KOPs how do u measure?

[mercalia]

do u put the plumb line at front of knee or at centre where the pivot would be. I have had a look at a few of the articles here, not sure if any say, one did say measured from the front of knee. I would think it would make a big difference?

[NATURAL ANKLING]

Hi,
Front of the knee.
ColinXXX will give us a picture.
Just remember to set your seat hieght last.

[honesty]

I used my daughters skipping rope...

measurement was from the knobbly bit underneath the kneecap.

[531colin]

I used my daughters skipping rope...

measurement was from the knobbly bit underneath the kneecap.

The tibial tubercule, no less (relative of Hercule Poirot, perhaps?)
http://forum.ctc.org.uk/viewtopic.php?f=5&t=74985

[Ayesha]

Are you going to TimeTrial, road race, tour or 'beach cruise'?

[mercalia]

just slow touring. Thought I would take a new look & see if I could improve as now getting on a bit and expectations have changed. eg I used to think the gears on my 1-Down were very low, now seem about right, in fact better than I can give lol.

[rgc_911]

given the almost infinite variation in the human form, and certainly variations in thigh, shin , leg and torsos, why would this ever be a meaningful measurement?

http://sheldonbrown.com/kops.html

[Brucey]

I know it is popular to knock the idea of KOPS and say it is a myth etc but I reckon the knockers may have not given the matter quite enough thought.

To get KOPS you need the the saddle height and the saddle setback to be within a certain range. I've always set the saddle height first, and then used KOPS to see that the saddle setback is sensible. IME this gets everything right within about 1cm for most riders who want to be riding the bike without crippling pain for hours on end. If the saddle has adjustment remaining fore and aft, up and down by 1cm or so then you can be 99.9% sure that the bike is a good fit in terms of saddle position. I don't know of any other means of determining this as quickly, or obtaining a good 'base' for setting up a good riding position, and makes allowances for variations in C/J ratio.

So why might it be valid?

Well most of the power appears to be developed in the part of the pedal stroke between about 2 o'clock and 6 o'clock. Not a big stretch to suppose that the angles in the leg are important during this phase. Most folk agree that the angle in the knee joint at 6 o'clock is important. This places the knee in a fixed position wrt the pedal spindle at 6 o'clock which as it happens is also not a million miles away from being immediately above it. If this is the case and you also get 3 o'clock KOPS (at the same ankle articulation), then this means that the average angle of the thigh to the ground in (the 3 o'clock to 6 o'clock part of) the power stroke is a constant, around 45 degrees. Now this may not automatically result in pedalling perfection, but I think this may well be fundamentally biomechanically significant.

Rightly or wrongly, coincidence or not, I don't recall seeing very many cyclists (barring some competition riders in extreme aero positions whose comfort would be debatable...) who rode swiftly in relative comfort who were not within a cm or so of KOPS.

cheers

[531colin]

....and is there another way to set up your saddle that is as simple to do, as easy to explain, and better?

....because if there isn't, I don't see any point in rubbishing KOPS

[PH]

given the almost infinite variation in the human form, and certainly variations in thigh, shin , leg and torsos, why would this ever be a meaningful measurement?

http://sheldonbrown.com/kops.html

With the whole of the internet to choose from, why is it always the same article linked to rubbish it?
It's a good starting point that works for most people.

[Jezrant]

I notice that no one has addressed Bontrager's issues.

I can suggest a simpler way to set up the saddle that works every time perfectly. Set the fore/aft so that the saddle is in the middle of the rails (Brooks included). This is the starting point, rather than KOPS. Now go out and ride the bike a few times, and adjust as necessary. It may be take several rides to find the right fore/aft for yourself. Take an allen key or whatever spanner you need to make any needed adjustments while out on the ride.

What's wrong with that method? *

*Edited for compliance with Health and Safety Reg. AZ3947/B12r95:
Please be aware that by using this method there is a risk of causing lasting and irreversible bodily harm that may only become apparent many years later.

[Brucey]

...What's wrong with that method?

It presupposes that your physique is suited to your seat angle/saddle/seatpin layback combination.

IME it probably won't be.

Biomechanically you are letting your bike geometry determine your body position rather than the other way round.

cheers

[Jezrant]

Yes, it's true, there are a number of assumptions, but IME it works better than KOPS. It just takes more time to finetune, and unfortunately it can't be done in a fitting session in a bike shop.

[Brucey]

in a good number of cases you can't get a good setup this way at all, and you only get to find out once you have bought the bike. It is not a good technique unless you are;

a) able to set yourself up properly this way (which most people can't) and are

b) also happy to go through badly fitting bikes which you then have to sell on.

Saddle height + KOPS has quite a lot going for it really. What you propose doesn't address anyone's critcisms of KOPs and is arguably little better than guesswork.

I've had to beg some of my cycling buddies to let me alter their 'homegrown' position which they have used for years. They complain that their back hurts, knees hurt, shoulders hurt etc. and I can see it is their riding position clear as day, but they often won't change things 'ooh it took me ages to get set up right..'. etc. I have even had to record their crummy position in meticulous detail on the basis that they might want to revert to it having tried something different. Not that they do; once set up properly (using quite simple techniques, not guesswork) they never choose to go back again, because they are more comfortable and go better. If you can acheive a good position by trial and error, starting with something accidental, fine, go ahead; but if you do it like that and do it properly you are one in a million...

cheers

[RickH]

Just checked on the 2 bikes parked in the house - my main road bike (Kinesis Tk frame) & my old MTB (1986 vintage Muddy Fox awaiting fitting of winter marathons for when we get snow & ice) - lining up the BBs the top of the seatpost of the Muddy Fox is about 1cm further back than the Kinesis. But, guess what, the saddle is about 1cm further forward in the clamp.

Once you've set up the saddle by KOPs (or indeed any other method) on 1 bike, if you measure the top of pedal to top of sadde along the line of the seat tube & the distance the nose of the saddle is horizontally from the BB centre you can set up almost any bike, assuming the crank length is the same, from those 2 measurements. (I do say 'almost any' as it won't quite work with the stoker's seat on the Circle tandem, as the rear BB is behind the bottom of the seatpost! But I haven't seen that anywhere else before.)

Rick.