Changing frames different angles and saddle setup

JamesB Posts: 1,184
edited January 2012 in Workshop
Soon to change frame from a 73.75 seat tube to 73 seat tube but using same seatpost and saddle. With 73 cm from centre BB to centre seat clamp point my calcs indicate that I`m going to have to move saddle fwd 9 mm on new 73 deg frame to obtain same position over BB centre----this seems quite a bit for a small change in seat tube angle; can anyone confirm I`m working this out right (used sine of angle and distance hypotenesue to work this out)
thanks :)


  • Monty Dog
    Monty Dog Posts: 20,614
    Measure your existing set up i.e. saddlenose behind BB spindle distance and then just make sure your new bike is the same? Your maths sounds correct and obviously varies depending on the length from BB spindle to top of saddle
    Make mine an Italian, with Campagnolo on the side..
  • Wirral_paul
    Wirral_paul Posts: 2,476
    I make it 6mm forward myself to be honest
  • JamesB
    JamesB Posts: 1,184
    Thanks guys for this, will enjoy setting up new bike when frame arrives....March time :):):) and Spring in the air too, I hope