I was just wondering how modern frame geometry, in particular steeper seat angles affects the KOPS theory ?

I am one of those that has always had my knee slighlty behind the pedal spindle to feel comfortbale but Im finding its quite hard to achieve on newer frames with steeper seat angles.I have to have alayback post and the seat near enough all the way back on the rails.

A bigger frame wouldnt help as the seat angle is the same? is that ocrrect?

So, how do you have your knee? Infront or behind and how does it affect your position on the bike.

It would be interesting to hear from the likes of Brant or Ben pinnick on this as frame designers themselves.

KOPS is a guide at best. Modern frame design seems to make sensible fits easier than ever rather than the other way around. Some STA’s have been horribly slack until fairly recently, especially on long travel full sus frames. Something doesn’t sound right if you have a layback post and the saddle as far back on the rails as possible and still not be quite happy. Crank length? Cleat/ foot position? Maybe you don’t need to be as far back as you think? What are you basing this on?

Should i still be aiming for KOPS or just forget about it?

I find if I am to far forward of the spindle I get muscle pain in the muscle just sbove my knee.

Is this lack of use or just wrong though?

Cos you can never post enough good Keith Bontrager thinking. Its been around for a while, but I don’t think development in bike fitting has done anything to make KOPS more appropriate.

The myth of KOPS

“The KOPS rule of thumb has no biomechanical basis at all. It is, at best, a coincidental relationship that puts the rider somewhere near his or her correct position. It probably grew out of someone’s observations that may successful riders sit on their bicycles with their knees somewhere over the pedal spindle.”

Though the angle is the same on the larger frame the longer seat tube will terminate a greater horizontal distance from the centre of the bb. I’m not sure this will help you though. <Edit> as I assume your saddle is already the right height so will remain the same horizontal distance. </edit>

On an aside I dislike these radically kinked seat tubes to give big wheels in short back ends for a similar reason. I run my seat post high as a result of being tall and the impact is a terrible effective seat tube angle because of the top of the seat tube being at 60 odd degrees to compensate for the forward slope lower down.

The rear end of most bikes and SA is all but stick a tail on the donkey. It’s based around the average height person on an average sized bike. Almost all designs are based on a medium frame, because surprisingly that’s what the average rider will buy. The same rear end is welded on to all sized frames in that model with a slight tweak of the seat stays so they reach the different seat tube length.

On a 2 or 3 year old bike the SA will be based on a seat post that incorporates an amount of set back. Very recently some manufacturers adjusted the geometry to solve the issue of inline dropper posts, eg: Cotic on its latest batch of Soul 27.5.

Back to your question OP. If your using clips then small setup adjustments can feel massive because you are “fixed” in a spot. That spot might not feel natural. Flats allow you to move your feet a lot more, probably into positions that are not “correct” but feel comfy.

I used to work with a chap who walked very duck footed, 10 to 2. He had to have custom pedal spindles made and an extra cleat spacer so he could achieve a comfy pedaling position. He looked very odd but he was comfy.

KOPS is bollocks

On an aside I dislike these radically kinked seat tubes to give big wheels in short back ends for a similar reason. I run my seat post high as a result of being tall and the impact is a terrible effective seat tube angle because of the top of the seat tube being at 60 odd degrees to compensate for the forward slope lower down.

That’s just bad design. We are doing a lot of that style on Pact models and we will always ask for seat height, so we can ensure correct seat angle at the proper leg extension.

Ive been using the same shoes and cleats for a fair years now and never had an issue with them.

On my current bike I would never ever be able to use an inline post as it would just feel very uncomfortable.

Brant can you explain why KOPS is “bollocks”? As a frame builder/designer you can probably explain it better than most.

So what is the best way to set up for a comfortable ride then, currently I feel as though I cant get the power down properly and am starting to get a bit of hip pain too now.

my current set up feels weird….

Ive tried to set the saddle fore/aft position so my knee is just behind the pedal spindle, this leaves me riding most of the time just resting my finger tips on the bars, In turn I tried a shorter stem to bring the bars back but this made the bike to short??

If I move the saddle forward say half of sm on the rials I start to get pain in the muscle just above my knee/

I am also constanly shuffling around on the saddle to try and get comfy?

Any ideas?

hip pain too now

Saddle too high and you’re rolling your hips?

I was thinking that but Ive set the saddle height by putting my heel on the pedal at the bottom of the stroke and left a slight bend in my leg.

The theory behind KOPS is bollocks. The Bontrager link covers it well, however…

Changing from your regular position and encountering pain or feelings of oddness is completely to be expected though.

Many of my mountainbike designs are designed to put the rider in a more forward position, weighting the front wheel when seated to give a climbing position kind of like “on the rivet” but without having to shift forward to be “on the rivet”.

Road bikes, or bikes for riding around sat down more are different and benefit from slacker seat angles.

OK cheers for that, So am I right in thinking that most people riding one of your current geometry designs will more than likely be forward of the spindle then ?

It depends where they put their feet on the pedals.

I don’t think mountainbikes work well with feet clipped to the tippy toe ball of foot position. If you are going to clip in at all.

Where you foot sits on the pedal affects the relationship of the knee to the pedal spindle.

I use seat angle along with chainstay length and BB drop and reach and head angle and offset to manipulate rider weight distribution.

I mean, do you drop your saddle to go down a hill, or do you raise your saddle to go up.
I think for a lot of people it’s the latter now, whereas it used to be the former.

That sort of makes sense.

I may stick a set of flats on the bike and see what my feet do.

Any ideas why I’m riding on the tips of my fingers ?

I don’t wish to bring up unsavoury old threads but didn’t you have a bike with a rather “quirky” setup/ fit?

It could be that a trip to someone experienced at getting people comfortable on bikes gives answers quicker than a lot of internet back and forth as there are too many variables

Any ideas why I’m riding on the tips of my fingers ?

Bar height is too low / TT or stem too long / you don’t have enough core strength to hold yourself in that stretched position comfortably.

Danw I agree.

Bigblackshed I tried a shorter stem but it made the bike feel to short.

Danw I agree.

Bigblackshed I tried a shorter stem but it made the bike feel to short.

Any ideas why I’m riding on the tips of my fingers ?

Tight hamstrings and insufficient core strength.

Stretch more.

Great thread, because I’ve been thinking about this question for some time now.

It seems like the fashion with mountain bike seat posts has been more towards inline posts for some time now; you can’t get a Reverb, the most popular dropper post by a long shot, in layback for example.

However, as has been questioned in this thread, many frames with a “kinked” seat tube come with layback posts. I always presumed that this was to compensate for the steep seat angle on kinked frames, for example;

The layback post on most Specialized full sus bikes compensates for the bottom bracket being effectively behind the seat tube. Specialized’s own Command Post dropper only comes in layback variety so they obviously design their frames around a layback post.

Likewise on Renton’s latest steed, the kinked seat tube is offset with a layback post;

However, the next two confuse me. The Trek Fuel 27.5 has a relatively steepish seat angle with an inline post….

while the 29er has a really steep one

Likewise, the Whyte T130 has quite a steep angle too, running a Reverb

My main bike is a 26er Specialized Camber that came with a layback post. I’ve been running a layback post on for a year now primarily because I felt like I had too much weight over the back end climbing steep stuff (of which the local trails round my end are primarily composed of). I can climb comfortably up steep stuff with the layback but for the rest of my riding I feel like I want to push myself back on my seat because my legs just don’t feel right. I’ve tried putting the layback post on and pedaling wise it feels great but again, steep climbs it feels weird. The seat angle is around 75.5 degrees at pedalling height using an inline post so similar to the Trek 29er.

I can totally sympathise with Renton’s ongoing fitting dilemma. 😆

I guess if you (think you) need a slack seat angle or set back post then you are a bit screwed.
Steep seat angles are necessitated for long travel, big wheels or short stays. One or all of which those steep seat angle bikes have.

Im not sure about all the angles etc. I just know I am struggling to get comfy on the bloomin thing.

I like the devash always feel like Im trying to shuffle backwards off the seat?

Its weird, some days it feels to short, some days it feels to long?

Is the general consensus to forget all about KOPS then and just let my legs get used to the achy feel from slipping my seat forward a bit so Im not riding on my fingertips?

KOPS works fine for me. It puts most riders in a fairly neutral position in which weight is taken through the legs and core. Of course for some extremes such as TT and recumbent KOPS notionally makes no sense until you work out how much the rider is rotated around the bottom bracket.

Next time you are sat on the toilet, try getting up with knees above ankles, above tip of toes and above your would-be cleats ;-).

Renton – have a look at saddles too. Something like an ISM that changes the way you sit and move. You might find that by transferring weight onto sit bones it changes the knee and leg dynamics for the better.

Hi IainC

Ive changed the saddle already for a charge spoon which I have used on all my bike previously.

The giant offereing was far to flat and uncomfortable.

I know bike fits for mountain bikes are seen as somewhat questionable in there value but for someone who has as many fit problems as you Renton, is it worth getting a professional to have a look at you and the bike? It may cost a couple of quid but could well help with a few problems you have.

I like the devash always feel like Im trying to shuffle backwards off the seat?

Its weird, some days it feels to short, some days it feels to long?

Is the general consensus to forget all about KOPS then and just let my legs get used to the achy feel from slipping my seat forward a bit so Im not riding on my fingertips?
Did you try the ‘balance trick’ mentioned in the thread a while back about your bike discomfort? ie sit on the bike as normal (best done on a turbo trainer) and see if you can take your hands off the bars by a cm or 2 (or hold an imaginary bar that’s where you’d like it to be) and hold that position while pedaling gently. If not, move the saddle back until you can, or at least can hold that position for a moment without busting a gut, at which point your upper body weight is more balanced than it sounds now. Only then can you start to look at bar reach, but tbh I’d do that based on how the bike feels out of the saddle, for handling. KOPS has nothing to do with any of this, or MTB fit generally. This method assumes your saddle’s at roughly the right height to begin with, as that affects setback over BB a little.

How to fix the real cause of Low Back Pain from mountain biking.

http://singletrackworld.com/forum/topic/does-knee-over-pedal-spindle-matter-anymore

Renton – did you get round to buying another bike for commuting? Maybe having two bikes would let you set this one up as less of a compromise?

What do you lot think of this for ST angle then?

I guess the effective angle is pretty normal, it just looks odd. It looks like the design is to allow shorter chainstays while maintaining the same effective ST angle, but only the 26″ and 650b bikes are like this, the 29er (where you’d think shorter stays are more desirable) is pretty normal, without the weird kind in the ST.
Interestingly, a lot of their sponsored riders tend to climb standing up most of the time (Stephan Tempier in particular)…

I’m still looking mate. Popping over to bike reveloution this afternoon as I have an old bike to donate.

In my eyes a lot of this is down to the type of bikes, as Brant has already mentioned the steep seat angle mated to long travel (or big wheel/short stay), mostly these are the kind of bikes that you don’t pedal sat down, except on steeper climbs where the position makes sense and is similar to the old arse-on-tip-of-saddle-preying-mantis position needed for fine tuning weight bias to better maintain traction.

These are the kind of bikes that are generally (supposed) to be for stood up and more dynamic riding through techy trails that normally need a more active approach to riding, if you’re using them for sat down mile munching or commuting then the position is not going to be ideal, it’s not to say the bikes can’t do it or you can’t adapt your position to it, but that’s not really what they’re about.

More XC and shorter travel mile munchy bikes often have more conventional STA and end up (coincidentally) putting you back in roughly the same area KOPS would.

If you took a look at my Trail/Enduro (eugh!) bike and compared it to the bike I race XC on they are worlds apart in terms of shape and fit, in fact the Trail one is actually relatively short travel (130mm) but shaped for stood up riding, it doesn’t work very well sat down if I’m honest, unless it’s on steep climbs, where it actually out-tractions anything else I’ve ridden. The XC bike is much better for seated powerful pedalling and is a bit more of a handful when stood up. They both work very well but for different purposes, I also have something a bit more in the middle for in the middle type riding.

None of that really helps you Renton I’m afraid, just brain-splurting my thoughts, hope you can get comfy (or used to it!) though, nothing more annoying than a bike you love but can’t get happy on.

Why standing pedaling is better than seated pedaling…once you know how.

Is Standing Pedaling really better than Seated Pedaling?

just back in from a ride having moved my saddle forward about 4 mm.

Felt loads better to be honest and legs only feel a bit achy in some Places.

I think trying to commute on it isn’t helping at all to be honest as I’ve tried to set it up for thaT which isn’t helping.

I don’t get on with steep seat angles, I don’t feel in the right position to pedal. I do have a long leg to torso ratio though so suspect this may have some bearing on it.
I also find the lower your bars are, the more stretched out you need to be to achieve a comfortable position, so with long legs I have my seat raised quite high and need quite high rise bars and spacers to get a setup that feels balanced.

I think trying to commute on it isn’t helping at all to be honest as I’ve tried to set it up for thaT which isn’t helping.

I do think this is a big thing. Buy yourself a cheap road bike for the commute and set the MTB up for the trails.

^^^^ yeah, get that Merlin road bike bought 🙂

Too much mate.
I am waiting to hear back about a btwin triban 3.

I don’t get on with steep seat angles, I don’t feel in the right position to pedal. I do have a long leg to torso ratio though so suspect this may have some bearing on it.
I also find the lower your bars are, the more stretched out you need to be to achieve a comfortable position, so with long legs I have my seat raised quite high and need quite high rise bars and spacers to get a setup that feels balanced.

This is my problem too Steve. I’m more or less dead on 6ft (182/ 183cm depending on the time of day 🙂 ), long legs, shorter torso, average arms. Medium frames are way too small for me as I’d have to run a 90-110mm stem and long post which just feels wrong on a modern trail bike. The fit on large frames is effective top tube dependent and bar height plays a part too as I still need to have my seat quite high.