Strange question or not!

fishingguy

Been looking at bike fitting. Too late as I have bike 56cm I'm 5'9-10". Anyway when I read about using a plumb bob to check the position of knee to cleat the line is 20-30 mm past my cleat. I can't get my seat any farther forward as its at the back of the rails. Questions are. Can I turn seat post around allowing me the adjustment I need or do I not need to bother. Slight pain in knees at times otherwise fine. Cheers for any comments

pinarellokid

never heard of this,, what should the measurement be ??

can you explain how you measure this please ,, very interested..

also i reckon if you can turn the seatpost round and get the saddle to fit im sure it will be fine..

iv heard of this before for TT bikes. turning the seat post around i mean.

fishingguy

I looked at loads of sites about bike fit set up and they all mentioned that with your cranks level at say 9-3 o clock or horizontal that if you drop a plumb line from your knee the line should be in the middle of your cleat, pedal or ball of foot.

declan1

I have the exact problem. I've ordered a Thompson set-back seatpost from Ribble, which you can reverse. It should hopefully sort me out! You probably can't turn around your existing seatpost as most just end up with the saddle pointing at the sky.

night_porter

I have to be honest and say that I do not have experience with the Thomson seatpost you are talking about but from my understanding it will give you "more" setback than an ordinary seatpost not less.

If you try and reverse a seatpost you will find that the seat angle is wrong for you to sit on it, I think what you need is an "in-line" seatpost that has no setback or layback and that will bring your saddle forward i.e. closer to the bars.

jouxplan

fishingguy wrote:

Been looking at bike fitting. Too late as I have bike 56cm I'm 5'9-10". Anyway when I read about using a plumb bob to check the position of knee to cleat the line is 20-30 mm past my cleat. I can't get my seat any farther forward as its at the back of the rails. Questions are. Can I turn seat post around allowing me the adjustment I need or do I not need to bother. Slight pain in knees at times otherwise fine. Cheers for any comments

The method you are referring to can be called 'knee over pedal spindle' or 'KOPS'. It is something that seems to have been around forever, and yes, it is suggested in many articles on bike fitting. Until a few months ago, I thought it was gospel.

Have a look at this article, which is what changed my mind - http://www.stevehoggbikefitting.com/blog/2011/04/power-to-the-pedal-cleat-position/

In a nutshell, there is not really a relationship between knee and cleat. They are separate issues. For the cleat, you are better off with a cleat that is located BEHIND the pedal spindle, in a manner described in the above link.

In terms of your knees, the thing to do is get the saddle height right (see here http://www.stevehoggbikefitting.com/blog/2011/02/seat-height-how-hard-can-it-be/ )

and then get saddle for aft right - see here http://www.stevehoggbikefitting.com/blog/2011/05/seat-set-back-for-road-bikes/

This last link talks about the problems with using the plumb bob technique. Try these ideas first, before you decide your bike is the wrong size. You can always try an in-line seat post, if you currently have a standard 20mm off set one. Turning posts round can be done sometimes, but it can look ugly!

Hope this helps

declan1

night_porter wrote:

I have to be honest and say that I do not have experience with the Thomson seatpost you are talking about but from my understanding it will give you "more" setback than an ordinary seatpost not less.

If you try and reverse a seatpost you will find that the seat angle is wrong for you to sit on it, I think what you need is an "in-line" seatpost that has no setback or layback and that will bring your saddle forward i.e. closer to the bars.

The setback is designed to put the saddle further back, yes. However it is possible to reverse it so it moves the saddle further forward (Thompson even confirm this on their website). I was going to get a Profile Designs Fast-forward, but they didn't do one long enough for my needs.

Grill

fishingguy wrote:

Been looking at bike fitting. Too late as I have bike 56cm I'm 5'9-10". Anyway when I read about using a plumb bob to check the position of knee to cleat the line is 20-30 mm past my cleat. I can't get my seat any farther forward as its at the back of the rails. Questions are. Can I turn seat post around allowing me the adjustment I need or do I not need to bother. Slight pain in knees at times otherwise fine. Cheers for any comments

You can get an inline seatpost or a shorter the stem. Pretty much the only options to lessen reach.

I'm 5'11" and had a 56cm (toptube) until a couple weeks ago. I had the same issue of being too stretched even with an inline post and the seat jammed forward and a 100mm stem (really didn't like it as it made the handling quite twitchy). I went for a proper fit and sure enough the bike was too big. Ended up buying a 54 (w/a 55cm toptube) and the difference is night and day. In the two and a half weeks I've had it it's already seen 800+ miles a 12 hour TT yesterday. I never could have done this with the old bike and couldn't be happier.

So your options are to compromise the fit on the wrong frame, or look at getting the correct sizing. For now you may just feel pain in your knees but as your mileage and distance improve you're going to run into many more problems.