This will be fun to watch.

Did you see the repeat runs with the rider?

Methinks they need to find someone who can hold a position more consistently...yikes...

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http://bikeblather.blogspot.com/

Yikes!

Didn't the P4 thread suggest P4 > Zipp 2001. I'm not 100% sure about the Dimond's changes, but man. That's a serious claim.

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My Blog - http://leegoocrap.blogspot.com

I have nothing to add really, but I sure do love the bike.

Seat of the pants dyno says
I did go 26mph avg on the rolling course of an Olympic bike split on just 260W AP. I thought that was crazy low wattage for the speed.

It's not worth much, but it's something.

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@christopher_borden •
Spinning Spoke • Dimond Bikes • Flo Cycling • Castelli Cycling

Yeah bet they think they were clever by getting the rider into the "same" position. The small changes in his form from run to run are affecting total drag more than the frame design. The systemic error is greater than the effect they are trying to measure.

your bike looks great if nothing else ;)

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My Blog - http://leegoocrap.blogspot.com

That's what I'm saying!
Honestly, everyone ask me about the bike, and I point them towards the website and the tunnel data, tell them about lower rolling resistance, and tell them about the magic the beam maybe maybe might be voodoo'ing out of t2.

But realistically, races are only a handful of times a year. The rest of the time, it's a freakin cool bike that has a smooth, comfy ride that feels pretty good on Alabama back roads.

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@christopher_borden •
Spinning Spoke • Dimond Bikes • Flo Cycling • Castelli Cycling

Are you talking about the bike, or your tires/tubes/pressures when talking about rolling resistance?

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http://bikeblather.blogspot.com/

Paging Colby Pearce...paging Mr. Colby Pearce. ;)

Variability aside, though, I don't find it all that surprising that the Dimond is faster w/o a rider, but no better than the P5 w/ a rider. The Shiv Tri being significantly slower than the P5 is also consistent w/ other data.

My biggest complaint about the report is that it appears that they based their time-savings claims on the bike-only data...

I was afraid I was using the wrong term, but I figured someone would offer an opportunity to educate me.
I didn't get that from Dimond, rather read it somewhere along the way. But I seem to remember something about the beam offering a similar benefit as tires/tubes by damping the vertical movement of the rider.

I've asked about this a few times in different places, but never got a solid response.
So, I just call it beam voodoo.

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@christopher_borden •
Spinning Spoke • Dimond Bikes • Flo Cycling • Castelli Cycling

The head position is interesting also...

It's the Faster tunnel... is it maybe not large enough to avoid interference effects with a rider? I've heard this tunnel is relatively poor, anyway.

Odd that even though the results with rider were inconsistent, the P5 was consistently bad. And the Shiv pretty good.

Yeah...just like I say to folks who claim that wider rims result in lower rolling resistance...show me the data ;-)

Placebo works though, too...

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http://bikeblather.blogspot.com/

Page 8 figure 6 for everyone else. What's strange is the Cervelo was very consistent. Elsewhere the Shiv vs P5 data looks right. In any event, the Dimond appears to be a fast bike... plus it looks fast. Isn't looking fast good for 10w at the crank?

I chatted with Chris at Ruster Sports via email earlier this year. IIRC, he said the beam doesn't deflect that much vertically, something along the lines of ~0.5cm.

Not being arguementitative, I just want a handle on it.
But isn't the logic the same?
if the tires/tubes' damping makes faster, shouldn't the beam?

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@christopher_borden •
Spinning Spoke • Dimond Bikes • Flo Cycling • Castelli Cycling

I don't think anyone is arguing the bike is fast. We've known (or at least been pretty sure) the 2001/3001's were fast for a long time.
The question is more... is a little update to that frame faster than today's newest super bikes.
I definitely agree it's one of the sweetest looking bikes (but I'm biased towards that frame...)

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My Blog - http://leegoocrap.blogspot.com

Not the same. When isolated to deflections in the tire, when using tires with excellent Crr, that means a good portion of the energy put into the tire in the leading half of the contact patch is actually returned to the road surface in the trailing half with the small hysteresis losses in the material actually resulting in the "reverse torque" about the wheel axle that we experience as rolling resistance.

Once the energy gets past the tire, then it's just dissipated as heat somewhere in the system.

That's also why it's better to err on the side of slightly too little air presure in your tires than too much. If you stiffen the "tire suspension" too much, you start dissipating energy instead of having it returned to the road surface.

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http://bikeblather.blogspot.com/

It seems the idea is that suspension lowers rolling resistance. Clearly it does not effect deformation of tires significantly. However it does reduce sprung mass, or some such thing. I may not be able to explain the theory, but I know from riding MTB's over rough ground that the suspension makes things faster. If the road is track smooth it clearly won't matter. I could imagine it making a difference on chip seal though. Another thought is that one could run higher pressures before Crr began to increase.

Actually, no. You're talking about deflections of much higher amplitude and much lower frequency on the MTB than with a typical road surface.

Apples and oranges comparison...but don't feel bad, that seems to happen a lot when people think about applying MTB technology to road bikes ;-)

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http://bikeblather.blogspot.com/

So on chip seal roads with large rocks, you don't suppose adding suspension will make a difference? The effect is noticeable in grass with highly inflated tires.

The issue with adding suspension plush enough to handle large rocks is that you're adding enough travel to cause pedal bob. With pedal bob a good chunk of energy will get eaten up by the suspension. Suspension designers have been trying to resolve this issue for ages with products like Specialized Brain and Fox Pro Pedal. In the end, the most effective way to eliminate pedal bob on a MTB is the good old mechanical lockout.

I don't see how the beam can decrease the effective rolling resistance. What it can do is smooth out harsh harmonic vibrations, which would result in less fatigue and more comfort for the rider. That's actually quite a gain to be had.

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Velosurance - bicycle insurance

Like, say, the rocks found in the Arenberg Forest? Bike companies have tried adding suspension over the years, but guess what keeps winning? Regular road bikes with big, fat, low pressure tires.

So the great benefit of snazzy tires and tubes is the energy return as the rider moves beyond the deflection point in the tire?
And
The beam simply damps vertical ossiclations of the rider? You don't think there is any benefit as the beam rebounds?

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@christopher_borden •
Spinning Spoke • Dimond Bikes • Flo Cycling • Castelli Cycling

For what it's worth

From the cockpit
I cannot feel any vertical movement in the frame. Aero, climbing, sitting, standing, whatever. I never feel bob, bounce, spring, or sprung.
It feels plush, like I forgot to air up my tires. It's a smoother rider than my C'dale EVO with the same wheels/tires/tubes.

From the draft
One of my riding buds remarked that the tail has a wee swagger. From his view, he could visually line up the beam with the down tube and "noticed a slight shift with the pedal strokes."
Lots of guys have ridden behind me, he's the only one to ever comment on it, and I cannot feel it nor do I doubt it happens. He said it couldn't be even 1cm of horizontal movement.

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@christopher_borden •
Spinning Spoke • Dimond Bikes • Flo Cycling • Castelli Cycling

I'd like to see Dimond vs. Falco in the wind tunnel.