P2k and how the reversible seatpost affects fit

Triathlon Forum
1

as you probably already know (hope I’m not getting too boring, lol) I am seriously considering getting a 2nd hand 58cm p2k (6’0", 34 inseam, long arms and fairly flexible back) but am really, really, really worrying (probably too much from my own good, after all some years back all the ‘fitting’ I got was basically ‘check that the standing height is enough not to crunch your privates’) about whether it’s the ‘right’ size for me (as in, should I get a new 55 instead, despite the fact that the 2nd hand looks mint, has some component upgrades, costs less than the new AND it comes with a 404 wheelset).

I have been under the impression (by reading reviews of cervelo bikes) that switching the seatpost does not alter fit very much on the bike (say, if somebody fits on a p2k with the seat at 78, they’d still fit at 75), in my experience, though, when I tried sitting on this 58cm p2k, switching the seatpost did seem to make a difference: with the seatpost forward the bike felt just right (probably because according to the cervelo size the top tube length in this configuration is exactly the same as my current road bike’s) but with the seatpost back it felt just a tad more stretched out than I’m used to (not uncomfortably so, but noticeable none the less).

According to the website, though, the toptube length in the 75 configuration comparable to my road bike’s would be in the 52cm frame size (!) which I think would be far too small for my inseam (my road bike has a 56 top tube and is 57cm c-c).

I guess my question is really: should the p2k fit be the ‘same’ as my road bike in the 75 configuration and this would automatically translate to a ‘correct’ sizing/fit for 78 (regardless of how ‘strange’ it feels at first), or should I focus more on how it feels in the 78 position and not really care about things feeling the same in both seatpost scenarios?

I would like to go to a good local tri lbs (tri-action) this w/end and ask this type of fit questions in person (since they probably have 55 and 58 p2ks in store) but I’m really not sure on how to go about it in a honest/ethical way (I don’t want to take advantage of the owner’s expertise, but it feels hard to price such a conversation), after all if they told me the 58cm would work for me I wouldn’t buy it from them obviously.

2

Most shops will tell you that the size they have in stock is the size you need. This is particularly true with Cervelo and Felt as getting a new frameset that wasn’t ordered in a preseason order is nearly impossible.

My feeling is this - if you are going to ride steep, get the bigger size. If you will ride shallow, get the smaller size. Either frame size will probably work okay, but you will get better handling if you can limit the weight over the front wheel.

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I am 6’0 with a 34" inseam. If I were to get a P2k, it would be a 55, with the steep geometry. I could fit on a 58 with a really short stem, but I fit better on the 55. I wouldn’t bother with the shallow setup unless I was racing UCI sanctioned events or something…

4

Most shops will tell you that the size they have in stock is the size you need. This is particularly true with Cervelo and Felt as getting a new frameset that wasn’t ordered in a preseason order is nearly impossible.

While it may be true that some shops do this (though I would hope not), the reason you list here for Cervelo is not true. Virtually all framesets and bikes (even with Ultegra) are in stock in all sizes, at most with a 1-2 week wait. The only exception is the Dual, which can have a bit longer wait but even there we have them shipping out constantly. Thanks to our good friends at Shimano who really have been a big help this year, they don’t deserve the bad rap they’ve been getting lately. We have yet to see a shipment arrive late from them.

5

Ask if you can take the bike for a fitting, and leave a refundable deposit if (s)he has reservations about you taking off with the ride. Then call Greg and book a fitting. This way he is being paid for the service he will be providing you (to ensure optimal fit) and you are being honest about your intentions wrt asking which frame size works for you.

In my mind, this is the best way to achieve 100% peace of mind with your new purchase. Greg will also be able to inspect the bike/wheels for wear/warning signs that you might miss.