Hi Damon

I have an S5 size 54 now and have placed an order for P5 (tentatively size 51). I want to confirm the correct size for me as it seems, from the P5 geometry chart that I should order one size smaller (a 48) frame than my usual rides - granted, I am gunning for a High-V bar. I hope you understand my concern as my S5 is a size 54 and the P5 charts propose a size 48.

I currently own a Storck Aero2is (size 51 with Top Tube length 515) and Trek Speed Concept (Size M with Top Tube length 518) with
1. Pad Reach of 455 for both bikes and
2. Pad Stack of 580 (for Aero2) and 600 (for Trek SC)
3. Both are on steep seat angle settings circa 78-80 degrees - the Trek being more "laid back". I intend to set up the P5 in the forward 79 degrees seat tube angle
4. Saddle Height 72.5cm

Issue is that I would really like to have a High-V bar (I adore the Star Trek Bridge shape!) but the geometry chart shows that the lowest pad stack for a High-V bar on a size 51 frame is 611mm, which is too high for me.

If I go for a size 48 High-V bar then both pad reach and stack are in the correct ball park intersection. However, the effective top tube length on the 79 degrees seat angle setting is now 476mm, way shorter than my current bikes of 515mm to 518mm (although I believe both the Storck and Trek geometries are based on "normal" tape measurements irregardless of seat angle setting).

Two questions if I choose the size 48 based on my current pad reach and stack:-
1. Will my knees hit the High-V bar? Logically, based on the same pad reach I shouldn't but I need to confirm.
2. Are you able to share the stack and reach of the pursuit bar ends themselves (same as arm pad stack/ reach definition but to center of the pursuit bars)? I think there are people with preferences for short/long pursuit bar reach and/or low/flat pursuit bar stack. These figures are good to know as well.

Thanks for your help.

Hi Damon,

Maybe I misted it,....but did you mention something about compatibility of the P5 UCI legal AND Triathlon version frame sets with other than the new Magura Hydrolic Brakes ? Es specially about the rear brake (caliper type?) because of limited space.
Hope you can shine a light on this, thanks !

Eric

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EJ is a Physician assistant, Cervelo Bike Professor, Dreamer, Triathlete, ex-Photo amature...Earthling

Hi Discover,

You're right in understanding the High-V will drive you toward a smaller frame. Don't compare to your road bike frame size; it's common for road and tri bikes to be quite different sizes, even for the same rider. Just go by Arm Pad Stack & Reach.

You also understand the P5's APS&R table perfectly, and your choices in 48 and 51cm frames.

To answer your questions:

1. Knee clearance: With the same or similar saddle set back and APR, your knees won't be any closer to the arm pads than on your current bike. (Your logic is right: pay no attention to top tube lengths, refer to APR instead.)

2. Aduro base bar stack & reach: Since the bar goes up and down the steerer tube with the addition or removal of fork spacers, I'll give you numbers from the base of the stem:
Stack= 21mm
Reach=230mm

Add and subtract these to frame stack & reach, then adjust them based on fork spacers to get the total base bar stack & reach from the frame's BB.

Rule of thumb: For typical head tube angles, the change in reach is about one third the change in stack. For example, if you add 30mm of fork spacers, stack goes up by about 30mm and reach decreases by about 10mm.

FYI the 48cm P5 uses 650C wheels, if that's important to you.

Cheers,

---

Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Hi EJ2,

Brakes are standard center bolt mounted.

The P5 frame accepts the Magura hydraulic rear brake or Campagnolo or TRP aero brakes. The UCi legal frameset comes with the TRP rear brake.

There are two P5 forks:
P5-Three. This fork has 3:1 aspect ratio blades and is UCI legal.
P5-Six. This fork has 6:1 aspect ratio blades and is not UCI legal.

Both forks accept the Magura hydraulic front brake or any normal brake (side or center pull). The UCI legal frameset does not come with a front brake. The matching brake covers only attach to the Magura brake, so if you use a different front brake you won't be able to use the brake covers; but the normal brake still fits on the fork.

Cheers,

---

Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Thx Damon,

So to be sure, not compatible with SRAM Red like brakes ?

Thx again,

Eric

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EJ is a Physician assistant, Cervelo Bike Professor, Dreamer, Triathlete, ex-Photo amature...Earthling

Hello,

Thanks for being so diligent in your responses to everyone.

I'm not 100% on sizing, but will be fit this week and get "my numbers" and will then attempt to apply them to your published chart. If that turns out to be over my head, can you estimate when there may be an LBS somewhere with any inventory to the extent that I could hop on and actually fit with a real bike under me?

I live in Florida, but travel to NC on business quite a bit and was told by an LBS there that they are the "3rd largest Cervelo dealer in the country". When, for example, might a shop like that be holding some P5's in a variety of sizes in order to "actually fit" vs. "virtually fit" (aka, for me, "guessing").

Finally, when might framesets only be available?

Thanks in advance,

---

"What do you mean your running shoes don't match your bike?"

Hi OCD,

Thanks for considering a Cervelo.

Production has begun, and the first batch is nearing completion. We expect to start shipping the first P5s in late March. However, quantities will be limited as production will ramp up slowly at first. The Aduro bar is expected to be in especially short supply, so (wild guess here) the P5 frameset without that bar may have easier availability initially. Check with your Cervelo retailer for the best detailed information.

Cheers,

---

Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Hi EJ2,

SRAM Red brakes will attach to the fork and frame (common center bolt mounting style). The front works with no problems. But like most other frames with brakes near the BB, the rear brake may hit the crank arm depending on the details of your crank and brake. We didn't even bother checking for compatibility, since no P5 will be sold without either a Magura hydraulic brake system or a TRP rear brake supplied.

Cheers,

---

Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Hi Damon

Thank you for your patient and detailed answers.

How could I have missed 650C wheels for the size 48? My choice is therefore simpler - stick to my pre-order and settle for the size 51 (High-V bar, arm pads slammed back in order to replicate my current Speed Concept setting).

You mentioned about stack adjustment using fork spacers. My questions follow:-
1. Is your APS column in the APS&R table based on zero fork spacers?
2. I note a text box labelled "Fork Spacers" next to the APS numbers in the range of 566mm to 626mm. I presume you mean fork spacers can be added to raise APS throughout the entire range. If so, is there a standard spacer height for each spacer and are they standard cylindrical or aero/ frame fitted shaped spacers?
3. If fork spacers are to be added, then presumably the stack height of the front brake cowling will have to be increased accordingly or an aero insert be added to fill that space between the stem and top of head tube?

On the Aduro bars-
1. Can you clarify the point of reference for your bar reach measurement of 230mm? Is it from the center of the steering tube hole (which I understand is covered up) to the tip/ center of the base bar ends or back of stem to tip/ center of bar ends?
2. Are there plans for shorter stem lengths (circa 60-70mm)? I ask this as I prefer the sharper handling of shorter reach base bar ends and my APR can still be within my current adjustable range.
3. The closed top cover of the stem means that I need to be absolutely certain of how many fork spacers to insert (if any) to achieve a desired APS and base bar stack height before I cut the fork steering tube. This means that any experimentation with fork spacers and resultant stack heights must be done before I cut the steering tube. My questions are how can I experiment with this and whether there is some "free headroom" within the space of the Aduro stem to fine tune this height, after cutting off the steerer tube?

As a suggestion and feedback to 3T, I think that there should be a steerer tube hole on top of the Aduro stem so that flexibility is maintained and pre-owned value can be maintained. The picture below of the Zeitjaeger bars on my Storck Aero2 shows what I am talking about.

the handle bars look tricky to me.

Hi Discover,

Good questions. Thanks for your clear list. I'll answer each one in order.

1. APS includes effects of both Macro components (High-V or Low, etc.) and "micro" components (fork spacers).
2. Within the table's boxed range for a given frame size and Macro height setting (e.g., 51cm frame, High-V bar), the different APSs listed are achieved with fork spacers. The bottom row assumes no spacers, and each row above that is achieved by adding 5mm of fork spacers. Aduro spacers are included: Four or five (can't remember right now) 10mm spacers and two 5mm spacers. The Aduro spacers are a perfect aero match with the Aduro stem and P5 frame, and extend forward and rearward to complete the TrueAero(TM) profile.
3. The aero match between stem and spacers means the front cowling attaches either to the underside of the stem (if no spacers are used) or to the underside of the bottom spacer (if spacers are used). At Cervelo, we call it the "beard" since it "grows" downward from the stem's (or spacer's) "chin."

For the Aduro bars,

1. BBS&R are measured from the center of the steerer tube hole, at the bottom. Essentially this is the same point as the frame stack/reach point. Just like a typical stem, this point moves up and back as fork spacers are added. The center/tip of the base bar is the far end of the measurement.
2. For now there are no plans for different stem lengths. The basic stem is about 90mm, and arm pads adjust forward 25mm or rearward 25mm to produce effective stem lengths of 115 or 65mm for the arms. But not, as you know, for the base bar.
3. One of the design goals of the Aduro was 100% internal cables, which reduces aero drag. To achieve this the cables go over the top of the steerer inside the stem. One of the nuances of this design is that even if there were a hole in the stem, the cables would require the fork to be cut, since they cannot go around it. Adding headroom would have added aero drag (frontal area) and weight (more carbon) so please be sure before you cut. Thanks to the standard 1 1/8" steerer diameter, you can experiment using an adjustable stem or other standard stem before cutting. If you decide to raise your arm pads later, you can always add spacers under each arm pad's base plate. The bolts are 25mm apart so several common arm pad spacer kits will work.

Cheers,

---

Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Yes, the main problem with the Zeitjeager bar is that the extensions are attached to the base bar whereas the pads rise above the base bar (unless you ride with zero arm pad risers). This gives you a "nose-dive" position for your forearms which makes it uncomfortable. Ideally the extension bars should come out from right under the pads. I have since changed the s-bends to ski-bends and this allows my forearms to be horizontal. Much better now. What I like about the Aero2 bar though is the shorter reach of the pursuit bar ends - I think this is personal but it does give me better handling around corners.

The Aduro bars are similar to my Speed Concept bontrager aerobars in terms of a forward V shape (which actually results in a longer bar end reach) but more importantly, the arm pads are together/ just above the extension bars.

Hi Damon

Thank you for your crystal clear answers. You have now decrypted the entire APS&R table (and more) for me. Cervelo is certainly lucky to have you working for them (not just in your patient answers but attention to design details)!

Profiled fork spacers is an elegant and essential touch to details. You should copyright the "bearding" analogy - excellent.

If I step back to digest our exchange so far - P5's APS can be adjusted firstly on a macro-level by the choice of High-V/ Low base bar (which affects more of APS rather than base bar stack) and then on a finer level by two micro components - aero profile fork spacers (which affect both base bar stack and APS) and arm pad spacers (which affect APS). I think this should address most of my concerns. As for experimenting with fork spacers, then yes, I guess there is no other way apart from trying with a standard test stem and bar - the things we need to do for 100% internal cabling!

One other "design" proposal more for Di2 users - is it possible to provide an opening at the top of the stem cover to embed/house the Di2 control unit so that the cables are fully hidden but control face flush and visible from the top of the stem? From the internet photos, I see the Di2 control unit cables exiting from the rear of the stem and the unit itself attached to the side of the stem. Maybe have this as an optional (better still, make it standard option) stem cover for Di2 control unit? Hate to see that with hidden batteries, hidden steerer top etc etc, this tiny bit of cable (and a chunk of protruding control box) would make the design only 99.9% internally cabled. I mean this as no disrespect for the excellent design work for the P5 but something that I hope you can include to make it even more perfect.

Cheers

Hi Discover,

You got it! All's clear.

Regarding the Di2 junction box location: We debated quite a bit among ourselves about where to put it, and we did consider internal placement. Due to many reasons, including cables occupying that space and accessibility, we decided to mount it externally.

The two places we anticipated people might want to mount it are on the side as shown in the photos, on on the top, in the base of the V. For these builds we chose the side, since the box is then somewhat hidden aerodynamically in the wake of the base bar, and also because the side of the stem is flat and a good fit with double stick tape on the flat back of the junction box.

On the other hand, mounting the junction box on the top would make it more visible, if you like to look at the lights more frequently, but it also puts the box in relatively cleaner airflow. Also the contoured surface could be difficult to stick the box to.

In the end, the athlete has the choice where to put it. I wouldn't be surprised if in the future Shimano updated the shape to one designed to be recessed.

Thanks for your questions, I'm sure others also benefitted.

Cheers,

---

Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Hi Damon

Thanks again for sharing your thoughts on the Di2 junction box. The primary purpose of forums is to share knowledge and experience - you have provided much more than that with insights on your thought process behind the micro-design features of the P5. I can see a lot of thought and effort have been put into the design to make it "simply faster". This gives consumers like me more confidence in putting down hard-earned money for the P5.

Can't wait for your white paper. If you ever need an average Joe rider to test your new models or give consumer feedback on upcoming features, please remember me *wink*.

On the Di2 junction box again, I was actually thinking of something like housing the box flush with the stem as in the photo below. Probably below the stem to provide better resistance and "residual drainage" post wet weather conditions.



If this is not likely, then will I be able to tuck the entire box inside the stem? If I really need access to the box (which is rarely based on my experience so far), then I can merely unscrew the stem cover.

Currently I am able to tuck the junction box into the rubber aero hood behind my Speed Concept's stem and hate to see anything "inorganic" to the bike's profile sticking out anywhere.

Cheers.

On the subject of Di2 and drag penalty, I know you've mentioned the drag saving from hiding the Di2 battery, but was wondering if you've done a back to back test of a Di2 vs mechanical bike to say how much drag the bulkier Di2 mechs add, if any?

Hi Steve, I've wondered that myself, but so far we haven't prioritized tunnel time to compare the drag differences of mechs themselves.

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

I am planning to build a P5 with Di2.There are a multitude of kits:7972,7972-B,7973,7973-2,7975,7975-A1,7975-A2.Which of these kits are for the P5??Thanks

Hi Damon,

Colours have been nailed to the mast! P5 (tri) ordered. Size 51 so I'm expecting to wait just a little longer. I'm in the uk - so what's a reasonable estimate for delivery?

Could you also please confirm for me what I can expect to find in the box when it arrives.......if I've missed this sorry.

Also - I see from the internet images....lots of testers (pro's?) etc running around in those lovely "Simply faster" t-shirts. Don't you think it would be an absolutely fabulous idea to put one in the box for every new frame purchaser! think of the advertising!.......Mines a medium please ;-)

Brian

Hi carbonsport,

We use the Tri harness. It's longer than the road wiring kits, which makes wiring the handlebar easier and allows lots of adjusting range for the extensions. I'll try to confirm which Shimano part number that is.

Cheers,

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Hi Hoolywud,

Nice to hear! Thanks for paying my salary. ;-) I don't have visibility into delivery schedules, so your Cervelo retailer is the best source for information about delivery schedules.

The P5 arrives with all the stuff listed on the web site: www.cervelo.com, Bikes, P5, Prices & Specs.

Unfortunately the "P5 Simply Faster" T-shirts were only made for the P5 launch; I'm keeping my L as a souvenir!

Cheers,

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

That is some impressive di2 integration. What bike is this?

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Advanced Aero TopTube Storage for Road, Gravel, & Tri...ZeroSlip & Direct-mount, made in the USA.
DarkSpeedWorks.com.....Reviews.....Insta.....Facebook
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http://www.englishcycles.com/...ustom-di2-road-bike/

The cranks in the end did not work out for the owner so he switched them out.

What can I say?

Wow.

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Advanced Aero TopTube Storage for Road, Gravel, & Tri...ZeroSlip & Direct-mount, made in the USA.
DarkSpeedWorks.com.....Reviews.....Insta.....Facebook
--

Yeah. Mr. English does nice work. How about those "Sweetwings" cranks on that thing? I have a friend who actually still rides a pair of those on his everyday bike...

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http://bikeblather.blogspot.com/