Set up Help

mjjbuk

Hi there, I'm a smidgen under 6ft and have had a 58cm Trek for the last few years. Just joined a club recently and am increasing my mileage and am getting some knee pain AFTER cycling not during. I wanted to check my set-up but the problem i'm having though is adjusting my position to get correct knee alignment on the 45 degree position. See the image below. My seat can not go back anymore and my seat stem can not go up much further (maybe another few mm) as my feet won't be able to touch the floor. Is there anything else I can do or is this bike just wrong for me? Thank you...

MichaelW

Your feet touching the floor is not a part of the bike-fit equation. They dont need to touch.
You may need a longer seatpost with more layback.
Also, check your crank length. This should be at least 175mm for a big rider.
Set the stem in relation to the saddle after you have a correct saddle position.
Knee Over Pedal Spindle (KOPS) is a starting point for the riding position. You should also look into your cleat positioning and pedal float.

mjjbuk

Thanks MichaelW, good avise about the feet not having to touch the floor, didn't even occur to me that they didn't need to.

BruceG

Also unless it was fitted by a useless plumber the top of the radiator in the background should be at 90 degrees to the yellow line you have added which it clearly isnt, if you adjusted the yellow line to a correct position I am sure it woudl indicate that your KOPS (knee over pedal spindle) postion is near enough correct.

The pain you are experiencing may be caused by cleat position or saddle height, which it seems you may have to low.

mjjbuk

Good point BruceG, I've rotated the pic accordingly, raised the seat post and the KOPS seems much better(?)... New pic below.

BruceG

A good rule of thumb I have used to get seat height in the ball park, is to position the crank arm such that it is in line with the seat tube, with shoes removed and sitting on the seat in your normal position you leg should be at maximum extension to get your heel on the pedal, some say this should be done with shoes on, however I was taught shoes off many moons ago and have always used that with success on helping others. As already mentioned relative to getting your feet on the floor this will feel too high, BUT remember you are setting your saddle height for riding the bike not putting your feet down. Hope this helps. If you are still experiencing knee pain after this I would explore cleat position.

mjjbuk

Thanks BruceG, just tried that crank arm test and it's pretty much there so I'll do a test ride tonight and see how it feels.

Thanks both for your help...

Pross

I can't see the photo unfortunately. However, a general riding position will have:-

1. Knee slightly bent at the bottom of the downstroke i.e. when crank is following the line of the seat tube (adjust by raising lowering seat post).
2. Knee in line with the pedal axle when pedals are at 'quarter to three' position (adjust by moving saddle forward / aft on its rails, keep saddle level)

When riding the stem length should be such that the tops of the bars obscure sight of the front wheel axle and, if you are a real beginner, it is best to start off with little drop from the saddle to the top of handle bars.

You don't mention if you are using clips or not? If you are fixed into the pedals then that may well be a cause of knee pain. The pedals will often have some side to side movement but small amounts of variation fore and aft can make a big difference.

The emphasis here is on the 'general position'. A shop with good bike fit facilities will help tailor it to your specific needs.

mjjbuk

Thanks Pross, really helpful stuff. I think I have tweaked most of what you said already and am going out shortly to see how it feels. I am using grey Keo cleats with 4.5 degree float. I will look at the cleat positioning next if still a problem.

Pross

mjjbuk wrote:

Thanks Pross, really helpful stuff. I think I have tweaked most of what you said already and am going out shortly to see how it feels. I am using grey Keo cleats with 4.5 degree float. I will look at the cleat positioning next if still a problem.

I was getting knee pain a lot last year, first time in 20 odd years. I moved the cleats back a couple of millimetres (assumed that was the problem as the pain started shortly after I put new cleats on) so that my foot was slightly further forward and it solved the problem. It should be relatively easy to check if they are in the correct lateral position and angle as you should be able to rotate your foot in either direction from where it sits in the pedal.

mjjbuk

It's a tricky business getting the positioning of everything just right. Cleats are next on my list, it's no fun having knee pain all the time. Cheers Pross.

Wheelspinner

This guy always has some useful information about bike fitting, well worth a read...

http://www.stevehoggbikefitting.com/blog/2011/04/power-to-the-pedal-cleat-position/