well, again, there's the difference between "well designed" as expressed in road race products versus what we see in triathlon.

i'm ambivalent about wider tires. i like them, theoretically, if you realize that i've come from 19mm and 20mm tires (in the 80s) to 23mm, to 25mm and now contemplating 28mm tires. i don't know what will be faster aerodynamically, in the end. i suspect it might have to do with rim shape and depth (maybe a 28mm tire is an aero dog on a 30mm rim, compared to a 23mm tire on a 30mm rim, but it might be great on a 70mm rim). i don't know how frame manufacture will be negatively impacted by the REAR tire being that big.

i don't know whether disc brakes will make bigger (wider and taller) tires easier to slide into the rear of frames or not. and i don't know whether in the end the bigger tires will be a net gain.

i have a suspicion. but i don't know. we'll see.

---

Dan Empfield
aka Slowman

As an English major as well, and with some experience in technical writing, I agree. Nicely presented.

---

"There are two ways to slide easily through life- to believe everything and to doubt everything- both ways save us from thinking "- Korzbyski

Personally, while I feel the work to gather the data and the generated report are great, the section about "Starky" and IM Florida has no business being in the report. I see this as marketing spin I would expect from a manufacturer trying to sell a bike by taking a rider and bike that weren't part of the tests and making assumptions to show much faster that rider *could* have been on some of the bikes in this test. Did Cervelo sponsor this section?


This is equivalent of saying that since Starky rode 3 minutes faster in an Ironman on the new Ordu vs the old Ordu, and the P5-X is only 2 minutes faster than the old Ordu assuming the old Ordu matches the baseline Felt, then the new Ordu is 1 minute faster than the P5-X.

Or in other words "I see you've released the most thoroughly researched and intensively designed bike in history. Nice job. Give me a moment and I'll show how a simple upgrade to your 5 year old design can both improve the fit range and match the aero"

Disc brakes aren't all that relevant to that observation. And it I'd managed to get into a position of influence sooner (it has been a very long term project) we'd have had better bars already.

Cervelo have shown that disc brakes are slower with their design methodologies (that's not saying that they can't be equal using another approach). The differences on that graph are nearly 3 times the increment between P5 and P5X.

So we're looking at the tradeoffs made. Does the loss of the brake at the fork crown influence shaping (and the adjustability of the bars) to make up for that difference? Seems unlikely given the how well some brakes are hidden in forks. So the P5X is a really fast frame that is likely being held back a bit by discs.

Then we look to the wheels. Wider tyres are less aero, rim designs just mitigate that.
So we're relying on wider tyres having enough lower rolling resistance to compensate for all the penalties incurred along the way. Which so far is looking like a weak assumption.

The strongest argument for discs is that we can get to being roughly neutral (maybe) on aero/rolling performance but have much better braking power than most of the hidden brakes. I'm a big fan of safety so that is a meaningful topic.

I'll be designing for discs because no one is thinking like Tom - that we should make rim calipers that can go wider.

I'm not saying that though...Josh says that the "diminishing returns" aspect of going wider on tires and rims puts a "limit" on going wider (for timed racing on pavement) at ~28-30mm of measured tire width...and I'm saying that current brake technologies are perfectly capable of accommodating that width. It's the frame and fork designs that are the limiters, and are mostly that way because the designers didn't contemplate at the time riders wanting to use tires that wide on the road.

Take a look at the fork on all the new Tarmac pics out there today...they specifically state that they used a direct-mount brake design because the could then make the crown wider and more aero. The pics I've seen also show it shod with 26C Turbo Cotton tires on Roval CLX50 rims...the combination of which I'm sure has those tires measuring out at near 30mm (if not 30+)...with plenty of clearance.

In other words, the rim brake tech is already THERE to go wider than us currently in vogue...its just that the frames and forks don't always "play nice" ;-)

---

http://bikeblather.blogspot.com/

and that's a pretty strong argument. and it's a long way past what was said 2 years ago, which is that there is an un-overcomable aero penalty to discs.

but i would add one more thing. this argument about discs being aero neutral (maybe) doesn't contemplate any effort (yet) to leverage the ability to change the frame and fork design to optimize for the freedom of no rim calipers.

cue the folks who say that won't improve anything. (who are the same folks who said 2 years ago that there was no way a disc brake bike would be the aero equal of a well made rim brake bike).

every time a disc brake bike overperforms there is a new caveat. i love rim calipers, and the bikes made with them. i just don't understand why other folks' marriages are harmed by the existence of disc brake bikes that perform equally (and with better braking).

---

Dan Empfield
aka Slowman

So, this is basically what I was thinking too - I have a 2009 P2 and thought I was in the market for a new bike but now I'm not so sure. The Felt B and old Cervelo P2C really aren't that different and the performance of the Felt in this study is very, very close to the 'superbikes'. It seems to me the benefit is mostly in the front end incl an aero brake and cleaning up the cables... which is a much smaller investment than a new bike...

Just as a point of reference - The Tactical - as tested in this report can accommodate a (measured 28 mm) tire (with clearance) on the front - limited by integrated center pull brake pad clearance.

The only reason it is limited at 28 mm is because someone might what to use a 19 mm tire and there is an "effective range". If I knew tires under 21 mm were no longer an issue I could easily modify the design of the brake to accept wider tires without issue.

---

Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com

Debatable. Some of those old steel bikes with the really, really skinny steel tubes are actually pretty quick. John Cobb did some tests at TAMU - I don't believe the results are posted anywhere tho - of some old steel frames with tube diameters of - IIRC - 18mm and found that they were substantially faster than many aero-in-name-but-not-in-practice frames. Now, granted, those pseudo-aero frames would get blown away (pun intended) by these modern bikes listed in this paper (and many others), but really skinny tubes are pretty fast, especially with good deep dish wheels and a disc to clean up the airflow.

Aside from the fact that it would not be financially practical given the constraints of this test, it actually would have been pretty cool to have somebody like a Carl Strong build a super slender steel tube frame to compare to these "superbikes." I bet it would actually do okay if the wheels/bars/brakes were put on it.

And, of course, if we start talking about aero alloy (or steel) tubesets, then the conversation becomes even more interesting. Tom Anhalt found his "AeroCamino" is really pretty dang quick, thanks - at least in part - to some tricks like running the downtube in reverse orientation from what's suggested, but also thanks to brake choice and brake position.

Certainly when it comes to storage options these bikes might pay an especially large relative penalty, but I do think that if you take everything in total, I bet you could make a really fast package based around really slender steel tubes...

---

"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

This post is just loaded with mis-representations of previous statements and straw man arguments :-/

But, who am I to get in your path...rant away!!

---

http://bikeblather.blogspot.com/

Dan, do you you not think that - given the realistic need to put the limit somewhere - that you wouldn't be better off excluding customers who want 19mm tires in favor of giving an option to those who want 30mm tires?

I.e., if you have to exclude someone, my own thought would be to accommodate 21-30mm as opposed to 19-28mm. I think the former range gives you more potential customers than the latter...

---

"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Its great P5X is fastest out there. But for $18000CAN? That is like 6 P3's!

---

@rhyspencer

Yes I totally agree with you and that might be another development item. The front end of the bike was designed and tested 18 months ago. A lot of work went into getting everything just right. At the time 23-25 mm tires were what most athletes were telling us they hoped they could use. I'm just glad we can accommodate 28 mm. I just did not look far enough into the future.

One of the difficulties with design is setting a cut off date and moving toward a sellable product.

You can expect to see that brake development on the Tactical about this time next year. Right after the aero-road bike is completed and the XS Tactical goes to mold deign. Plenty of work to do:-)

---

Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com

I can't find the Cervelo white paper now but other people here on the board will back me up on this: a bottle between the arms is either drag neutral or a slight drag reduction. Cervelo did a study with their foam mannequin on this subject a long time ago.

are you assuming i'm referring to you? or only to you? or are aggregating and appropriating for yourself all the statements of all the people to whom i might refer?

---

Dan Empfield
aka Slowman

It's in the Cervelo P5 white paper

---

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

I think there are a few things that create a bit off caution over the move to discs. The most obvious is cost. A lot of racers build up a wheel collection over time. A change to discs makes these obsolete and the cycle starts again of building up a new collection while the resale value of your rim brake wheels dips.

It might also take a while for a standard Adel type to be decided. If you have some disc brake training wheels it makes sense if you can also use them in your disc road bike as well as your TT bike.

Then there is a question of need - given the costs etc are the performance gains great enough? There will always be the question of if a rim brake version of the P5x might be faster still. Or if a geared and hidden brake version of the TGB5 track bike would be a bit more aero still. Pressfit BB's come to mind as some thing were sold as a step forward but actually feel likeva step back. May be its just me but I still think the old octlink style bb's spin with less friction (without the need for cermicspeed bucks). So understandable the people question the need.

I think though it won't be long until all new bikes are disc brake bikes and if the P5x is anything to go by we wontvbe going slower because of this fact.

i have a question for you, but this requires a little background. when i started racing bikes the wheels were all sew-up, there was a male thread on the hub, and we threaded on a freewheel, which had 5 cogs. the dropouts were spaced at 126.5mm.

since that time we've moved, incrementally, over the years, from 5 cogs to 6, to 7 and from freewheels to cassettes. then to 8 gears, 9, 10 and now 11. we've moved from sew-up to clincher. the spacing has changed from 126.5mm to 130mm, to 135mm (and upcoming to 142mm with discs brakes).

you can imagine how many times i've needed to upgrade my wheels and this doesn't include the wheelsets i've owned that are 559 bead diameter, 571mm, 584mm and 622mm.

these are all standards. this doesn't touch on the use of the wheels, just the necessary standard to make the wheels work with the bikes or tires or gears or shif system or frame spacing that i'm using.

so, my question: at what point should we all have demanded that technology stop? because i hear you loud and clear. i suspect my tenure in the sport is a lot longer than yours so i've been voicing the same objection you're voicing. but, should i have stopped back at 5 cogs, freewheels, and 126.5mm? or if not, where along the way?

---

Dan Empfield
aka Slowman

According to this forum, it stops with Hed Jets, rim brakes, and good brake pads.

Bring on new technology. How many of you spend $1000 on a new iPhone every year?

---

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

the disc brake topic is really depending on a few things:

expendable income, and space.

i own a touring bike with rim brakes. good for long haul rides as well as local commuting. i picked up a road bike with disc brakes recently and will pretty much ride it over my tri bike for all rides until the last 4 long rides prior to my race.

the goal is to ride my race bike for tuneup events, long training rides and racing. thus, i don't really need the extra breaking power (though i'll never buy another road bike without disc brakes lol).

awesome job on the testing. really well written. i was already planning on picking up a tactical next season, this further helped me make my decision.

john

Put another way, a debate about planned obsolescence is really a discussion that is separate from the discussion of disc brakes on bicycles.

I remember the very, very, very awkward transition on Apple computers between OS 9 and OS X.

At that point, Apple forced you to have both operating systems running side-by-side on separate partitions. For certain applications, you had to start up OS 9 in so-called "Classic" mode. It was really terrible there for a stretch for us Mac lovers. But eventually all developers moved over to the new kernel and codebase for OS X, and the rest is history.

If Apple had stayed wedded to need for backwards compatibility, they never could have gotten to where they are today. Microsoft - for a long time - was hamstrung by the need to support Windows 95. I mean, wasn't it just last year or so - almost 20 years later - that they announced they were suspending support for Windows XP? And I wonder what it cost them in terms of their ability to stay competitive.

This debate rages in every industry. When the change is first made, the performance benefits NEVER are "worth it." But if you waited for them to be worth it, they'd never be worth it, because a big part of how they come to be worth it is because of a commitment to developing on an established platform.

Karl Hall, who was a wheel engineer at Zipp, put it to me roughly this way:
- over the next five years, the bike industry could optimize rim brakes further and reach a performance level both in terms of braking and aerodynamics that are better than where they are at now

- but over the next 10 years, rim brakes will hit a ceiling that disc brakes simply will not.

Right now, I actually think it's pretty impressive - and surprising - both how good and how aero disc brakes are considering how early on we are in the development cycle.

But it's sort of silly, I think, to continue rehash the planned obsolescence debate...

---

"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Not necessarily (but at least partially), no, and no.

---

http://bikeblather.blogspot.com/

The point of including that was to reference the very sharpest end of the field. His Orbea at the time would have cost a couple of mins (new one doesn't).
Doesn't really matter about the athlete or bikes present on the day though - just showing what the differences are at near 45kph - as that is where equipment differences become meaningful.

Probably not a good analogy to use...after all, one can easily (and I HAVE) take a modern rear wheel designed around 130mm spaced 11sp drivetrains and run it in a 30+ year old frame designed around 126.5mm spacing and 6speed , and using 8 speed shifters/cassette...with the only "difficulty" being having to gently spread the dropouts apart slightly during wheel installation. In other words, there is a LOT of forwards/backwards compatibility over the majority if the time frame you mentioned.

It's not so much about the "march of technology" in and of itself, but about the "step-change" required for a feature set of arguably no performance gain for certain applications. It's that simple...

---

http://bikeblather.blogspot.com/

P5X already has that to a degree. This topic won't get really interesting until Argon18 find a way to put their hidden disc caliper into production.


I'm not anti disc. I'm just ambivalent about them. Getting a faster bike out 5 years of R&D should be expected, regardless of brakes. It's just how you set the parameters you design to. Cervelo have always been the kings of low yaw, which is why they have been the fastest TT bikes - because a bunch of other brands were optimising for yaw conditions that are extremely rare. Now they've optimised a non UCI design for discs and supporting the energy requirements of a small army. Which is probably not going to yield the same result as 'let's make the fastest UCI legal TT bike we can'

Given how poorly Tririg brakes stop me I am keen for consistent, powerful braking on a TT bike. I just don't want to give anything up from the P5.