Buff Posted January 8, 2007 Share Okay, so I've upgraded to Campy... finally... but now I'm riding 175 cranks as apposed to 172.5's.Here's the question: Do I drop my saddle by exactly 2.5mm? Ta Link to comment Share on other sites More sharing options...
Gumpole Posted January 8, 2007 Share No, otherwise the distance from top of pedal to saddle will reduce by 5mm! Link to comment Share on other sites More sharing options...
linnega Posted January 8, 2007 Share ...so you may want to raise your saddle 2.5mm. Frankly, I wouldn't bother - 2.5mm is no big deal in terms of saddle height. Link to comment Share on other sites More sharing options...
Buff Posted January 8, 2007 Share 2.5mm makes a difference when you're been sitting in that position for 7yrs Maybe I'll just change it a mill at a time and see how it goes. Link to comment Share on other sites More sharing options...
Barend de Arend Posted January 8, 2007 Share 2.5mm makes a difference when you're been sitting in that position for 7yrs I changed from 170.0mm to 172.5mm after four years. It felt exactly the same, so I checked the writing on the crank. Yep, it was longer. I feel a much bigger difference when getting off my powercranks and on the normal cranks: it feels like the normal cranks are 20 mm shorter, even though they are the same size. Link to comment Share on other sites More sharing options...
SwissVan Posted January 8, 2007 Share If you are worried about the change of 2.5mm then drop the saddle height by half 2.5mm (hmmm = 1.25mm) which is a fraction more than a BH. Or you could leave it as it is and see how you feel after a few rides and if any new niggles creaks and groans appear adjust the saddle height accordingly. (Might have to move it up or down, depends on how hi / low it was set pre new cranks). Link to comment Share on other sites More sharing options...
Sir Fed Posted January 8, 2007 Share since your cranks go round in circles, you may want to consider moving it back, or forward, by 2,5mm ... Crank length is not a factor when determining saddle height, leave it where it is and avoid the tendency to crunch monster gears with your new found power. At least until your body is used to the changes. Link to comment Share on other sites More sharing options...
Hype Posted January 8, 2007 Share No' date=' otherwise the distance from top of pedal to saddle will reduce by 5mm![/quote'] Please forgive my ignorance but if the cranks are 2.5mm longer then how does lowering saddle height by 2.5mm result in an increase in distance from pedal to saddle of 5mm ? Link to comment Share on other sites More sharing options...
Barend de Arend Posted January 8, 2007 Share No' date=' otherwise the distance from top of pedal to saddle will reduce by 5mm![/quote']Please forgive my ignorance but if the cranks are 2.5mm longer then howdoes lowering saddle height by 2.5mm result in an increase in distancefrom pedal to saddle of 5mm ? reduce == decrease. At the top of the pedal stroke, your knee will be 5mm closer to your chest, and that could be a problem in the drops. Link to comment Share on other sites More sharing options...
Hype Posted January 8, 2007 Share No' date=' otherwise the distance from top of pedal to saddle will reduce by 5mm![/quote']Please forgive my ignorance but if the cranks are 2.5mm longer then how does lowering saddle height by 2.5mm result in an increase in distance from pedal to saddle of 5mm ?reduce == decrease.At the top of the pedal stroke, your knee will be 5mm closer to your chest, and that could be a problem in the drops. Still not getting it. You lower the saddle by 2.5mm and you get a reduction of 5mm between saddle and pedals. How does that come about when the cranks are only 2.5mm longer ? Link to comment Share on other sites More sharing options...
Buff Posted January 8, 2007 Share If I leave it as is, the crank is 2.5mm longer at the bottom of the stroke but 2.5mm shorter (closer to my bum) at top of the stroke. Therefore, if I lower the saddle 2.5mm, the bottom of the stroke is sorted but the top of the stroke is 5mm closer to my ass... which is actually not a problem as you always set your saddle height according to inseam measurement i.e. you shouldn't have a straight or excessively bent knee at bottom. Link to comment Share on other sites More sharing options...
Barend de Arend Posted January 8, 2007 Share The saddle is 2.5 mm lower. (permanently) The pedal is 2.5 mm higher. (at the top of the stroke) 2.5 + 2.5 = 5.0. Link to comment Share on other sites More sharing options...
Hype Posted January 8, 2007 Share The saddle is 2.5 mm lower. (permanently)The pedal is 2.5 mm higher. (at the top of the stroke)2.5 + 2.5 = 5.0. Thanks guys. Had a bit of brain fade there. Link to comment Share on other sites More sharing options...
Barend de Arend Posted January 8, 2007 Share which is actually not a problem as you always set your saddle heightaccording to inseam measurement i.e. you shouldn't have a straight orexcessively bent knee at bottom. Unfortunately it is a problem. Crank size is almost never used in bike measurements. And it should be. You can normally get road bikes from 48cm to 63cm (ignoring compact measurements) from manufacturers. Or a 31 % change. Cranks are normally 170 mm to 180 mm, or a 6 % change. Doh! So using something like .883 times your inseam to measure your saddle height completely ignores crank lengths: if you are very short or very tall, those calculations are just plain wrong. It doesn't help, though: the bottom bracket clearance doesn't change, so if you plug a 200 mm crank on, the pedals would hit the floor. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now