That would be a relatively good measurement, but you also have wildly different offsets to think about then.
Plus this is mainly an issue for taller riders, who get sat much farther to the back. It could be an issue for smaller riders as well, who effectively get an even steeper seat tube angle, but given the rotation of the main frame due to differing sag values the issue is less pronounced.
Speaking of sag and climbing, seating further back over the rear axle makes changes in sag while climbing again even more pronounced for taller riders, where the actual angle gets even more slack \(because you set the sag with the bike being level\).
I'd say for anything that has to be pedalled up the hill \(this of course includes enduro class of bikes\), the primary geometry considerations should be cockpit geometry while being sat down. We spend much less time descending to optimize purely for that compared to pedalling up the hill.
Then i wouldn't be surprised if having more or less the same weight distributions of front vs. rear would bring the effective ride quality comparing different sizes of frames more in-line with each other. Maybe that would mean a steeper seat tube angle for the XL frame, which would be then sagged lower while climbing, even longer top tubes, maybe even longer chainstays \(but not the Norco way, where the move the BB forwards on larger bikes to lengthen them, thereby again decreasing the seat tube angle\).
It might even mean different suspension geometries between sizes!
May 25, 2018, 3:54 p.m. - Primož Resman
That would be a relatively good measurement, but you also have wildly different offsets to think about then. Plus this is mainly an issue for taller riders, who get sat much farther to the back. It could be an issue for smaller riders as well, who effectively get an even steeper seat tube angle, but given the rotation of the main frame due to differing sag values the issue is less pronounced. Speaking of sag and climbing, seating further back over the rear axle makes changes in sag while climbing again even more pronounced for taller riders, where the actual angle gets even more slack \(because you set the sag with the bike being level\). I'd say for anything that has to be pedalled up the hill \(this of course includes enduro class of bikes\), the primary geometry considerations should be cockpit geometry while being sat down. We spend much less time descending to optimize purely for that compared to pedalling up the hill. Then i wouldn't be surprised if having more or less the same weight distributions of front vs. rear would bring the effective ride quality comparing different sizes of frames more in-line with each other. Maybe that would mean a steeper seat tube angle for the XL frame, which would be then sagged lower while climbing, even longer top tubes, maybe even longer chainstays \(but not the Norco way, where the move the BB forwards on larger bikes to lengthen them, thereby again decreasing the seat tube angle\). It might even mean different suspension geometries between sizes!