Dull question about frame size and angles.

explosifpete

Hello I hoping that someone can help me with my frame dilemma.
I currently ride a kinesis RC2 frame but wanted to upgrade to something stiffer and better for putting the power down.
I am really fussy so bare with me!
The kinesis is an ok fit but the top tube is a little long and I have to run the saddle far forward on an inline post so I want a shorter one, also I don't like having loads of headset spacers (currently have 10mm) so a long head tube is good.
I've been looking at the Dedacciai scuro rs as I like it as the measurements look good but then i'm a bit unsure as i'm 5'10 and the size i'm looking at is recommended for people over 6'
Is there something i'm missing as the medium has a 53.5 top tube and that's tiny

RC2 RS
Size C/T 51 L
Head Angle 74 72
Seat Angle 73.5 73.5
HTT Length 57.1 55.0
Wheel Base 98.7 ?
B/B Height 27.1 ?
Chainstay Length 40.5 41.0
Headtube Length 16.5 17.3


Thanks for sitting thought this extremely dull question

22-48

Your saddle position is mostly independent (ignoring center-forward) of the top tube length and tied directly to seat tube angle.

If your saddle is that far forward you either have it in the wrong position or the seat tube angle is too slack. I would look at that first.

explosifpete

but surely these to frames having the same angle of 73.5 the top tube length would be the deciding factor?

22-48

Yes, except for the fact you are running your saddle far forward on an inline post, suggesting as i mentioned before either your saddle is in the wrong position or the seat tube angle is too slack.

explosifpete

by wrong position do you mean in relation to reach or where i'm sitting over the b/b?

57.1cm is a pretty long TT

22-48

In relation to the bb, or more importantly your pedal axles when cranks are horizontal. You shouldn't be adjusting saddle position to correct reach issues.

explosifpete

I moved it forward as I found i was sitting on the nose and prefer to sit over the bb as I seem to go faster. reach is fine as I have a 120 stem on at the moment and could go longer.
So I take your point I need a steeper seat angle rather than a shorter top tube
Any ideas on a frame?

explosifpete

ARRRRG

Just been reading about bike fit and how a shallower seat angle uses quads and butt power and the steeper angles are good for triathletes as it uses more of the hamstring.
I never run, have huge quads and love sprinting so i'm back to the 73angle

22-48

I give up!

explosifpete

don't give up!

22-48

Ok

your saddle has an optimum position relative to the BB that puts your knees in the right place in relation to the pedal axle, and thus optimizes power and cadence. It's a bio mechanical position based on your leg length, and sitting posture/pelvic flexion, so if we take that to two extremes, a 50 degree seat tube angle and a 100 degree seat tube angle. the saddle position relative to the bb does not change but you would need wildly different seat posts to accommodate those two frames !

get your saddle position correct then look at reach, which can be achieved through TT and stem length

Hope that helps. :?:

explosifpete

Thanks
....................................