So on my bike a few years back, no longer have it now was a 73 degree seattube, maybe a 57cm top tube? I had the saddle at 8.5cm cm behind the BB, now my new frame, is a 72.5 seattube, 60cm top tube when I place my saddle on the new bike, at 8.5cm why does it sit further back on the rails? the 73degree tube looked further forward? I was expecting the slacker the frame, the further the saddle would be forward at the same numbers?
seat tube angle and setback numbers
- Thread starter Samyo
- Start date
Page may contain affiliate links. Please see terms for details.
Does this help?
https://bikeinsights.com/cyclopedia/seat-tube-angle
A 73 degree is more upright than a 72.5, so the latter places the saddle forther back.
https://bikeinsights.com/cyclopedia/seat-tube-angle
A 73 degree is more upright than a 72.5, so the latter places the saddle forther back.
Oh boy, looks like im going to have to try a 110 stem out... always had 130.. 140... I think this might affect climbing out of the saddle
Ian H
Ancient randonneur
If the relationships between saddle, pedals and bars are the same, then it shouldn't make any difference.
I duno going from a 130 stem to 120 on this bike, i feel my knees brush the bars sometimes... climbing out of the saddle
Height of the bars I dont know.. not sure what the headtube measurement was on the old bike, it was a forme victeur
https://www.bikeradar.com/reviews/bikes/road-bikes/forme-victeur-review/
I now have a planet X RT-80 XLL
https://geometrygeeks.bike/bike/planet-x-rt-80-2017/
I know all the measurements except one..
80cm saddle height,
8.5cm setback
58.4cm tip of saddle to center of bars
Has same cranks and width bars 170, and 42cm
Smp saddle composite on both bikes tilt of 2.5degrees downwards
I need a 2 cm shorter stem almost to get that same length.
T4tomo
Legendary Member
well you've gone from a bike with a 57cm top tube to one with a 59cm top tube so
...shouldn't come a surprise.
I think the headtube may of been taller on the 57 frame. Idk.. how likely is it? I cant find a geometry chart for forme victeurs
T4tomo
Legendary Member
very very likely, different models have different geometries. "endurance" road with have more relaxed angles and taller head tubes than a racier or aero road bike. Brands differ in their frame tube proportions etc.
obviously its easy when you have two bikes and can set up the old one from the new one.
But in absence of that, start with getting the saddle in the right place for your pedalling action / knee position relative to peddles / KOPS etc. once that is fine then worry about bars / stem i.e. "Reach" measurements or saddle tip to centre bars. also dont forget you can nick a couple of cms or reach either way by rotating the bars a bit and moving the brake hoods to compensate. i.e centre bars remains unchanged but the reach to the hoods has de/increased.
quite a lot of "bike fit" theory articles / youtube clips.
or go and get a a bike fit, but be prepared to be told this frame is the wrong size for you!
The 57 frame, was 73degree STA and my 60cm frame is 72.5 STA my 60cm frame, headtube does look bulkier im 6ft 3, so its likely the 57cm frame was the wrong size..
T4tomo
Legendary Member
I would agree subject to the caveat that some brands label things very differently, but a 57cm top tub sounds quite short for a 6'3"
Yes thats why I had the 130, 140 stem on there most times..
