Help with Stack/Reach data
I met with my local retül fitter for a pre-fit measurement process before considering buying a new rig (Ventum, I am staring at you). 2 hours and $100, here is what he said:
stack ~555
reach ~415
Here was the final picture
.
He is a specialized retailer. Apparently my 'perfect' specialized shiv would be a stack of 565 (large), reach of 405 (medium) - which does not exist. He says my hamstrings are tight, my hip angle is should be 105 at most, that my current Trek SC is fit too aggressively (-17degrees?) and a hip angle of 103, causing me to "over reach my shoulders to maintain my torso angle" which is reducing power and causing some neck discomfort. We agreed it would be good to have some stack adjustability for short vs long races. He said he could fit me on a shiv M or L, but given all of this data, his opinion would be a medium shiv (540/405) with a "positive stem angle" and build up the shiv arm pads to achieve the larger stack needs for long course work. He felt the medium would give us more room to play with and give me better handling, whereas the large would be more ideal in terms of stack but no flexibility on reach.
Looking at the Ventum specs, very difficult for me to understand where to put myself, but I would guess 56 (ventum recommended a 54 based on data I sent from my current Trek, not the retül numbers:
|
|
54 |
56 |
58 |
|
Stack |
528 |
545 |
564 |
|
Reach |
409 |
422 |
437 |
Any thoughts?
DS
Comments
Trek - started this more correct way of measuring and fitting bikes and it just makes sense... as many have found if you buy the frame stack and reach that does not necessarily mean the arm pads and base bars will be where you want them to be... Just too many variables on the front end of the bike... Note: the comments on the Ventum thread about the bike NOT fitting with Ventum bars and the need for TriRig or 3rd party bars with more adjustment....Read this thread which explains a bit more in detail.... Trek provides a database for their bikes where you plug these numbers in and you can get a prescription on which size frame, which stem, and how much additional range you will have...
http://www.slowtwitch.com/images/trek/SC_FitGuide_final.pdf
What Tim said!
Also..I went with the TriRig Alpha X bars to get my Ventum dialed in. Once you have the arm pad stack and reach numbers you can plug the numbers (and the frame stack/reach) into the TriRig Alpha fit webpage and they tell you exactly how to configure the bars (undermount/overmount, which arm pad mounts to use, spacers, etc). Very intuitive.
The folks at Ventum should be able to tell you what arm pad stack/reach configurations are available with their bars. The stack is VERY adjustable....the reach is not. So based on that my initial reaction would be the 56 is the right size for you but you need to confirm those items ^^
The zipp website has a tool that I found useful to help me get from frame stack/reach to arm pad stack/reach. Here is the link - http://www.zipp.com/support/vukafit/index.php
Manufactures and their websites often talk about stack/reach without specifying frame or arm pad. It can be VERY confusing.
+2 - I've been pinging Todd Kenyon on this from TT Bike Fit as he did my fitting in June. He's also a Ventum dealer and getting one (Yes, he can work the EN magic dealeo if you go through him)
He's got me speced for a Zipp bar as well.
exploration is now done, I just need to convince myself this is actually worth anything over my P5, or that the tri-geekery is worth the dough