Geometry/fit question

[little.man]

I have been trying to determine if a bike, IF XS, on ebay will fit me. Geometry in the attached. Last 2 bikes have been 51 CM Quantum Pro Klein and a Cervelo R3 with a 120 stem. The Cervelo looks close, but the standover heights are definitely different.

Thanks for any input.

[JimmyTango]

Well, here's how I see it:

Because there is no stack and reach given for the IFxs, I turn to:

A) comparing the toptube length and seattube angle between the two bikes to get an idea for how "long" they are.
In this case the TTs are only 1mm different in length, but the IFxs has a steeper seat tube so is a longer bike by something like .5-1 cm. No problem there as you can just switch from the 120mm stem on the Cervelo to a 110 stem on the IFxs to get close enough to the same reach to the bars (given that you set up both bikes with the same saddle height and setback, of course).

and B) comparing the BB drop to the HT length to get an ideal of how "low" they are.
It's hard to make out, but I think the IFxs is noted as having a 73mm bb drop, which is 5mm lower than the Cervelo's BB. They both have the same HT lengths, so the IFxs will be effectively 5mm less "low" than the Cervelo. If you have any spacers on your current Cervelo setup, just reduce the stack by 5mm when you build the IFxs to get the same drop from saddle to bars (or, if you are already slammed you could run a stem with a steeper drop angle).

So, without complicating things with weight distribution differences, if you want to achieve the same fit in terms of contact points all you have to do *theoretically* is 1) set up the IFxs with the same saddle height and setback from the BB that you are currently riding on your Cervelo (which will mean getting a seatpost with more setback or just moving your saddle back on the rails <1cm), and 2) run the IFxs with a 110mm stem with 5mm less spacers than you have the Cervelo set up with.

[pdmtong]

So, without complicating things with weight distribution differences, if you want to achieve the same fit in terms of contact points all you have to do *theoretically* is 1) set up the IFxs with the same saddle height and setback from the BB that you are currently riding on your Cervelo (which will mean getting a seatpost with more setback or just moving your saddle back on the rails <1cm), and 2) run the IFxs with a 110mm stem with 5mm less spacers than you have the Cervelo set up with.

FWIW I agree with the above. Are you running a setback post on the cervelo? how much setback? where is the clamp on the rails (rear, centered, forward)?

if you are running a straight post on the cervelo you would go to a 15mm setback on the XS and saddle would move 5mm forward on the rails.

if you are running a 15mm setback post on the cervelo you would go to a 25mm setback on the XS and saddle could stay in approx same spot.

if you are running a 25mm setback post on the cervelo the XS is going to move your saddle rearward about 1cm using the same 25mm setback post meaning now the clamp is 1cm closer to the nose. you may or may not like that "look"

[ultraman6970]

Thats a really long bike for the size.

[Dave]

Not much different than a colnago of the same size.

[cmg]

the reach on the cervelo will be shorter. you may not need the 120 stem

[little.man]

Thanks for all of the helpful replies. Very much appreciated.

Mark

[djdj]

Don't forget to take into account whether the two frames use different headset styles, which may affect the height of your stem and the reach.