Ultimate saddle Position / KOPS

General cycling advice ( NOT technical ! )
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Witterings
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Ultimate saddle Position / KOPS

Post by Witterings »

I know KOPS is considered a staring point to get your saddle in approximately the right position but what are the differences / benefits between going more Fore / Aft.

Is one generally considered to be better for sprinting vs touring or hills vs flat and I guess overall efficiency combined with comfort is the ultimate goal ... or is it totally down to the individual.

I just moved mine back about 5mm before a ride yesterday and it certainly felt nicer on my rear / undercarriage at the end of the ride but wonder if my legs were more out "in front" and it felt as though I lost a bit of "push down" but guess we want efficiency as a priority as well so maybe one is a trade off against the other.
Samuel D
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Re: Ultimate saddle Position / KOPS

Post by Samuel D »

As you say, KOPS gets the saddle in approximately the right place, but it can mislead you into thinking that that place is important for the pedalling action. I don’t believe it particularly is. Recumbent bicycles often have pedals straight out in front, yet their riders manage to pedal efficiently (after an initial period of adjustment).

But KOPS happens to result in roughly the right weight balance between handlebar and saddle for many riders of upright bicycles. That is its merit.

Adjusting the saddle forward and back has a big effect on weight balance. If you put it back, you reduce weight on the hands; if you put it forward, more weight is thrown onto the hands. Small adjustments make a large difference to weight on the hands, even though they can be barely detected in the pedalling action.

Most seatpost clamp designs require a slight adjustment to saddle height after moving the saddle forward or backward, to keep your knee extension at the ‘bottom’ of the pedal stroke the same.
amediasatex
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Re: Ultimate saddle Position / KOPS

Post by amediasatex »

There are some loose guidelines/rules but as with all rules there are always exceptions so personal preferences and quirks of anatomy and riding style can play just as big a part. KOPS is nothing more than a coincidental starting point that happens to apply for the majority of conventional upright bicycles. As soon as you deviate from there by intent or anatomy then KOPS falls apart.

I don't use the same setback on all my bikes, in general my longer distance bikes and comfort oriented bikes have a more rearward bias, and my 'fast and furious' bikes are a little more forward. There's a lot more to it than that with other position changes between them in terms of drop and reach as well, and differences in the geometry that come into play too, but in general the above holds true for me, and on both types I favour more setback than seems to be the norm and I disagree quite strongly with one of the local 'formula fitters' on what my ideal positions are for various bike types.

That's not to say you can't ride fast with a lot of setback, or that you can't ride in comfort with a forward position, but there are effects that are apparent with different positions and to be honest the only way you can really appreciate them is to actually ride (and adjust to) different setups and get a feel for how they differ and what does or doesn't work for you. A lot will depend on your riding style and the kind of rider you are too, ie: spinner vs masher, your flexibility, seated vs standing, steady speed or lots of changes etc.

Colin has written a very informative guide on general bike fitting and it is well worth a read, it's been linked to over and over again on this forum so should be easy enough to find and is a great place to start, but a bit of experimentation yourself is a really good way to get a feel for how different changes can have different effects.
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531colin
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Re: Ultimate saddle Position / KOPS

Post by 531colin »

Read this https://www.stevehoggbikefitting.com/bikefit/2011/05/seat-set-back-for-road-bikes/
in conjunction with this https://www.stevehoggbikefitting.com/bikefit/2011/02/seat-height-how-hard-can-it-be/

My DIY bike fitting guide (linked below) is simpler but with correspondingly less discussion and explanation.
When you press down on the pedals, the "equal and opposite reaction" of Newtonian physics is an upward force that tends to support your torso. It follows that on bikes where you pedal hard a lot, the saddle may well end up further forward than a similar bike where you don't pedal as hard, or as often.
althebike
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Re: Ultimate saddle Position / KOPS

Post by althebike »

I had a bike fit years ago the specialised big fit, but last year, after a number of sores, I had another fit by a local man, who also did pressure mapping. As a result my saddle was moved as far forward as it would go, I am no longer stretched out in a 1960s racing position ( his words not mine) The result was more comfort by not perching on the nose of the saddle ( I did not even know I was doing this) I sit in a more upright position .I had a lot of tension in my shoulders and my neck ached on longer rides, this has all gone too. So moving my saddle forward was not about peddling action at all. I suppose I could have had the same result by using a shorter stem.
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horizon
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Re: Ultimate saddle Position / KOPS

Post by horizon »

althebike wrote:I suppose I could have had the same result by using a shorter stem.


No, you should have got the same result by using a shorter stem. That way you wouldn't have affected your sitting position (unless of course that was what was needed).
When the pestilence strikes from the East, go far and breathe the cold air deeply. Ignore the sage, stay not indoors. Ho Ri Zon 12th Century Chinese philosopher
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531colin
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Re: Ultimate saddle Position / KOPS

Post by 531colin »

If your bike set-up has too long a reach, you can find yourself dragged forwards and sitting on the nose of the saddle.
Conversely, if my saddle is in its usual position but the reach is too short, I find myself sitting off the back of the saddle.
Saddle position (front to back) isn't really about pedalling, its about your balance on the bike. Saddle height (or at least, knee extension) is about pedalling efficiency.
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