wotsit..

[jimboalee]

I think Randochap is suspicious your 'Inseam' measurement is wrong.

L ( leg length ) = H - S.

 

[velocidad]

this is driving me potty i've tried every method now and they all come out with completely different results.
jimboalee have i got you right? are you using your leg length (standing height - sitting height) and using that x 0.883 ?
if so that gives me 170-87=83cm 83x0.883=73.3cm measured from the centre of the BB to the top of the saddle surface. this gives me a crazy high saddle, i'd need platform shoes to ride it

 

[youngoldbloke]

To return to the OP - worth reading the following which answers most of the questions re. bike fit:

http://www.chiropracticperformancecentre.ca/Handouts/Lifestyle/Road Bicycle Fit.pdf

- recommend you take a look at this link.

 

[Randochap]

this is driving me potty i've tried every method now and they all come out with completely different results.
jimboalee have i got you right? are you using your leg length (standing height - sitting height) and using that x 0.883 ?
if so that gives me 170-87=83cm 83x0.883=73.3cm measured from the centre of the BB to the top of the saddle surface. this gives me a crazy high saddle, i'd need platform shoes to ride it

There's nothing very complicated about this. Let me reprise the measurement part of my earlier post in this thread:

Stand with bare feet 6 inches apart, facing a wall. Take a good sized hardcover book and use it as a "square," pushing it firmly into your perinium and squaring the front of the book on the wall. Measure from the floor to the top of the book spine. Do this several times and split the dif. That's your standover. Multiply by 0.883.

That's all.

 

[jimboalee]

this is driving me potty i've tried every method now and they all come out with completely different results.
jimboalee have i got you right? are you using your leg length (standing height - sitting height) and using that x 0.883 ?
if so that gives me 170-87=83cm 83x0.883=73.3cm measured from the centre of the BB to the top of the saddle surface. this gives me a crazy high saddle, i'd need platform shoes to ride it

The way you did the measurements gives you an inside leg ( or 'Standover height' as RandoChap quite rightly expresses ) of 49% of your height.
That is normal.

If you use the book method - and there is nothing wrong with it, except the book might move accidentally - the result could be up to 5mm ish LONGER, depending how hard you shove the book.

The seated method uses the weight of your torso to flatten the buttocks and sit the perinium on the floor.

The 'platform shoes' you mention might be your cleats and the thickness of the shoes, which should have a stiffening bar inside the sole.

 

[velocidad]

i've previously measured with the book against the wall and all that, which gives me a stand over of 78.5cm in bare feet. 78.5 x 0.883 = 69.3 which is 4cm lower than the standing height minus sitting height measurement.
so while i realise each method is easy enough, they just don't tally up. one is too high and one is too low. i know i could just split the difference, but then i may as well abandon the numbers and just guess
and i'm still think it would make more sense to measure stand over etc in the shoes you cycle in.
and then there's the hamley (think that's the name) method of 109% of inseam, and measuring from pedal axle to top of saddle, and this gives different saddle height again
cheers, velocidad

 

[velocidad]

actually checking again, the hamley and lemond methods are quite close using the inseam measure of 78.5cm.

 

[youngoldbloke]

What does it actually feel like if you use the Lemond/Hamley results to set up the bike? Remember this is just a starting point. For me the figures are remarkably close - to within a few mm. Your crank length could make a difference too.

 

[jimboalee]

If you're inside leg is 78.5, that's 46% of your height. That sounds medically abnormal.

Are you using LOOK type pedals?

Try the sitting method again and multiply by 0.875. ( 7/8 ).

 

[youngoldbloke]

Where is the evidence for that (somewhat rude) statement?

 

[velocidad]

If you're inside leg is 78.5, that's 46% of your height. That sounds medically abnormal.

Are you using LOOK type pedals?

Try the sitting method again and multiply by 0.875. ( 7/8 ).

medically abnormal i may well be but i reckon my inside leg measurement is spot on. i don't use LOOK pedals just flats.
standing minus sitting x 0.875 still leads to a saddle so high that rocking my pelvis is the only way i can pedal.

cheers, velocidad.

 

[jimboalee]

Dunno. Worked for everyone I've set up a bike for.

Sitting height is straight forward. Can't make a mistake, unless you clench your buttocks.

 

[velocidad]

Dunno. Worked for everyone I've set up a bike for.

Sitting height is straight forward. Can't make a mistake, unless you clench your buttocks.

certainly not saying it can't work, only what happens when i use this method. i will check all my measurements again though.

cheers, velocidad.