I am 5’11, of average build, and am looking to purchase a P2SL. From what I understand, I am right between a 54cm and a 56cm. Either size can probably be made to fit.
All else equal, is it better to go with the smaller size (54cm) or is it better to go with the slightly larger frame (56cm)?
Looking forward to everyone’s feedback/advice. Thanks in advance.
“Either size can probably be made to fit.”
Don’t take offense- none intended. The bike’s MSRP from the Cervelo website is $2500.
For $2500 don’t you want a fit that is a little better than “can probably be made to fit.”
Remember, the most important thing you can get for your $2500- more important than aero tubes, nice finishes or good looks is good bike fit.
Have you considered looking at something with dimensions in between the two frame sizes from Cervelo?
No offense taken…I appreciate your feedback.
Can you recommend something in between the Cervelo P2SL 54cm and 56cm?
Hard to say without seeing you positioned on the bike.
Anybody can be made to fit a variety of different sized bikes, but it’s the most optimum frame size that you want in order to achieve the best result.
Technically, I ideally fit between a 51 and 54 P2 frame, but am closer to the 54 so that’s were I went and have had no issues.
I’d let the shop help you decide, assuming that they are a good shop and understand bike fit.
Consider Tom’s advice that there may be another manufacturer’s bike that has a geometry between the two sizes you mention that might be more optimal for you. Of course this will take some research.
It’s very few people who genuinely need a custom fit. IMO, “custom fit” is a bit of a gimmick since it’s only people with unusual body proportions that can’t be fitted on a standard frame geometry. If by chance you are one of these people, Guru for example, will make you a custom frame.
Most people will likely tell you to go smaller, but I will go the other way and suggest going with the larger frame with a shorter stem. This way you get a longer front centre which will equate to a smoother ride and nicer handling in the 78 degree position.
I’m 5’6" and on a P3SL 53 and it fits pretty nice:
I have an 11 cm drop from nose of saddle to top of aeropads, but it does not show from this angle. Sorry for the non ST approved mismatched wheels…
Dev
Check if your lbs has both, take them to a certified bike fitter and he will let you know!
“suggest going with the larger frame”
In many cases that’s the better way to go, especially if you’re middle aged, MOP or have flexibility issues…
The “go to as small a frame as possible” or “get as low as possible” is bad advice in many cases.
"especially if you’re middle aged, MOP or have flexibility issues… "
Of course Dev, I was referring to myself. Not you. 
“I will go the other way and suggest going with the larger frame with a shorter stem. This way you get a longer front centre which will equate to a smoother ride and nicer handling in the 78 degree position.”
yessssss!!! bingo.
My first thought was to maybe come up with how you would like the Cervelo geometry to be different. would you like a longer top tube? Would you like the head tube height from the 56cm frame but the effective top tube length from the 54cm frame at the 78 degree orientation?
If you can nail down where you would like the dimensions to fall ideally between the two bikes then you can use those dimensions as your shopping list to evaluate other frames. There are so many out there, almost all of them quite good.
An additional resource is to call Robert P. at Guru Bicycles, David G. at Elite Bicycles and Ves at Yaqui. These three fellas can built you a bike to your spec in a short time. Guru is running four weeks on custom geometry with no upcharge for custom. Tell Robert how you want your bike to be- complete with color- and four weeks later you are on the perfect dimensions as specificied by you. Same goes for Ves and David Greenfield at Elite, who is quite a fine man.
Best of luck on this. Please check back on the forum and let us all knw how it shook out.
Doesn’t the p2sl come in 55cm? That’s actually why I got a p2sl last season - the p2k only came in 54/56, but I fit better on a 55 and the p2sl came in that size.
Oh, I just looked on the Cervelo site and it doesn’t look like it does anymore. Maybe you could find a 2005 model?
Cervelo made a limited run of 55cm black annodized frames mid last year. You got one of those. It is a rare bike. You shouldn’t have crashed yours.
I think either bike can be made to fit fine (and there is nothing wrong with adjusting bikes to make them fit)
hmmm… I don’t know how much you read this forum, but people are pretty fit-obsessed here. I think a lot of the responses assume that you’ve had a whole bunch of measurements done, know your inseam and your femur lenghth and the distance from your knee to your greater trroncanwhatever… and that, given all those measurements, you fall somewhere right btwn the two sizes. if that’s so, then you’ve gotten the answers that are appropriate.
my read of your OP, though, was that you just had a general sense that either could work, and didn’t know which way to go. If that’s so, then you should consider figuring out what your measurements are; if you post them I think a lot of the fit gurus on this forum could give you a good estimate - it could be that yes, you’re btwn the two sizes, but significantly closer to one of them.
there are some on-line fit calculators that will tell you what measurements you need to make. (someone else may have the appropriate links, i’m not at my home computer).
-charles
“I will go the other way and suggest going with the larger frame with a shorter stem. This way you get a longer front centre which will equate to a smoother ride and nicer handling in the 78 degree position.”
yessssss!!! bingo.
Thank God for some sensibility… yessssssssssss toooooooooooo!!!
One point to note is that this approach is only possible with a few brands. Most brands have the head tube grow substantially in the larger frame sizes as the top tube increases. Not so with Cervelo. My 53 P3SL has a 90 mm head tube. I actually have a 120 mm stem with minus 10 degree rise (so it works out to plus 7) with a 5 mm spacer. I really fit more like a guy who is 5’9" - 5’10" on my bikes given my longer arms and longer legs (ie chimpanzee factor…)
I could go lower, and more aero, but I’d be unable to hold the aero position riding into a 20 mph headwind up a 2-4% grade. To me, if I can’t do this, and have to sit up, my aero position is too low.
In any event, if you can find a frame with a low front end (relatively for the frame size), having the longer front centre is very nice. Also keep in mind that some bikes barely even grow their front centre with frame size…just the seat tube and head tube increase in height (but this is rare).
Dev
“Most brands have the head tube grow substantially in the larger frame sizes as the top tube increases.”
yes. and many of them also have the top tube grow unreasonably long as well. even better is to employ this on cervelo’s P3C, with a SMALLER head tube than its (already sufficiently small for most people) P2C and SL.
best, of course, to figure out what your optimized points in space are and transfer them onto a bike you already know will accommodate them.
Dan of course is right in that you really need to find your contact points and then transpose them to a particular frame. i.e., you want to avoid a 5cm or 150cm stem or 8cm of shims under your stem. With a smaller frame you may be WAY too low in front short of excessive shimming. The bigger frame may have too long of a cockpit. It all depends on a myriad of factors. I came up w/ a big spreadsheet to do all these calcs. It of course assumes you know where your contact points should be, which is another issue.
Excuse my ignorance.
If you go up rather than down don’t you run into a lack of drop issue. Because of my short inseam (29.5) and long torso, I’m on a 56 Soloist, which is great. But I’ve started with zero drop with only about a cm of stem to play with. Or is there some other way of progressing to a lower front end ?
You could get a negative rise stem.
I would say that if you have a 29.5 inch inseam, and a long torso, the Soloist probably isnt the optimal bike for you. A 56cm trek OCLV has the same top tube length, but is 2 cm shorter at the head tube.
Now that that is out of the way, you can always go with a Look ergostem or ITM /Ritchey adjustable stem. Those will allow you to achieve pretty much any position you want.