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Cervelo P2C Fit/Size Question
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Hi everyone, this is my 1st post on Slow Twitch or any online forum; so please be nice, lol!

I’m sure this question has been asked (YES, I have searched for an answer, but I would like some more personalized advice), but I have an opportunity to get a really amazing deal on a Cervelo P2C 54cm. My question is: Is a 54 too big?

I’m 5’-7” barefoot, proportional torso to legs and arms. I am flexible and ride aggressively.

I am an engineer and I put my body dimensions and both a 51cm and 54cm bike into CAD. From what I can determine, I can make both bikes work. It appears that I have the options to make the 51cm larger/longer or make the 54 smaller/shorter, but I’m no expert. I am going to get a fitting done once I get a TT/triathlon bike.

What I’m looking for you all is: advice, opinion, suggestion. Someone please steer me in toward the correct frame.

- CaliRob

P.S.: By the way, I currently ride a Cervelo Team (S1) 54cm in both the tri position and traditional road position. Both positions work and feel fine. Getting a fitting on that next week!
Last edited by: CaliRob: Apr 7, 10 10:54
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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In Reply To:
Hi everyone, this is my 1st post on Slow Twitch or any online forum; so please be nice, lol!

I’m sure this question has been asked (YES, I have searched for an answer, but I would like some more personalized advice), but I have an opportunity to get a really amazing deal on a Cervelo P2C 54cm. My question is: Is a 54 too big?

I’m 5’-7” barefoot, proportional torso to legs and arms. I am flexible and ride aggressively.

I am an engineer and I put my body dimensions and both a 51cm and 54cm bike into CAD. From what I can determine, I can make both bikes work. It appears that I have the options to make the 51cm larger/longer or make the 54 smaller/shorter, but I’m no expert. I am going to get a fitting done once I get a TT/triathlon bike.

What I’m looking for you all is: advice, opinion, suggestion. Someone please steer me in toward the correct frame.

- CaliRob

P.S.: By the way, I currently ride a Cervelo Team (S1) 54cm in both the tri position and traditional road position. Both positions work and feel fine. Getting a fitting on that next week!

It depends really on how you want to ride the head tube is taller on the 54 so you will be able to sit up higher. I would go get on a bike shop and see how they both feel.

For instance i'm 6'0 and the next cervelo tt bike i get will be a 51 because a 54 is too long.
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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As was mentioned above, the best way to find out is to go to a bike store and try them out. I am 6' and ride a 54 P2C.
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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Calirob,

FWIW - I am also 5'7" with a 30" inseam. I have been comfortably riding a 51cm P2C for three seasons and couldn't imagine riding a bigger bike because this one fits me so well.

Cheers,

Dave


Dave Stark
dreamcatcher@astound.net
USAC & USAT level 2 certified coach
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Re: Cervelo P2C Fit/Size Question [karsten] [ In reply to ]
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Yes... I have to agree. It's more then worth your time and money to go in a get a proper bike fit from a professional. This will also probably improve your performance more then all the "aero" accessories (wheels helmet etc.) you can buy. Once you have your "Fit Coordinates" you should be able to determine if the 54 (or any bike for that matter) can be adjusted to fit you.
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Re: Cervelo P2C Fit/Size Question [draketriathlon] [ In reply to ]
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6' and wanting to ride a 51 P2C. Are you sure the long and low Cervelo is your best fit? Going from the 54 to a 51 means you are going to need 3cm more stack/spacers. I would think something like a 54 Slice may be worth considering since it will be close to the stack of the 54 p2c and the reach of the 51 p2c. Just my 2cents.
-Tim
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Re: Cervelo P2C Fit/Size Question [TimBikeToo] [ In reply to ]
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Wow...thanks for the fast responses...much appreciated.

A friend told me to try the competitive cyclist calculator. This is what it spit out:

Measurements
-------------------------------------------
Inseam: 32
Trunk: 24
Forearm: 13.25
Arm: 24.5
Thigh: 23
Lower Leg: 21
Sternal Notch: 54.5
Total Body Height: 67.25


The Aero Fit
-------------------------------------------
Top Tube Range: 49.7 - 51.7
Stem Length Range: 8.0 - 10.0
Saddle-Bottom Bracket Position: 73.2
Saddle-Pedal Position: 90.4
Saddle-Ground Position: 98.2
Cranklength: 172.5
Aero Bar Size: M
Saddle-Aero Bar Pad Drop Minimal: 4.8
Saddle-Aero Bar Pad Drop Moderate: 9.9
Saddle-Aero Bar Pad Drop Intense: 12.1
Saddle-Aero Bar Pad Drop Maximal: 15.8
Pad-Ground Position Minimal: 93.4
Pad-Ground Position Moderate: 88.3
Pad-Ground Position Intense: 86.1
Pad-Ground Position Maximal: 82.4

Comments?
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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I would think the 54 would be way too big for you. Yeah, you could make it work, but it would still be the wrong size.
You should be on a 51, unless you have -really- abnormally long inseam and arm length for someone your height...
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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I'm 5-6.5 and ride a 51cm P2C. I did purchase the bike used from someone who was 5-9 (she was all legs and had a very long seat post). Prior to purchasing, I tried out the 54 at my LBS. The 54 was WAY too big - I can't remember what the exact fit problems were but, end of the day, it was too big. Even if the bike is a great deal, you'll have to spend additional money trying to get the bike to fit you better and, most likely, it never will fit you quite right. That said, its not worth the price, no matter what it is -- you'll just end up getting something different later on.

Here's some food for thought (my measurements from competitive cyclist - which are similar to yours):

Measurements
-------------------------------------------
Inseam: 30.5
Trunk: 24.75
Forearm: 12.25
Arm: 24.25
Thigh: 22
Lower Leg: 20.25
Sternal Notch: 55.5
Total Body Height: 66.5


The Aero Fit
-------------------------------------------
Top Tube Range: 52.5 - 54.5
Stem Length Range: 8.0 - 10.0
Saddle-Bottom Bracket Position: 69.7
Saddle-Pedal Position: 86.9
Saddle-Ground Position: 94.7
Cranklength: 172.5
Aero Bar Size: S
Saddle-Aero Bar Pad Drop Minimal: 3.4
Saddle-Aero Bar Pad Drop Moderate: 8.3
Saddle-Aero Bar Pad Drop Intense: 10.4
Saddle-Aero Bar Pad Drop Maximal: 13.8
Pad-Ground Position Minimal: 91.3
Pad-Ground Position Moderate: 86.4
Pad-Ground Position Intense: 84.3
Pad-Ground Position Maximal: 80.9
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Re: Cervelo P2C Fit/Size Question [roxiegirl] [ In reply to ]
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Yeah, I think all are correct. The 51 does sound like the better fit and I do want a steep seat tube angle. That's why I'm looking for a specific Tri/TT bike. I wasn't getting aggressive enough on my S1 for my wanting.

Ok, now for another question. I do have an option of picking up a 52cm Cervelo P3 Aluminum 650c off CL in my area. Am I degrading the bike too much (in my mind) because of the 650c wheels? I haven't seen it yet, because no pics were posted, but they want $425 for the frame! I know 650c wheels are still available and frames are still made with them, but am I over analyzing?

I hope I'm getting my point across and not rambling. Let me know if I need to be more clear. Thank you all very much!
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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5'10" on a 54cm P2C and wishing that I was on a 56 with a 10cm stem and an Adamo saddle in the rear seatpost hole, all the way forward on the rails. Running somewhere between 4.5" and 5" of drop from the saddle to armrests.

I wish that I was on a 56 because I would like a longer cockpit to make it easier to ride a more forward position. I choose a 54 several years ago because that was the size of my road bike.

Old school (and I am old) thinking was to ride a TT bike in as small of a size as possible with the idea that smaller frame = more aero and stiffer. These days that's not necessarily the case and a larger bike can be faster in some cases e.g. on a bike with a shaped, aerodynamic head tube (Cervelo P2/3/4 for example), the hourglass head tube shape is more aero than the spacers around the steer tube so a 56cm frame with no spacers under the stem will be more aero (minutely) than a 54 with 2cm of spacers. Also the larger bike has a slightly longer wheel base which should make it easier to track a straight line. I would assume that a well made carbon frame doesn't give up much stiffness going from a 54cm frame to a 56cm frame.

If someone was truly between frame sizes and could obtain the desired amount of drop and reach on either frame without resorting to extremely long or short stems, I would tend to recommend the larger frame rather than the smaller
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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I'll probably get flamed for this but...

Why do you want 650 wheels? All antidoctal thoughts but of the 5-6 people I know that have them, all but one wish that they had 700s.
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Re: Cervelo P2C Fit/Size Question [roxiegirl] [ In reply to ]
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That's my dilemma as well. I know the engineering and numbers aren't enough to distinguish a clear winner between the two sizes. It isn't that I want 650 wheels. It is that the frame is the right size and price is amazing! We enginer-nerds are frugal!

One more thing..."Flamed out"? Eh? What? Who?
Last edited by: CaliRob: Apr 7, 10 12:26
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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I'm a shade over 5'8" and ride a 54cm P3 it fits perfectly - I WAS previously on a 51cm P3 alu and had to go to a 120 stem to get the fit just right. The way cervelo sizes their bikes means that you should pick the same size as your road bike - but i'd suggest you're on a road bike that's maybe a size too large. I think the 51 will be just right for you as a larger size will have a taller head tube and prevent you from getting that more aggressive position you're looking for.

Regarding the P3 Alu w/ 650's ... I loved mine. However, the P2 will be just as fast, quieter, and you'll have waaaaaayyyy more choices for wheels, tires and tubes. Of course, you'd be able to pick up a nice set of used race wheels for 50% of what they'll run you in 700 ... but I don't think that ends up being an even trade. As much as I like 650's they really seem to be going away.
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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Because I'm a mere mortal on the slowtwitch boards... (i.e., my average bike speed is less than 20 mph, my marathon PR is a 4:15, and my IM time is a 13:57 -- which I was VERY happy about).

There are a lot of knowledgable people on these boards and a lot of very good athletes. You also have people like me who have learned things through experience but is also a lot slower and probably more recreational than some of the other folks on here. There are a lot of people who take things very seriously... (which is why you can get a lot of good free advice)
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Re: Cervelo P2C Fit/Size Question [JollyRogers] [ In reply to ]
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the old school was off a bit ... long stems and seat posts add more weight and wiggle to your bike than a slightly larger frame. The longer the stem and post, the longer the lever is to act on the mechanical joint which is not nearly as strong as the tube junctions.
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Re: Cervelo P2C Fit/Size Question [TomNYC] [ In reply to ]
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This might be a dumb question, so feel free to correct me.

Is it possible to swap fork for 700c wheel and does the horizontal dropout have enough play/room to accommodate a 700c wheel?
Last edited by: CaliRob: Apr 7, 10 13:04
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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uhh ... no, I'd say not.

If your choice is between a P2 and a P3 alu - they are both fast bikes. The carbon one will be a bit quieter and allow you a greater selection of wheels and tires in the 700 size. But the P3 is great in aluminum - I'd be riding mine happily still if it hadn't been stolen. If you want to go that way - go for it ... BUT trying to engineer your way out of a problem that's not really a problem will make for a sub-optimal result.

650's on a P3 aluminum will be plenty fast, though aerodynamically speaking, the P2 is the equal or a bit better than the P3 alu.

If it's a cost thing and you want the P3 get it and don't worry about the 650 issue - there are enough around.
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Re: Cervelo P2C Fit/Size Question [TimBikeToo] [ In reply to ]
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In Reply To:
6' and wanting to ride a 51 P2C. Are you sure the long and low Cervelo is your best fit? Going from the 54 to a 51 means you are going to need 3cm more stack/spacers. I would think something like a 54 Slice may be worth considering since it will be close to the stack of the 54 p2c and the reach of the 51 p2c. Just my 2cents.
-Tim

Plus 1.

I made the mistake of buying a P2c... then having the bike fit.
The result was me buying another frame that actually fitted me.

Get the bike fit... then the bike
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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I had a fitting with a LBS. They ordered a 56 P2C. A 58 came in. LBS convinced me that either size would work. So I took the 58. I am 6' but have a 35.5" inseam measured by LBS. When I measure I get 35".

Ultimately I purchased a 56 in addition to the 58. The issue with purchasing a P2c that is too big is that you can only go so low on a P2C. So even if you start riding a little higher and want to work your way lower. Or you want to do shorter races lower and longer races with a bigger stack a P2C will limit what you can do.

Sure you can use different stems but I prefer to use one and move depending on length of race.
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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You are almost the exact same dimensions as me. You have a little longer legs but a bit shorter torso. Anyway, I went and got fit and now ride a 51cm P2c. Fits GREAT!!!
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Re: Cervelo P2C Fit/Size Question [bartturner] [ In reply to ]
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In Reply To:
I had a fitting with a LBS. They ordered a 56 P2C. A 58 came in. LBS convinced me that either size would work. So I took the 58.



Is this the lbs that starts with a "P"? That's VERY poor.


Steve

"If you ain't first, you're last." Reese Bobby Talladega Nights
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Re: Cervelo P2C Fit/Size Question [The_Mickstar] [ In reply to ]
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Overall I been very happy with the LBS besides this situation. He ultimately gave me the choice to send back the 58 when I came in to pick it up. Telling me either would work and I choose to keep it. Well for a couple of weeks.

Ultimately I think everyone should learn how to do their own sizing. That is what I do now. There is so much tweaking that is really necessary. Based on how long is the race, where you are at in the season, comfort, power, aero. I made some changes and rode last night and the changes were perfect getting ready for New Orleans next week. I was having some comfort issues. So improved comfort and power. Lost some aero, I believe. Also improved on some knee pain. I have to play around with my fit based also on some knee pain versus a hamstring issue.

I am also now learning to do my own wrenching. Which I am really enjoying and learning a ton. So far it has been easier than I thought it would be.
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Re: Cervelo P2C Fit/Size Question [bartturner] [ In reply to ]
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In Reply To:
Ultimately I think everyone should learn how to do their own sizing. That is what I do now. There is so much tweaking that is really necessary. Based on how long is the race, where you are at in the season, comfort, power, aero. I made some changes and rode last night and the changes were perfect getting ready for New Orleans next week. I was having some comfort issues. So improved comfort and power. Lost some aero, I believe. Also improved on some knee pain. I have to play around with my fit based also on some knee pain versus a hamstring issue.

I am also now learning to do my own wrenching. Which I am really enjoying and learning a ton. So far it has been easier than I thought it would be.

Could not agree more... I'm about 6-1, 34" inseam, and ride a 58 P2C. I have my saddle position pretty well dialed in, but still shuffle the spacer/stem stack at least 3-4 times each season (coming up on season 3 now with that frame) depending on the situation.
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Re: Cervelo P2C Fit/Size Question [OneGoodLeg] [ In reply to ]
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I'm 6'5", not too leggy, and ride a 61 P2C. But I got sized and glad I did because with just a saddle and handlebar adjustment I avoided getting a bike that was to big for me
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Re: Cervelo P2C Fit/Size Question [bartturner] [ In reply to ]
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I read this forum a lot before purchasing my P2C. It was the first tri bike had ever ridden. My impression from the forum was that fit was some exact science. People strongly recommend to get a fitting done. I was surprised when I did the initial fitting I was asked several times how does that feel? I thought they would measure me and then set the bike exactly a certain way.

I am not saying do not get a fit but learn everything you can during the session. Keep your measurements, bike and your body. I now log all the changes I make to the bike with also some scoring of what the change seemed to do in the way of power, aero and comfort. It is not perfect but more of a feeling. The one that is really tough is aero. I have been doing some tweaking lately but it has been so windy here that trying to see any aero consequences is impossible.
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Re: Cervelo P2C Fit/Size Question [bartturner] [ In reply to ]
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I needed a bike for upcoming IM St. George. I'm almost 6 foot even, but i found a deal on a 58 p2c cm that i couldn't pass up. Im worried now that it is just going to be too big for me, how much of a difference is a 56-58 going to make, and should i look to buy/trade to a 56 frame? Thanks sorry for thread Hijack
Last edited by: sparta070: Apr 11, 10 19:45
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Re: Cervelo P2C Fit/Size Question [sparta070] [ In reply to ]
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Can't say one way or the other on the 58 vs 56 without more info; saddle hieght is a non-issue since the difference falls well within the range of seatpost adjustment, so the issue is the front end... 58 is I think 1.5 cm longer on the top tube and 2 cm taller on the head tube, thus you need to figure out how low you want to go vs how much forward reach is comfortable in the aerobars. The choice of basebar and aerobars will also have an effect on the elbow pad position, so it's impossible to give a set answer as there are too many potential combos.

Using my example, I felt the 56 would be too low in front, so I got the 58 and went with a shorter stem (90mm). That's a little on the short end for stems, which can begin to affect handling, so you should shoot for something in the 100mm ballpark. If you need a 70mm stem to keep from reaching too far forward, you should consider a smaller frame, or if you need a 3-4 cm stack of spacers under the stem, then you ought to look at a bigger frame. If you need both a shorter stem and more spacers, then Cervelo's geometry is probably not for your body type; there are other brands that offer shorter top tubes relative to the head tube for each size ("reach" vs "stack" in ST parlance).
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Re: Cervelo P2C Fit/Size Question [JollyRogers] [ In reply to ]
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In Reply To:
5'10" on a 54cm P2C and wishing that I was on a 56 with a 10cm stem and an Adamo saddle in the rear seatpost hole, all the way forward on the rails. Running somewhere between 4.5" and 5" of drop from the saddle to armrests.
I wish that I was on a 56 because I would like a longer cockpit to make it easier to ride a more forward position. I choose a 54 several years ago because that was the size of my road bike.

x2 - this is identical to my story. I bought a 54cm P2 and now am wishing I went 56cm. I've just put a 120mm stem on mine just to stretch the cockpit out. I'm 5'10" with 33" inseem.

Anyways 5'7" - if your torso is long enough or you go with a 70-90mm stem - you may be ok.
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Re: Cervelo P2C Fit/Size Question [CaliRob] [ In reply to ]
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here's a nice article dan wrote about this very topic:

http://www.slowtwitch.com/...ike_sizes__1173.html

FWIW, i'm just a bit taller than you and test rode a 51 P3C at IMAZ last year. it felt like a perfect fit with an 80 stem and the stock vision bars (low stack). could i ride a 54? possibly but i know the 51 felt great and there was only 1 spacer on it.

shifting gears, cervelo only made alu P3's in 48, 51, & 54cm so check the head tube length if you go that way. i have a 650 P3 and i like it very much (ridiculously good deal off CL, guy bought for his wife and she rode it 3x before she decided she liked her old bike). in the wheel stable there is at present both zipp & hed discs, zipp 404's & 303's and i got ALL of them used off fleabay for less than the price of ONE 700c zipp disc. sure you're limited with your tire/wheel choices but if you watch ebay/ST classifieds people practically give away 650 gear. something your "frugal engineer-nerd" side may want to consider.

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Michael in Fresno
"Do you spend time with your family? Good. Because a man that doesn't spend time with his family can never be a real man" V. Corleone
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