Bike fit fore & aft. Is that the same on different size bike

Whiteeddymurphy
Whiteeddymurphy Posts: 169
edited July 2014 in Road beginners
Daft question I know but my last bike fit before I packed in was on a 54cm. I have recently returned yo cycling and only could find a cheap Trek in a 56cm available at the time. I have all measurements but which ones do I use if any. Ie the fore/aft was 75mm. Would this be the same? Should the seat to bar length be the same ? Ie reduce stem if required. On 1st ride out it felt ok but seemed to get aches from calves & noticed my left knee had a bit pain when I got back after only 10 miles (@15.1mph.av)

I can't afford another bike fit so was wonder which if any measurements would be the same or should I make new ones. I haven't a turbo trainer to set it up etc. do it's going to be a bit of a chew

Please advise!

Comments

  • JayKosta
    JayKosta Posts: 635
    1st) saddle height - if new crank arms are different length than before, then the height (from center of BB) might also be different.
    2nd) saddle forward-backward - so knee-over-pedal position is similar.
    3rd) height of bars - for similar reach to bars, hoods.
    4th) position and angle of hoods on the bars.

    Jay Kosta
    Endwell NY USA
  • styxd
    styxd Posts: 3,234
    Saddle height and reach to the bars should be kept the same/pretty similar. The rest you'll need to adjust till you feel comfortable.
  • John.T
    John.T Posts: 3,698
    If your other bike fitted OK then use all the same measurements starting with the saddle to pedal height and set back. These should be quite easy as unless the new bike has a different seat angle you just need less seat post out. Stem length to give the same distance from saddle to hoods.
    My Fleet.
  • Whiteeddymurphy
    Whiteeddymurphy Posts: 169
    Thanks for the replies. I just wish the seat height was from the floor as would be easier to measure.
  • Anonymous
    Anonymous Posts: 79,667
    What if the tyres were flat, larger, bigger, smaller? You pedal against the pedals, not the floor! Also some bikes are higher/lower from the floor anyway!
  • MichaelW
    MichaelW Posts: 2,164
    Your reference point is the bottom bracket not the floor.
    take account of crank length at 3:00 and 6:00
    Angles vary from frame to frame so I prefer to use [x,y] coordinates for transferring points of contact.

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