Thanks for the response. I did as you suggested with the wall and got a distance of 436 to the middle of the pad. I also remembered I had a bike fitting app on my phone, so I set the bike up and got this picture which seems to confirm that measurement at 436.2mm (the app does the measuring based on the wheel spindle to spindle measurement (which was 1020mm in this case).
This bike has always felt like I was scrunched up front to back, so if the pad x is too short that would help explain why.
I will also try to send you a few shots of me riding the bike in a PM, so they might also help you get a better sense of what might be going on with my position on the bike, and give you an better idea about what size would work the best.
Yeah, now we're talkin'! You've got this Pad X of 436 (middle of pad) and the bike feels "cramped/scrunched" and it is - the pics help too by the way. You elbow is currently hanging off the back of the pad quite a bit and I think you'd be more comfortable with the elbow somewhere between the middle of the pad and the back edge of the pad - that adds another 20-30mm so if we add 25mm let's make the Pad X 461. Just as your fitter suggested the bike is a bit small for you. Also, to go a step further, while the seat tube angle on this bike is 78deg you've got your Cobb Max set up a hair back of mid rail and you're sitting on the middle/back of the saddle. So....you're best triathlon position is forward of where you are now. And when you have your hips farther forward then your Pad X to mid pad would be more like 480ish. You true Pad X is somewhere around 480.
Now, let's discuss the Pad Y for a sec. When you're fitter suggest the bike was a bit small for you but that it could work - one of the ways he made it work was with the ~40mm of spacer under a stem that's in a +6 deg position. When you move forward - and here are the two things needed to move forward 1) either with the same saddle but slid forward on the rails or a new saddle where you can ride the nose in comfort and 2) cranks that are 165mm or shorter - not only will you get the Pad X you deserve but you'll get a Pad Y that's lower.
So... Pad Y is existing 675 and likely best of 650 and Pad X is 480ish and now we have an accurate prescription for a bike that'll work for you. If it's a Canyon Speedmax CF rim brake (and man, it should be!!!) then it's a Medium, the 80mm stem that comes stock on the bike will give you a range of Pad X between 467-492 so you've got lots of room fore and aft to find that perfect cockpit distance. And the Pad Y range is 585-672 which works nicely with where you belong.
Now, I have some caveats that I would be remiss if I didn't put 'em in right now... #1 this bike will likely arrive with 175mm cranks on it and that will muck up your fit. My advice is to pull 'em immediately out of the box, install a set of 165s and sell the 175s as "new-never ridden". You'll have some time to decide on rings: 50x34 or 52x36 on your new shorter cranks, you can save money by buying 105 level (it's only weight and on a tri bike that's not so important), and you spend money on a power meter if you wish. Also, If you buy a mechanical bike (as opposed to an electronic shift bike) the aero extension will be 100 miles long and to cut 'em you either need to pull the front and rear derailleur cables, saw, and then rethread cables...or...I've done some trickery in my fit studio with a Dremel tool and a cutting wheel where you can cut the end the extension that's sticking out toward your knees - cut it longways first then cut it around the tube and then pry it wide enough to slip it off the cable housing that lives inside the tube. It's not hard, it only has to be done once but something to anticipate. If you get a Ui2 bike (so great!!) the extension will still be too long but all you gotta do is unplug the ewire, remove the extension, use a logical process of cutting it (hacksaw) and reinstall with a quick plug-in and you're on your way.
Get back to me here with more questions if you have 'em.
Ian Murray http://www.TriathlonTrainingSeries.com
I like the pursuit of mastery
Twitter - @TriCoachIan