Seat tube angles on DJ bikes!

Lee, was checking in and read How seat tube angle affects bike character. Have you ever ridden a Cannondale Chase 1 DJ? Both small and med frames have a 77 degree seat tube angle and 69 degree head tube angle. What would be the purpose of such an extreme ST angle unless perhaps it does not matter if you don’t use the seat as a peddle platform. BTW love my Chase!!!
Enjoy those kids- they grow up too fast.

Mike

Hey Mike,

Thanks for the interesting question. I have not ridden a Chase.

For the sake of comparison, we’ll compare the Chase to another popular DJ bike, the Specialized P.3. (BTW love my Mighty P.3!!!)

The Chase has a 77-degree seat tube angle. The P.3 has a 72-degree seat tube angle. Otherwise, those bikes have very similar geometry. For a DJ/pump rider who doesn’t sit on the seat, these are the key measurements:

Bottom bracket height. Almost identical.

Chainstay length. Almost identical.

Front center (the distance from bottom bracket to front hub). Almost identical.

Handlebar location. Given the right stem/bar, they can be identical.

Standover clearance. Comparable.

Ignoring material and component variables, these bikes should jump, pump and jib like brothers.

So why does the Chase have such a steep seat tube angle? I’ve asked a smarty-pants at Cannondale. Until I hear from him, it’ll be fun to guess:

Shorter chain stays? The older Chase has a 74-degree seat tube angle, and its chain stays were an inch longer. By angling the seat tube forward three degrees, Cannondale was able to tuck the rear wheel farther forward. Seems like a slick way to shorten the rear end without drastically re-working other aspects of the frame design.

Better tricks? Maybe the farther-forward seat helps Aaron Chase-style tricks? Maybe you can grab the seat in your teeth? (Dude, that was a sick Superman Incisor!) I am a trickless fellow, so I have no idea there. But Jeff Lenosky is a very tricky fellow, and his STP has a pretty normal 74-degree seat tube angle. Dunno.

Until someone tells me different, I’m going with the shorter chain stays.

Always fun.

— Lee

Know more. Have more fun!

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