Official FIT ASSISTANCE for Cervelo TT and Triathlon Bikes

[ericMPro]

Eric - Many many thanks. My bike fitter is Retul certified and well known (I am sure you know him). He has said the P4 has limitations and based on everything (bike adjustability, body, cranks, etc) my fit is best outcome. So you both are matching in thoughts (great minds think alike). I like this forum so wanted to check with you. I am traveling, Northwoods Country Inn with wife, and will drop you some pictures in a few days. Thinking cranks…Shimano makes a 165mm but nothing shorter that I have seen. Given my 5’7”” frame do you like a manufacturer that makes a shorter crank that works with Di2? Thanks again…

your fitter is right, the P4 is definitely limited. Fast bike though. I raced it for one IM cycle, attempting to qualify and then qualifying for Kona. I felt like my bike split was up there both with my peers’ time and also good based on the watts I put out. I had the rear brake all the way loose, and only for emergencies, and was very cognizant of the fact that it might be rubbing when I used it. I had the P4 bottle cut out to use as a flat kit, and I had to do some work with the front end, despite being sort of long and low, because the P4 frame is very long and low. I have another one now, and it’s equipped with the TriRig Alpha One and it’s glorious. Only used for sprint and olympic races and open TTs.

There’s a loose correlation between height and leg length and leg length and crank length, but I’ve also seen plenty of “short” people handle “long” cranks and plenty of “tall” people need “short” cranks. You may be fine w/ 165mm, the lowest easily available length, but at your height I’d almost certainly want you to try 155mm at the very least.

Any crank, with the right bottom bracket for the crank’s spindle diameter and your frame’s BB shell width and inner diameter, will work with Di2 AFAIK. Most of my clients who end up on short cranks end up on Cobb alloy cranks and power pedals (Garmin, Assioma), as that’s the cheaper alternative to some of the crank based 160mm and below power meter crank combos. Cobb has 24/22mm spindle, ie. SRAM GXP, so you get the right BB for your frame and install the Cobb crank. For the P4 that would be a threaded external BB for SRAM GXP IIRC.

I actually have a Ceramic Speed threaded external BB for GXP if you go that route.

Eric

[ericMPro]

Shimano does have the 105 R7000 crankset in 160 mm.

Jeroen

thanks for that!

[DMVD]

Eric

I agree, my P4 is zippy (we know the rider helps a bit) and carried me to a 70.3 Championship race a few years ago. Only issues I have had is, like you, rear brake rubbing, and my seat post shrunk in a 70.3 race when I hit a poorly maintained small bridge bump.

Thinking about the 155 cranks…creates another issue which is what size chain ring should you move to? My current SRAM Red is 53/39. Again, many thanks to get an unbiased opinion.

[ericMPro]

Eric

I agree, my P4 is zippy (we know the rider helps a bit) and carried me to a 70.3 Championship race a few years ago. Only issues I have had is, like you, rear brake rubbing, and my seat post shrunk in a 70.3 race when I hit a poorly maintained small bridge bump.

Thinking about the 155 cranks…creates another issue which is what size chain ring should you move to? My current SRAM Red is 53/39. Again, many thanks to get an unbiased opinion.

I usually select the largest chainrings possible.

I sort of use the same couple of gears for all races… 75rpm for IM, 80rpm for HIM, 90rpm for OD, 95rpm for Sprint, etc., and I have enough power to get up the steepest climbs in the 28t cog, so big chainrings and a straight chainline are feasible for me. If you ride IM at 100rpm you might want to reconsider.

[kjohn]

Hi,

I am looking to purchase a P5d since my P2 is stuck in storage in USA and I am overseas right now. (Good excuse to buy a new bike, right??) My P2 is a 56, but local fitters have suggested that I am in between 54 and 56 so both would work. Other fitters say definitely a 54.

Here are my measurements from my GURU DFU fitting:

Saddle height: 73.5
Setback -1.5 cm
Pad stack 650
Centerpad reach 475 (back of the pads was 415? I am not sure about this)
Bar reach 460

Background: After a hip tear and moving for work, I have not done any cycling in almost 2 years (IM, HIM). Hoping to build back up to racing soon

What do you suggest?

[ericMPro]

Hi,

I am looking to purchase a P5d since my P2 is stuck in storage in USA and I am overseas right now. (Good excuse to buy a new bike, right??) My P2 is a 56, but local fitters have suggested that I am in between 54 and 56 so both would work. Other fitters say definitely a 54.

Here are my measurements from my GURU DFU fitting:

Saddle height: 73.5
Setback -1.5 cm
Pad stack 650
Centerpad reach 475 (back of the pads was 415? I am not sure about this)
Bar reach 460

Background: After a hip tear and moving for work, I have not done any cycling in almost 2 years (IM, HIM). Hoping to build back up to racing soon

What do you suggest?

hi there, thanks for reaching out.

Your local fitters are right, with a Pad Stack of 650mm and a Pad Reach of 425mm you are a 54cm P5d, but just barely. Very upper left quadrant of the fit chart, in other words very upright and very slack. Seeing these numbers would make me question the orthodoxy of your basic fit, and also make me wonder where your fit might progress toward if it’s not totally locked in and perfect now.

At that stack height, you have up to 470mm of reach in a size 54cm P5d before the reach runs out. You’d have 77mm of a possible 88mm of mono-riser exposed.

To fit a 56cm P5d, you’d need to be at a minimum pad reach of 437-442mm, or another 12-17mm from where you are now, which isn’t much.

A 54cm P5d will work. You’re not in dire need of a 56cm or in danger of running out of room on the 54cm, but it’s something to consider.

Make sense?

[kjohn]

I see what you mean. He measured from the center of the pad (475) instead of the back because he said that it should be more representative of my reach because the pads vary in size. When he measured the back of the pad, he came up with 415 which is not on the chart??

Since, I have been out of triathlons for about two years now from a hip tear, I am essentially starting over. I believe that my fit process is definitely not perfect at all and should progress a quite a bit. I worry that if I buy a 54, I will end up wishing I bought a 56.

I spoke to another fitter about scheduling something soon. He said that since I am 180cm, I’m probably on the border of 54/56, but he seemed pretty confident that a 56 would be in my best interest because of a hip tear (with the included lower back pain). He suggested that although a 54 may allow a more aggressive position, a 56 will be more comfortable for longer formats? So, I guess that’s next on my to-do list.

I live in Thailand and the weather is unbearably hot, humid, and rainy so my goal is to do mainly Oly/HIM races and primarily train indoors with the occasional outdoor cycling tracks (open roads are extremely dangerous here…lol)

I appreciate all your advice! Thanks

[ericMPro]

I see what you mean. He measured from the center of the pad (475) instead of the back because he said that it should be more representative of my reach because the pads vary in size. When he measured the back of the pad, he came up with 415 which is not on the chart??

Since, I have been out of triathlons for about two years now from a hip tear, I am essentially starting over. I believe that my fit process is definitely not perfect at all and should progress a quite a bit. I worry that if I buy a 54, I will end up wishing I bought a 56.

I spoke to another fitter about scheduling something soon. He said that since I am 180cm, I’m probably on the border of 54/56, but he seemed pretty confident that a 56 would be in my best interest because of a hip tear (with the included lower back pain). He suggested that although a 54 may allow a more aggressive position, a 56 will be more comfortable for longer formats? So, I guess that’s next on my to-do list.

I live in Thailand and the weather is unbearably hot, humid, and rainy so my goal is to do mainly Oly/HIM races and primarily train indoors with the occasional outdoor cycling tracks (open roads are extremely dangerous here…lol)

I appreciate all your advice! Thanks

a few things that pop out:

1. yes, 415mm would be off the charts to the left, ie. not enough reach to hit the minimum reach for the 54cm. One thing to mention is that you could use the EX-10 mono-riser from the P3x on the P5d and add a little reach flexibility that way. That said, I don’t really think you need that little reach, even though I’ve never seen a picture of you on the bike. With proper postural coaching you can hit the minimum reach for the 54cm or even the 56cm.

2. I’m immediately triggered when I hear your fitter saying that the 54cm “may allow a more aggressive position”, for two reasons. First, your position is your position, and it will be the same on either bike, assuming it’s achievable on both bikes. Second, “aggressive” is a buzzword red flag for me, ie. there’s no such thing. Positions are either orthodox or they’re not, they’re either optimized or they’re not. Aggressive and/or conservative are nonsensical words that make no sense here.

3. I’m also triggered by the logic leap from “conservative” to “being better for long course”. There’s very good reasons for getting longer and lower, and one of them is that if done right, you actually make yourself more comfortable and more efficient for longer rides. Part of it is getting weight onto the front end and off of your pelvis, but there are other factors as well. At any rate, “more comfortable for long course” is code for “I don’t understand long course bike fitting” so be careful.

Finally, seeing as how you are in Thailand, I’m confident that if you purchased a 56cm P5d and we did a remote fit together, I could get you in the right place. Or another competent remote fitter. It’s all about saddle choice and coaching about how to sit on it and then postural coaching for the rest.

Finally finally, I’d be curious to see how different crank lengths affect your repaired hip, and have a hunch that shorter cranks and thus smaller range of motion might be better for you. Something to think about.

Eric

[theviens]

Hi Eric,
Thanks for doing this. I enjoy reading your analysis on everyone.

I have been riding the same bike since I got in the sport 6 years ago (QR CD.01). I bought it because it was a good deal and probably not the best fit for me. When I had it fit, the fitter says it was long for me (5’7, 145lbs). I also have a bad lower back. We have it stacked and stemmed up for those issues. Definitely not the most aero. But I feel comfortable on it. I tried the P5D which I loved, except for the base bar. I felt very limited climbing with it that low, it will probably irritate my back, and it does not seem to be able to rise. The P series looks better and more adjustable for me. I tried a 51 and it felt awkward. I may need a 54? Would I be better of just getting the frame and customizing for fit of cockpit and crank lengths for example? I have tried to attach my retul fit and a picture of me riding. What is a remote fit you mention in a few posts? Thanks for the thoughts, time and recommendations. I am ready for a new bike! Todd

QR CD.01 Retul.pdf
Bike.pdf

[ericMPro]

Hi Eric,
Thanks for doing this. I enjoy reading your analysis on everyone.

I have been riding the same bike since I got in the sport 6 years ago (QR CD.01). I bought it because it was a good deal and probably not the best fit for me. When I had it fit, the fitter says it was long for me (5’7, 145lbs). I also have a bad lower back. We have it stacked and stemmed up for those issues. Definitely not the most aero. But I feel comfortable on it. I tried the P5D which I loved, except for the base bar. I felt very limited climbing with it that low, it will probably irritate my back, and it does not seem to be able to rise. The P series looks better and more adjustable for me. I tried a 51 and it felt awkward. I may need a 54? Would I be better of just getting the frame and customizing for fit of cockpit and crank lengths for example? I have tried to attach my retul fit and a picture of me riding. What is a remote fit you mention in a few posts? Thanks for the thoughts, time and recommendations. I am ready for a new bike! Todd

When another fitter says says a bike is too long for someone, I usually start salivating at the thought of someone being on a properly sized bike! Let’s have a look…

Looking at your bike fit photo, you seem upright and a little slack, IOW you’re not taking advantage of the longness and lowness of the QR CD.01. This could be for a number of reasons, not least of which it’s an oblique angle photo and not the best perspective, but perhaps it’s because you haven’t had the postural coaching and saddle choice coaching that would enable you to do what a time trial allows you to do with your body. Even with a bad lower back (which I have as well), you can get into a reasonably orthodox and aero position if you keep your back neutral and roll your pelvis forward instead of bending your lower back to get to where you need to go. This effectively lengthens your upper body, and thus long and low frames come in handy when you have this posture. The key is the saddle, and how the aerobars catch you.

With a Pad Stack of 682mm and a Pad Reach of 411mm, your current Retul fit numbers, you’re an odd duck, something is up. Very upright or high Pad Stack for someone of your height. Off the charts high for a 51cm P5d and off the charts high and left (ie. slack) for a 54cm P5d. You’re even too high for a 56cm.

I hear you about the lower back issues, and I hear you about the basebar, but I feel like putting a band-aid on those problems is a side issue, and we need to get to the root of the issue, the cause of what’s going on. There is no reason why a lower back challenged person (remember, me included) can’t have a good TT position with the right saddle choice and sitting and postural coaching. I’m also not buying the theory that the P-Series is more adjustable or more appropriate for you, not for the reasons you’re giving. Follow me here…

For example, if you came down 2mm to 680mm and added 22mm (not even an inch) to your current position, you’d hit the very upper very left quadrant of a 56cm P5d. This is very easy to do, just with posture, and if you slid your saddle forward to help out it’s even easier.

To hit a 54cm P5d, the very upper left quadrant, you’d need to lower your Pad Stack to 662mm (18mm, again less than an inch), and add 7mm of reach to 418mm, which is barely even noticeable. Between the two options, ie. adding an inch of reach to hit the 56cm P5d or subtracting an inch of stack to hit the 54cm P5d, the reach is an easier as, unless you went with shorter cranks in which case it would be a wash.

At any rate, after my hypothetical adjustments to you here, you’re still at the very upper very left edge of the fit charts, for either a 54cm or 56cm P5d, and that’s not something I would call orthodox. You’ll be the same on a P-Series. Let’s address your fit first and your orthodoxy and see if we can’t crack the code on the saddle in order to get your back in a neutral posture effectively lengthening you and lowering you. The more I think and write about it the more I think short cranks and a saddle intervention and postural coaching are what you need.

(I should add here that a EX10 mono-riser from the P3x is something you certainly should do, it adds some reach flexibility fore and aft as well as a native tilt function, which will help you)

Finally, stay away from a 51cm bike at all costs.

Make sense? Shoot me a PM and we can talk more or I can find you a fitter. If I had to go with my gut I’d say get the 54cm P5d with the EX10 tiltable mono-riser.

Eric

[kjohn]

I see what you mean. He measured from the center of the pad (475) instead of the back because he said that it should be more representative of my reach because the pads vary in size. When he measured the back of the pad, he came up with 415 which is not on the chart??

Since, I have been out of triathlons for about two years now from a hip tear, I am essentially starting over. I believe that my fit process is definitely not perfect at all and should progress a quite a bit. I worry that if I buy a 54, I will end up wishing I bought a 56.

I spoke to another fitter about scheduling something soon. He said that since I am 180cm, I’m probably on the border of 54/56, but he seemed pretty confident that a 56 would be in my best interest because of a hip tear (with the included lower back pain). He suggested that although a 54 may allow a more aggressive position, a 56 will be more comfortable for longer formats? So, I guess that’s next on my to-do list.

I live in Thailand and the weather is unbearably hot, humid, and rainy so my goal is to do mainly Oly/HIM races and primarily train indoors with the occasional outdoor cycling tracks (open roads are extremely dangerous here…lol)

I appreciate all your advice! Thanks

a few things that pop out:

1. yes, 415mm would be off the charts to the left, ie. not enough reach to hit the minimum reach for the 54cm. One thing to mention is that you could use the EX-10 mono-riser from the P3x on the P5d and add a little reach flexibility that way. That said, I don’t really think you need that little reach, even though I’ve never seen a picture of you on the bike. With proper postural coaching you can hit the minimum reach for the 54cm or even the 56cm.

2. I’m immediately triggered when I hear your fitter saying that the 54cm “may allow a more aggressive position”, for two reasons. First, your position is your position, and it will be the same on either bike, assuming it’s achievable on both bikes. Second, “aggressive” is a buzzword red flag for me, ie. there’s no such thing. Positions are either orthodox or they’re not, they’re either optimized or they’re not. Aggressive and/or conservative are nonsensical words that make no sense here.

3. I’m also triggered by the logic leap from “conservative” to “being better for long course”. There’s very good reasons for getting longer and lower, and one of them is that if done right, you actually make yourself more comfortable and more efficient for longer rides. Part of it is getting weight onto the front end and off of your pelvis, but there are other factors as well. At any rate, “more comfortable for long course” is code for “I don’t understand long course bike fitting” so be careful.

Finally, seeing as how you are in Thailand, I’m confident that if you purchased a 56cm P5d and we did a remote fit together, I could get you in the right place. Or another competent remote fitter. It’s all about saddle choice and coaching about how to sit on it and then postural coaching for the rest.

Finally finally, I’d be curious to see how different crank lengths affect your repaired hip, and have a hunch that shorter cranks and thus smaller range of motion might be better for you. Something to think about.

Eric

Ok. I sent you a PM to further discuss this. Thanks!

[horaciol]

Dear Eric

I own a Felt IA 4, in 51 size, and I´m looking for a better fit. I have the oportunity of buying Cervelo, I love the new P5, but price and also availability in my country is making move toward the P-series, basically, a P-series frameset and later customize it. My fit cordinates actually are:

Pad Stack: 596mm
Pad Reach: 428mm
Pad width (center to center of pad): 228mm

I was wondering if a size 48 would be better for me, I´m 169cm tall.

Thanks in advance!

Horacio

[ericMPro]

Dear Eric

I own a Felt IA 4, in 51 size, and I´m looking for a better fit. I have the oportunity of buying Cervelo, I love the new P5, but price and also availability in my country is making move toward the P-series, basically, a P-series frameset and later customize it. My fit cordinates actually are:

Pad Stack: 596mm
Pad Reach: 428mm
Pad width (center to center of pad): 228mm

I was wondering if a size 48 would be better for me, I´m 169cm tall.

Thanks in advance!

Horacio

Hi Horacio, thanks for reaching out.

You could fit on a 48cm, but I think I’d put you on a 51cm P5d or P-Series with those fit coordinates. On a 48cm you’d be in the upper right quadrant of the fit adjustability range, whereas on the 51cm you’d be center left, with room to go lower or longer if need be. You wouldn’t have that reach flexibility with the 48cm.

Make sense?

Eric

[horaciol]

Dear Eric

Thanks for your quick reply, I perfectly understand what you explain. I would like to go lower, that´s why I was thinking of getting a 48. I attach a photo of my current setup, aerobar has no risers, it´s at it´s minumum, so you can better understand, cranks are 165mm

Best regards

Horacio

[ericMPro]

Dear Eric

Thanks for your quick reply, I perfectly understand what you explain. I would like to go lower, that´s why I was thinking of getting a 48. I attach a photo of my current setup, aerobar has no risers, it´s at it´s minumum, so you can better understand, cranks are 165mm

Best regards

Horacio

You’ve got a very workable position that really doesn’t need much in terms of stack height changes but more in “postural” changes. IE, if you properly turtled your head and shrugged your shoulders your current stack height is fine. You’d need more reach to accomplish this comfortably, and probably a little bit of tilt. You could even come “up” some in terms of pad stack in order to effectively lower your head which I know can be a bit counter intuitive.

After seeing this pic, I’m comfortable saying that you’ll be fine on a 51cm. Heck, with adding 15mm additional reach to your current numbers, which I think you absolutely need, you could hit a 54cm P5d with the flexibility to go 20mm lower, which I don’t necessarily think you need. The 51cm P5d should be perfect for you.

Eric

[horaciol]

Dear Eric

Thank you very much for your advice, I´ve changed those extensions later and put on Zipp vuka ones with 70mm height, because I wanted a more relaxed wrist possition. Regarding reach, the original retul fit posture is more backwards, like 10-15mm, but when I race or do some power intervals I tend to go forward, I dont know why, it´s feels natural to me to grab strong the extensions and move forward.

I´ve 3d printed some spacers to tilt a bit the extensions, as the Felt bar does not allow this by default. Here is a more current pic, I´ll raise the pads a little to try out what you´ve told me.

Best Regards

Horacio

[sygurvinski]

Hello Eric,

I’m looking for a Cervélo P-Series, but I don’t know if my frame size is a 51 or a 54.
I’ve got 178 cm and 81 cm inseam.

Thanks

[sygurvinski]

The Bike Fit in my Argon 18 E-117 Tri+
.

[ericMPro]

hi, thanks for reaching out.

I’m looking for a Cervélo P-Series, but I don’t know if my frame size is a 51 or a 54.
I’ve got 178 cm and 81 cm inseam.

With a Pad Stack of 628mm and a Pad Reach of 415mm you’re in the very upper left quadrant of a 51cm P5d, and similar on a P-Series, but you’re a bit unorthodox, sort of upright and I’d be concerned that once you grew into your fit you’d be needing a 54cm. I haven’t seen a picture of your fit obviously, but I’m guessing with more saddle and posture coaching you might move toward the center quadrant of the 51cm.

The great thing about a P-Series is that you can put on a shorter stem and the cockpit is very adjustable to begin with. I’d go with a 51cm using extension and pad risers to get you to 628mm and not stem spacers. If you’re thinking your position is one that will evolve and that you’ll grow into, we can talk about what it would take to do a 54cm bike.

Make sense?
Eric

[niziu]

Hello Eric
I would also like to ask you about bike sizing.
I’m about 5’9" tall. I’d like to buy new P5D. Right now I’m riding custom bike frame in size 50 (as it’s written on the frame) with long stem, with great angle and a lot of spacers over the base bar.
I’ve made a bikefitting with the results of:
Pad X: 660
Pad Y: 432
with a note that the reach should be a little be longer (I’ve had old, shorter stem).

I was trying to be more aero and in this year I experimented with my position. I feel that’s a little bit faster, but I’m struggling with my lower back pain on the longer rides with 70.3 effort (and harder).
I measured current setup, you can see it on the photo, and the numbers are:
Pad X: 670
Pad Y: 460

To be honest I thought that it would be a choice between 51 and 54 size. I’ve ridden a while on a P-Series in 56 size and it felt just too big. When I’m typing the current stack and reach it says 56, but typing the bike fitting coordinates it’s 54.
What do you think?
In the future I’d like to go a little bit lower, so I don’t think that I would need more stack margin. But all of it depends if my lower back will cope with it.

Regards, Adam