I lost a TT last year by about 3 seconds to my "30-second man." I did the Strava Flyby on it, and found that he'd taken a technical off-camber, 90-degree turn much faster than I had. Braked much later and carried more speed. That was the 3 seconds. Everywhere else we were pretty much dead even. One explanation is simply skill. But I like to think I'm pretty skilled at cornering. I've done ~200 crits and can take turns to the adhesion limit. I just have very little confidence in my TT brakes. Which have a whole host of issues that all add up. Tiny levers with a different pull ratio than most calipers are designed for. Boutique after-market aero calipers that aren't the best at braking. Byzantine cable routing to the rear.

Also many (most?) triathletes use their race bike as their training bike. So it's not necessarily about racing. Everyday stopping in traffic, dog running out in front of you, etc, is a consideration.

I was on the TomA disc-hater club for a while. But this Cannondale dude has me re-thinking that. I probably won't *seek* disc brakes on my next TT bike. But neither will I rule them out as a starting point. as long as I have data at least as compelling as this.

Not always. I swap wheels on gravel bike fairly regularly with no issue.

Tom A will come on here soon and tell the Cannondale engineer he is wrong ;)

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

Sometime you get lucky. Sometimes you don't. I needed a spacer to get rotors on the two wheelsets on my MTB perfect.

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Suffer Well.

So a bike that was designed for disc brakes by a company heavily vested in disc brakes tested faster with disc brakes? Nothing but a fancy marketing exercise as far as I'm concerned. How much faster was the P5-6? Show me an optimised comparison like how Cervelo attempted, and failed, to provide.

I hope so. Because I think it'll be more than a fair fight. Usually TomA's combination of genuine technical knowledge combined with condescending tone will cow most people. I get the feeling that this Dr. Barry is totally equipped for disc-vs-rim MMA action.

If anything can stop TomA from repeating the move-the-disc-to-the-center-and-then-towards-the-rim joke for the 1000th-time I'm all for it.

"if it turns out the disc brakes are aero neutral to rim brakes in an independent test, is that reason enough to upgrade wheels"

i've been hearing the "do we need to upgrade" argument for 40 years, and for all 40 years it's been valid. still, we wouldn't be here, with 11 gears (or 12), with clincher aero wheels, etc., unless these questionable new platforms won out.

as we've moved from 5 gears to 6, to 7 and up to 12 (which is where we are now with 1x) we've often needed to change our equipment; upgrade our wheels. as we've moved to 650c and back again, same thing. tubies to clinchers.

no need to upgrade. but what about those just starting out? i think if i was starting, getting ready to invest in my first tri bike, it would be a tough choice. in a year, yes, disc all the way. maybe by this upcoming spring. there won't be a need to spit can all my old wheels. no wasted investment.

but it's always going to be like this. in order for there to be a better standard we all use, that better standard was at some point a new standard, displacing an existing standard.

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Dan Empfield
aka Slowman

LOL....yep, those dirty bastards in the bike biz are out to force you to ride discs.

It's a conspiracy.....FIGHT THE POWER!!!

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Chicago Cubs - 2016 WORLD SERIES Champions!!!!

"If ever the time should come, when vain and aspiring men shall possess the highest seats in government, our country will stand in need of its experienced patriots to prevent its ruin." - Samuel Adams

Pretty well executed marketing exercise, though.

P5-6 comparison is a bit of a flawed comparison because that'd be comparing bikes more the aero effect of different braking setups.

And leave the P5x debacle out of this. That's a whole other issue.

Actually that was specific to Cannondale. They've embraced road discs with unmatched enthusiasm in the bike world. Take a look at their catalogues from the last two seasons and show me another brand with as many disc offerings. Surprised they haven't kitted out their track bike with them.

Haha, now that is gold.

What I want to know is how much of an impact Cannondale's headtube/fork design contributes to the drag savings on the disc setup. Or are they saying slapping on disc calipers and rotors instead of rim calipers doesn't make much of a difference.

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yeah, most TT bikes are better at going fast than stopping - that's what they're designed for. i'm not convinced that its the brakes that are the issue though, especially given that its often the same shimano direct mount brakes that work a lot better on road bikes. TT bikes brake badly because of the minimal levers, the inappropriate angling of those and the bars you want to be grabbing them against, the carbon rims and most of all, the forwards position the geometry puts the riders weight in (especially tri). hydro discs will get around some of the bar/lever issues by requiring less force but if you're still unable to get your weight in the right position then you won't stop (but your bike might).

i'd certainly be happy to get better braking though, for training more than racing. this test suggests that the difference is at least not huge (relative to other factors) and i'd expect aero discs to improve in time. the big issue is persuading everyone to buy new wheels but thats not a factor for the stream of new entrants to the sport who will be easily sold on discs

Hello James Haycraft and All,

"If anything can stop TomA from repeating the move-the-disc-to-the-center-and-then-towards-the-rim joke for the 1000th-time I'm all for it."

Was that a joke?

http://www.slowtwitch.com/..._Aero_Drag_6073.html

Comments near the bottom ......

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Cheers, Neal

+1 mph Faster

I don't know. But assuming that prototype bike used in this test is the same as the image of the P4-looking bike we've already seen there's no glaringly obvious "disc optimization" on that frame. It's a simple classic front fork and rear triangle. At least by the eyeball test. Conventional-looking headset. There's none of the fancy caliper-shroud stuff that Parlee came out with.

But that assumption could be wrong.

Right. It's death by a thousand cuts.

Leaving the whole racing issue aside, do people also not train on their bikes?

The majority of the time I spend on my tri bike is training, not racing. If there's a product that's out there that makes my life easier during most of my riding and, seemingly, doesn't hurt while I'm racing, why wouldn't it be a good idea?

My feelings about Di2 are similar. During races, it's of limited use to me but it makes training rides much easier to deal with.

Not big...HUGE. Especially if you aren't monitoring "power to rotate".

Also, why not an Omega under the BB? How about a simple extension of the DT to "fair" that area? Heck, frame designers do that for Di2 batteries...

Here's the thing...as detailed as it is (and I fully appreciate that), this test was basically "duct taping" rim brakes onto a bike that was designed around disc brakes, and not even optimizing the hubs/spokes for the rim brake advantages in that regard (Yes, they note that, but then don't try to quantify it.)

What if you did the opposite and glued some discs onto a Speed Concept or P5-6, or something else with much better brake integration than what was tested? How would you expect the results to come out?

So...in the end, isn't this test just illustrating the point that if you don't design around the braking system chosen in the first place...and that if you then swap things...it might not be that great??

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http://bikeblather.blogspot.com/

Possibly...and if that's the case, one would think that the fork lowers, especially the left side, would be "beefier" than they would need to be otherwise...thereby "sandbagging" a bit.

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http://bikeblather.blogspot.com/

This. We've often seen brakes decrease overall drag of a frame when compared to no brake, but if a frame is designed to have no rim brake, and you slap a rim brake (or brakes) on it, then it shouldn't be a surprise that drag increases. The surprise should be how little drag actually increased with the rim brakes.

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Jim Manton / ERO Sports

Right...but, that's also one of the few cases where the tests were the most "apples to apples", in that the rim brakes were well integrated into the frame/fork AND the spoke counts were appropriately varied.



Not to mention that the rim brakes used weren't particularly aero (standard sidepulls), so there was a bit of sandbagging of the rim brake setup in that regard...and again no accounting for lower spoke count on the rim brake runs (nor measurement of "power to rotate").



But, are low spoke count disc wheels a good idea? I've got a taco-ed low spoke count MTB wheel which begs to differ (I think I've shown you a pic of it before ;-) BTW, it actually taco-ed WHILE braking.

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http://bikeblather.blogspot.com/

Hope this isn't too stupid of a question from a relative tri newbie. Couldn't you just relace your expensive race wheels to a set of disc hubs to help offset some of the cost is this does become the new industry standard? Obviously this might not be possible on a disc but all other deep wheel sets could it be done?

It's possible to a certain extent, but disc wheels require more spokes due to the braking force near the center. So you'd need a rim with I think at least 24 spokes, most aero wheels go with 20 or less even. And what disc brake aero manufacturers are hanging their hat on is the fact they can create better rim profiles by being able to remove the brake track.

Fixed this for you.

Would this test have been better if they used Andy Pott's bikes that we saw him riding in Hawaii? He raced his TriRig brake set up but was seen on a prototype with disc brakes. The first bike was optimized for rim brakes and the second was optimized for disc brakes. Would a head to head test with these two bikes not be ideal?