hey Dimm, thanks for reaching out.

I have some thoughts about your fit and fit process, but first let me address your comments from the other post:

Regarding the P5d basebar width and pad width and tilt, I definitely recommend getting the EX10 mono-riser. I know it's an additional administrative and logistical item to solve, but your LBS should be able to sort it out for you. In addition to additional pad width flexibility, the EX10 will give you additional reach flexibility as well as the all-important native tilt function. As for basebar width, you are a triathlete, and should be in the aerobars at all or nearly all times. 38cm is narrow only if you compare to 44cm, but it's quite wide compared to 22mm or 15mm, etc. IOW, it is what it is and in no way will affect comfort or handling. FWIW, I'm 6'2" and on my various bikes have 44cm road bars, 40cm road bars on my aero road bike, and I assume 38cm TT basebar on my P5. I guess what I'm saying is use the right tool for the job. Pack sprint in a road race? 44cm. Time trial or triathlon where you're barely on the hoods? 38cm. As for height, I think that will be fine too, riding the hoods on a P5d would be similar to riding in the drops on your road bike.

Now the fit. I'm immediately drawn to your fitter's use of the word "conservative", which alludes to an opposite or connected word "aggressive" and as you might know neither of those words are in my vocabulary as a fitter and indicate a lack of understanding of a good time trial or triathlon position. There is only "optimal", and everything else is sub-optimal. OTOH, your fitter did say "rotate", which is the correct mental model or framework to understand what's happening when you go from a "slack" position as your fit coordinates indicate to a more orthodox one. Your coordinates of Pad Stack of 690mm and Pad Reach of 451mm are in the upper left quadrant of a size 58cm P5d. This would indicate to me, lacking a picture of your fit of course and assuming that you are the same kind of different as everyone else, that you have some room to grow so to speak with your position, or that your position could evolve to a longer and lower state. Either way, the 58cm P5d will accommodate this, *especially* with the tilt function of the EX10 mono-riser. No matter the riser height, your stiffness and handling will be fine. Stiffness not really an issue, and you're effectively shortening the stem as you come up so handling will be fine too. There's no configuration of the P5d where handling becomes an issue IMO. The stem length is fixed IOW.

Finally, the bike will certainly not be ill-fitting. You're squarely in the range of the 58cm P5d and it would be perfect for you IMO, especially with the tilt function of the EX10 mono-riser.

Make sense? LMK if you have any questions and let's keep the conversation going.

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Thanks, Eric. This is really helpful, much appreciated. Some small clarifications, if I may. I wonder how many cm the P5D riser will have to go up in my case (assuming padstack 690, just interested in the optics of it)? What is the maximum center to center pad width of the original cockpit (Cervelo only provides 286mm edge to edge)?

I have also been looking at the PX-series, although I am not a fan of the look and I don't currently plan on doing anything longer than HIMs. Is there any reason/advantages from the fit perspective for me to look at the PX vs the P5D?

Thank you

Dimm

With the 58cm P5d, you'd have 79mm of mono-riser exposed with the native kit and perhaps a little less with the EX10. On the P3x or PX, you'd have 97mm of exposed mono-riser on the size L and only 69mm on the size XL.

Depending on your hydration strategy, and depending on how COVID affects races and aid stations going forward, a P3x or PX series bike might make a lot of sense. You could easily carry 3-4 bottles aerodynamically with the PX, which would get you through even the hottest HIM bike course.

I don't see a difference on fit or handling. The XL PX bike has only 2mm more front/center, which adds the same 2mm to the overall wheelbase. That extra 2mm of front/center and the native tilt kit and the aerodynamic hydration and storage in these weird times might be enough to tip the scales for you though.

Let me get back to you on pad width. I like to measure not outside to outside like Cervelo does nor center to center like you and a lot of others but "curve to curve", ie. the point on the outer pad where it starts to curve upward. This is where your elbows are going to settle and push outward, and thus the pads are there to push back inward. The width options are greater on the P3x or PX or EX10 mono-riser.

Eric

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Much thanks, Eric. I am leaning towards the P5D in 58. Depending on the max pad width, I will decide whether I need to order the EX-10 riser right away ot try the the native cockpit first.

Thanks Eric!

That definately makes sense. I've set up an appointment with my LBS to take a look at the extension/junction box thing next week, but before I turn over the bike to them I'll go home and try some more pad/position combinations. Another thing I just thought about (doh); my saddle is currently in the middle seat post position, and moving it to the forwardmost position will help move me further forward in the extensions...but will that create a seat angle and seat-to-BB distance that is too steep/short?

Regards,
Soren

OK, keep me posted. There are other ways to get the all important tilt outside of the new mono-riser. Aftermarket wedges with the ski bend extensions that come with the P5d work as well.

Eric

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I think as long as you are engaging your glutes (thus rolling your hips forward, a function of saddle comfort), and not hurting your knees or burning out your quads, you can set your saddle steepness how you like.

But yes, move the pads forward was my first thought ;)

Eric

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Hi Eric,

Just checking if you managed to find the max pad width of the native cockpit (c-t-c or your preferred metric)?

Much thanks,
Dimm

Hi Eric,


I am in need of some bike size advice. None of my local fitters are taking appointments, yet. I bought a Cervelo S3 online without testing one first. The store recommended a 51 cm in the aero road bike, but then shipped a 48 cm in error.
Before I send it back, I'm seeking alternative opinions on size. I currently ride a 48 cm P2. I'm 61.75 inches tall with a 30 inch inseam. The salesman in my LBS said he would have recommended the 48 if he had one.


I have only been properly fit to the P2 (with 650 wheels). Here's the data for the P2 if it is helpful in providing advice on the correct size of an S3 road bike. And here's a link to a video showing the results of the P2 fit: https://www.youtube.com/watch?v=vsSHNZiqDrc

Stem: 10 degree, 80 mm
Spacer Stack: 35 mm
Crank: 165 mm

Frame Stack: 459 mm
Handlebar Stack: 556 mm

Frame Reach (BB to center of headtube top) 391 mm
Handlebar Reach (BB to center of bar) 431 mm

Handlebar Reach (tip of saddle to bar top) 442 mm
Arm pad reach (tip of saddle to back of arm pad) 383 mm
Arm pad reach (BB to back of pad) 372 mm
Grip reach (tip of saddle to front end of grip) 658 mm
BB to Grip Reach: 648 mm
Handlebar Stack:

Saddle Height (BB to center of saddle) 658
Saddle Setback: -10 mm

Arm Pad Stack BB: 591 mm
Saddle Angle: 0
Eff. Seat Tube Angle 78
Grip Angle 47

hi Dimm,

the pads go from 226mm to 286mm O-O. A max of 286mm outer edge to outer edge computes to a max effective width of about 250mm "curve to curve", the point at which the pads sweep/curve upward and where your elbows should contact the pads.

Eric

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hey there, thanks for reaching out. The P2 information was very useful.

First of all, ***red flag***: "the salesman at your LBS would have recommended the 48cm Cervelo S3 *if he had one*". This is not good for you, nor is it good business or good for him in the long run. I'd be wary of any information from this particular shop from here on out.

That said, let's figure out your optimal size:

First of all, with 35cm of spacers and a +10 degree stem on your 48cm P2 Classic, I'm automatically putting you on a 51cm P2 Classic. So there's that.

Next, your fit video confirms that you'd definitely need that extra reach of the 51cm based on your pelvic tilt and back arch. So, I'm comfortable saying you're a 51cm for a TT bike.

So, converting to road. There's a couple rules of thumb, or a few. One of them is plain wrong, the one that says get a TT bike one size *smaller* than your road bike size. The other two (same same, or size up for TT) are reasonable. The major difference between the 48cm S3 and the 41cm S3 is really a large difference in head tube stack (25mm) and standover height (29mm). The 51cm is only 9mm longer in reach, easily normalized with a 10mm longer stem. The front/center is only 2mm longer on the 51cm, and the wheelbase is only 2mm longer as well. It's almost the same bike, but the 48cm is much more suited for shorter riders. Is that you? I'm not sure... I'd hate to see you on a 48cm bike with 25mm or more of stem spacers when you could have been on a 51cm S3 with no or fewer stem spacers and a 10mm shorter stem.

If you've got *any* standover height flexibility, I'd go with the 51cm S3.

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Thanks Eric for the detailed explanation and recommendations for the sizing of the Cervelo S3. Inseam should be long enough to accommodate the stand over height of the 51cm. I'll pack up the 48 and hope they still have the 51 that I originally ordered. With no triathlons in the near future, I couldn't pass up the sweet deal on a road bike.

Cassie

Thanks, Eric. I am not sure how the curve to curve measurement will practically work for me compared to what I tried in my pre-fit session (I suspect it is a bit wider measurement than center to center as it doesn’t take into account the width of the elbows), but in any case around 250mm doesn’t sound very narrow to start with.

Dimm

If you need center to center I use 90mm as the width of each pad

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Thanks, Eric.

Eric,

Hi. 71". Pad stack 640 mm, Pad reach 460 mm, Pad width (center-to-center) 240 mm. Seat height 760 mm. Nose of saddle close to directly over BB.

Miss my old P3C from the 2010 era. Upgraded to a BMC TM01 M-S a while back then stopped racing due to back issues. Since undergoing a lumbar fusion, I'm able to resume the TT position pain free. Looking at either a P5D or P3X for 2021.

Thanks, Brian

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"We don't inherit the Earth from our ancestors, we borrow it from our children." --Chief Seattle

Hi Eric,

I'm interested in a PX or P5D

My coordinates are

Pad X 475
Pad Y 605
Width 190
Saddle Height 760
Tilt 10 degrees (could do with spacers on P5D? or??)


This fit is a progression on a 6 year old fit from my current P5 (size 56). Aim is to work on flexibility to narrow the width, drop the Y a little more, and possibly move the X forward a little bit more.

What size do I need, prioritizing handling and aesthetics? e.g. not a ton of rise on the bar unless it would really make that frame the better bike to ride.

hey there, thanks for reaching out. FWIW, every client I've ever had who got the M-S BMC wished they were on an M-L.

Anyway, with a Pad Stack of 640mm and a Pad Reach of 460mm, you are between a 54cm and 56cm P5d, with a heavy lean towards the 56cm. You'd be upper right quadrant of the 54cm, center to upper left of the 56cm. IOW you'd only be able to get 10mm longer on the 54cm and that's not much. 56cm would be much more versatile.

For the P3x, your fit coordinates come out between a size L or XL, but with a heavy heavy lean to the size L. In this case the size L would have 20mm of additional reach while the XL would only be able to get 20mm lower. So, it's easy to say size L but it's a more subjective call... if you knew for sure your position is dialed or you'd never ever get longer but maybe lower (which is the opposite of my experience and sort of counterproductive to go lower without also going longer), you could go with the size L. A branch to that one would be that if you knew that going 20mm longer would thus dial you in, you could again go with the size L. However, if you knew you'd never get lower but might get significantly longer in the future you do the size XL. I'd have to see pics to be sure.

Get the bike that's long enough that also allows you to get low enough, and get the bike that's low enough but also allows you to get long enough.

Make sense?

Eric

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Hey, thanks for reaching out.

You have a sort of "low" fit coordinate profile, and are perfectly placed on a size L P3x, in the center low quadrant. You could in the future only get 10mm lower but significantly longer. A size M would also fit, but with more exposed mono-riser, and the ability to only get 15mm longer.

Like the poster above/before you, it's a matter of where you think your future position, if any, will be and what you want your bike to look like. My gut says that at 605mm you're low already so going longer might be an option in the future but not much lower so a size L would work, but could only go 12mm lower. OTOH, if you absolutely knew your reach was already maxed out, there's some data out there that says a high mono-riser is faster than a low mono-riser all other things being equal. Aesthetically, I don't think you can go wrong with a P3x no matter where the mono-riser is, based on the design. It's not like having gaudy spacers under a positive 6 or 12 stem. Also, it's only 40mm of extension on the size M.

For the P5d, you have a similar situation between a 54cm and 56cm P5d, but in this case I can definitely recommend the bigger bike, as on the 54cm you'd be maxed out on reach but on the 56cm you'd have reach *and* lower stack (only 12mm) options in future, if necessary.

If you're at the end of a 6 year fit progression and want to get *a little* lower and get longer I'd go with the 56cm for sure. Longer is always better IMO. Handling and aesthetics would be the same for both bikes honestly, although if you're maxed out on reach or getting longer the longer bike will be better.

Make sense?

Eric

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Eric,

Thanks a ton. Playing with a few things and will get a second Retul fit for triathlon (have had triathlon fit many years ago and a road bike fit last summer) very soon to include optimization of crank length. Lots of changes I'm guessing so will slam the length out on the BMC until the Spring. What you're doing for us on here is amazing!!!

--Brian

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"We don't inherit the Earth from our ancestors, we borrow it from our children." --Chief Seattle

Eric,

Thank you sooooo much for your detailed answer. I really feel a lot more confident about putting down my money for the right size bike! Thank you!

Hi Erik,
my wife and I purchased two beautiful Cervelo: PX (me) and P3X (my wife).
We managed to make a spectacular bike fitting; the only flaw is that the basebar in the low position is too low and in the high position it is too high; if there was the possibility of mounting a flat basebar it would be perfect; is a similar version of basebar available on the market?
Another question: when cycling on steep slopes, the hands tend to slide forward and there is no possibility to rotate the basebar upwards for safer support of the hands; Is there any modification we can make to brake our hands and travel downhill safer?
Thanks a lot in advance for your support
Ricky

Hi Eric,

I’ve attached my last Tri bike fit. Apologies as the measurements are different to the ones you specify.
Sadly don’t have this anymore so can’t input the x and y coordinates you refer to. Had a look at my road bike but not all that helpful.

It was a 54 P2, I’m 176.5cm and longer torso and shorter legs. Bars were 3T aura pro. I have long arms. Saddle height is 77cm from BB. Looking at pics of me on this I do wonder if it was a bit small as knees and elbows were a bit close.

Interested in a new p series, p3x or p5d, whichever fits best. Mainly olympic distance and 70.3s and potentially IM eventually. Can DM you other fit images with me on it if helpful?
Many thanks.

hey Ricky, thanks for reaching out. I'm Eric with a C, not a K! Those K people are evil ;)

Not sure about the basebar for the P3x/PX. I'll have to check on that. Same for the hand grips on steep descents. I'd have to ask some of the bike shop types or athletes that have been riding the PX type bikes for a long time and have more experience than me. It looks like the hand grip is raised at a certain spot to help with grip.

What about the basebar being "too high" is too high? I've heard anecdotal evidence that turned up is slightly faster. Would knowing that help with your feeling about how it looks? How often are you riding on the hoods anyway?

Eric

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OK, let me work on this... do you have a picture of you on the bike?

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