Thanks for the clarification and input. So the measurements I gave you are actually the Pad X and Pad Y measurements then not stack and reach correct? When I enter my height and inseam in the Canyon website they suggest a size small (S) frame. Can you explain the difference please?
I'm sorry. I know it can get confusing and that's why I'm so adamant about these "terms of art".
Stack and Reach is a place on the frame. There are times when discussion of that spot is important but, on this thread in particular, we need to talk about where the body touches the bike: the arm pads (and saddle, pedals, aero extensions). So Pad Y and Pad X is what's critical to prescribing a new tri bike and a new super bike for sure.
The numbers you gave me (598/459) those are Pad Y and Pad X respectively. However you referred to them Stack and Reach and for your current bike but they are not Stack and Reach - those numbers really are Pad Y and Pad X
and that goodness as it makes my job so much easier!
Now, the explanation between my prescription of a Medium and Canyons site saying you need a Small. Great question, glad you asked. Canyon wants to sell bikes via the internet and to do it they must have a method to tell the customer their size. So Canyon's site has a mathematical equation (algorithm?) that takes some of your body measurements and predicts what size bike will work. That method is the third best way to prescribe a bike. It works well and often. The second best way is to take someone's existing tri bike (assuming they like the fit) and measure the Pad Y and Pad X off that bike and use those numbers to prescribe a new bike purchase. And then the #1 best way is to have a well educated, well seasoned bike fitter who owns a dynamic fit bike take you through the process of finding your optimal Pad Y and Pad X and then we pick the bike based on those numbers.
So when you put your body measurements into their site it suggested a small. When we took the Pad Y and Pad X off the existing bike we got a Medium. Let's go with that as it's a better method to use.
I'd like to take a sec to defend Canyon's site in two ways:
1) The Small will work, but you'd need the long stem and that doesn't come stock - you have to purchase that seperatly.
2) 99.9% of bike shops use a method that I would argue is worse than what the site uses. Here's that method: you walk into the shop. You approach the sales person. You say, "I want to buy a new tri bike". The sales person asks your height and you tell 'em, I'm 173cm (or, if you're in the States "I'm 5'8"). And the sales person says... great, I've got a 54cm bike right over here. I would argue that that method is a step yet below the Canyon site numbers crunch.
Of course if you walk into a "fit first" shop or into a bike fit studio then you've landed back at the #1 way to have your bike purchased.
Ian Murray http://www.TriathlonTrainingSeries.com
I like the pursuit of mastery
Twitter - @TriCoachIan