Do you have a picture of you on both bikes or the fit coordinates he uses for both bikes. The p5 is very adjustable initially. There should be no reason why you can't get the same position.

The old p3/p4 can be an issue to switch to the p5 since they had very low stacks compared to the p5.

I had similar pain as you, and wound up needing to move my pads wider. When I did this, all the crazy pressure and neck/back pain went away.

definitely encouraging to hear. maybe I just need a better fit and time to adjust. Thanks for the help

I dont feel too stretched out for sure. If anything, maybe a little too crunched up. almost like my knees have to widen out to pedal as opposed to staying close to the frame the way they do on my P2. as for the saddle, i will bring both when i do the new fitting and see which is best. Thanks

Not sure the stem length on my P2. Its the blue and white frame set that was made in 2014 and 2015. I purchased it used. The guy i bough the bike from tried me on the 54 and said it stretched me out too far and thats why he recommend I buy the 51. then he dropped down the stem height as low as he possibly could to get my elbows to the angle he thought I needed to be.

Why don't you just measure the pad stack, and the pad height, of both bikes. Post the results, then folks here can maybe help with ways to get the numbers closer.

Ill give this a shot. I was told there was were little to no wiggle room in moving the pads on the P5. Thanks

I do not have pictures or the measurements but I will work on getting that information posted as soon as i can. My fear is that I truly needed the 54 and made a mistake getting the 51.

If I recall correctly the headtube on the P5 is significantly taller than the old P2 design. Compared to the newer P2, they are very similar. (I haven't looked at the geometry charts in a while)

As far as the bike size goes, it will depend on how aggressive you run your bike. I ran the old geometry P3 very aggressive, and would have gone for a 51 P5 (5'10 with 74.5cm saddle height). However, if I wanted a little more relaxed geometry I would have gone 54.

So having a 51 P5 at your height is not necessarily wrong, but it will heavily depend on how you ride.

Ill get the measurements together tonight and post them. thanks

You may just need more stack due to the smaller frame. Are you running low v or high v?

Sorry to hijack this thread. I am looking at a P5 currently. Im going from a P3 (51) to a P5. I am fgoing for a fit to see what is best but am intereested in your views as to whether a 51 P5 is similar to the 51 P3?
Im 5ft6.....I feel the 54 will be too big but what are your views? Can the fit usually be replicated from a P3 to a P5?

Those stock 3T bars are simply not as comfortable as they should be. Elbows pads not as good as Profile (and others), and the particular shape of those ski bends is just a little off. So it could be differing setbacks or it could be brand of aerobars. Or a little bit of both.

Comfort in aero is the result of many converging factors, not all of which can be summed up by replicating "the distances from here to there".

NP3 and P5 have identical fits. At your size I wouldn't go bigger than a 51.