward hence the steep seat tube angles whereas tourers do the opposite. For the rest of us we occupy the space in between.

    By using one of the vast number of seatposts available, from inline to 40mm setback, most people should be able to achieve a good position on most frames if it's generally the correct size in the first place.

    Personal preference plays a big part too, along with riding style and speed.
    If I push my saddle far forward or right back on my current seatpost both positions feel terrible so I can be pretty sure that the correct position is somewhere inbetween - a few more adjustments and test rides and we have the perfect position - no calculations or expensive bike fittings required!
     
  12. accountantpete

    accountantpete Legendary Member

    I turn the cranks as a pedal technique - seat positioning is derived from the feedback coming from the pedals. Seat too far back and you emphasise the pulling up phase in the rotation.Seat too far forward emphasises the pushing down in the rotation. Seat too low overstates pull back instead of push forward.

    I'd rather have my seat position based on feedback from the bike in a manner I understand than rely on the quack seat positioning gurus.
     
  13. snailracer

    snailracer Über Member

    When your legs have turned to jelly from exhaustion, KOPS stops your feet from sliding off the pedals!

    You'll want to be unclipped before you topple over from exhaustion :wacko:
     
  14. MartinC

    MartinC Über Member

    Location:
    Cheltenham
    Hinault published a book in the 80's with a detailed explanation of how to calculate your position. At work at the moment so haven't got the ISBN. IIRC it's "Road Racing" by Hinault and Genzling.
     
  15. GrumpyGregry

    GrumpyGregry Here for rides.

    out of print but available used from the usual suspects
     
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