seat height arithmetic
 

lets do some math! seat height from BB to seat based on lemond method is 30.5 inches. bike A has toe clips, platform pedals and uses soccer shoes. bike B uses spd sl pedals which are 1/2 lower then bicycle A's platforms, AND the sole of the shimano bicycle shoes is apx 1/2". the soccer shoes are apx 1" high. confused yet? so, by my approximation, bicycle B should have the seat lowered 1 inch to match the overall seat to pedal connection of bicycle A. does this make sense?

Ugh. I just helped my kids with the maths. I'm done for the night.

Shouldn't this be in the Fitting Your Bike forum?
http://www.bikeforums.net/forumdispl...ting-Your-Bike

Yes. Exactly.

It makes math sense.

It may not make real world sense. It doesn't take into account shoe flex and clothing. If you're wearing soccer shoes they may be more flexible (? not sure if this is true). At the bottom of a firm downstroke you may flex the shoe 1-2 inches downward, at least at the heel area (which is really what you're trying to control since that's attached to the rest of your leg).

Also if you're not in cycling clothing you may not be sitting on the same amount of material. It may be more. I know that wearing bib knickers under bib shorts, both with padding, messed me up in terms of saddle height when compared to just bib shorts or just bib knickers. The US National Team had a minor crisis when the weather got warm because everyone got sore etc. It ended up that when they stopped using their (thick) tights their effective saddle height dropped a few mm. This was enough for the riders to noticed something awry.

If Bike A feels like the saddle is too high those would be the two things I'd check.

From my own experience I like to have "casual" bikes set up with a lower saddle height, meaning those that I'm riding with sneakers and in street clothing.

^^^so then does the notion of the multiply inseam x .883 method seem outdated or need some updating? it was designed to take average shoe height and pedal height into account but i bet pedals and shoe soles have become much thinner over the years. speedplay pedals with a thin soled shoe are probably way thinner then sidis and first gen. looks from the 1980s.....

When I mention "shoe flex" I'm thinking of a sneaker type shoe. I don't play soccer so I have no idea if a soccer shoe is like a clipless pedal cycling shoe or not. It probably isn't if its sole is a full inch thick.

The Lemond rule seems to be a good starting point. My understanding is that it has some assumed shoe and pedal dimensions, so you'd subtract them out and insert your actual shoe/pedal dimensions.

My saddle position, relative to the BB, has gone down a lot between the mid 90s and now. The primary reason was changing pedals and shoes and then later changing crank length. The saddle->"bottom of my foot while it's in my cycling shoe while clipped into the pedal" distance has stayed within a narrow range though.

Or better yet.............sit on the bike as if riding and with your left or right leg extend the pedal of either to its lowest position and then adjust seat height to what we all know is just slightly bent knee but not extended.

Do this with a friend so you can stand on the bike while they adjust the seat.

No math needed here.

the lemond rule as-is has worked for me well for set ups with platform pedals. i just did the straight equation and set the seat based on that number. great! using that number for proper clipless pedals hasnt worked out so well. ive also recently made the switch to spd-sl from speedplay so there is still a learning curve i need to adjust too. overall though, spd-sl's with my current road shoe are at least .75 inches lower then a toeclip and soccer shoe/skate shoe set up on my city cruiser. ill lower the clipless setup and see how that goes.