General Cycling Discussion - Current bike fit and Wrench Science

So I cruised on over to wrench science and tapped in my details.....

Height 183cm
Sternum Notch 153cm
Inseam 33inches (am going to remeasure...had 34 before:S)
Arm Length 69cm
Shoulder width 44cm
Flexibility 5
weight 69.5kilo
shoes 46Euro

According to the results my overall reach should be 73.09cm. This is Top Tube plus stem length. Currently I have 580mm TT plus 110 stem = 69cm reach. But the stem is reversed, making it slightly less. Why am I feeling the need for me to get a shorter stem if they reckon I need much longer stems? This is odd.... I always thought it was because I had a short torso? I am really confused now!

Brendon

I would re-measure everything just to be sure before making any adjustments.

Wrench Science formula had me 3 cm too high in the saddle after years of riding. I couldn't believe that I, and the fitters I worked with, were so far off. But I figured what the hey and started lowering it 1 cm at a time. It made a huge difference in my overall power, comfort and balance. I never thought anything was wrong - but "nothing wrong" didn't equate to "optimal." good luck.

55/Rad

I remeasured my Inseam and got 35inches.... I spent some time on it this time instead of doing it in a rush.

Your Overall Reach is :: 70.55cm Center-to-Center (as said earlier - using 69.0)

Your Frame Size is :: 62cm OR 63cm Center-to-Top / 59cm Center-to-Center (riding 58cm CtoC)

Your Recommended Saddle Height is :: 78.5cm (current position is within .1cm of this figure) am experienceing no problems getting power to the ground and no knee pains etc

Interesting.... it wants me to use a stem that's 1.55cm longer! and my saddle is as far forward as it will go. intersting indeed! most confusing for a young rider....

Sounds like you are real close. The program doesn't take into consideration seatpost and saddle position. I think it assumes a neutral saddle position along with a standard seatpost.

What is the C-C measurement from the reference point on the seatpost? (as opposed to the center of the seat tube)

55/Rad

Sorry? what is the reference point? I have the Cervelo Aero seat post and frame. I have a HUGE amount sticking out, as it is a compact frame. Would the angle of the seatpost and the height of it give me a longer reach?

Brendon

The reference point is the center of the guage on your seatpost (saddle) clamp. The one that you use along with the guage on the rails of your saddle to adjust your fore/aft position.

I checked out your bike (very nice!) and quite honestly, I'm not sure how to judge the sloping top tube and compact geometry for this application. But it appears you have a standard seatpost, (as opposed to a setback) so the idea of moving your saddle back in order to increase overall reach (rather than changing stems) is plausible. It would however, disturb your KOPS setting if your into that.

That said, I'd be interested to know what is the correct way to measure a compact frame for effective top tube length and until this is clarified, I'd suggest waiting before making any adjustments. Does the Wrenchscience website adress compacts?

55/Rad

I have the seat as far forwards as it will go... I think that will upset KOPS as much as anything! Cervelo has a way of calling my bike a 58cm and it is equivalent in fit to a standard 58cm? I am thinking that the set back from my seat being stuck out in the air might indeed be making that REACH figure higher than I think it is.... I shall go and measure up later but meh I'm too tired right now.

did 52km earlier and it killed me.... indeed I want to sit further back on the seat! Seat has also adjusted it's tilt by itself. blah.... have been trying to find adjustable stems to play with but no luck so far.

Ok. the Cervelo site itself helped out some - http://www.cervelo.com/bikes/SLTeam.html#Geometry - you can see how they measure the top tube and how it comes out to 58 cm.

I would put your seat back to it's center position and reverse the stem. Then re-measure the top tube and reach - it should get you close to the 70.55. From there, I'd ride it for awhile to get the feel. Then, down the road, look into changing the stem if you feel like it.

Beautiful bike - I love the philosophy of the company.

55/Rad

I already have the stem reversed... I will fiddle around and see what happens. I may have the saddle in a position that makes me feel sretched where as a more stretched position might actually feel better?

Brendon