Hopefully some of this comfort tech makes it into future tri-bikes. FWIW, this bike doesn’t strike me as an “aero-brick” by any means.
I like the idea, and close up shots of the suspension module give me the impression that you can screw/unscrew it to an extent to fine tune how much travel there is.
The problem that I have with it is that the chainstays are pretty skinny in order to accommodate the extra vertical flex.
I’d be surprised if power transfer hasn’t suffered as a result.
Liam
Power transfer isn’t going to suffer man.
Power transfer isn’t a thing.
I’d be surprised if power transfer hasn’t suffered as a result.
Liam
I like how the front triangle and fork are at least semi-aero, possibly very aero.
Isn’t this the same sort of thing that Trek did with some of the Discovery team bikes about a decade ago, it was borrowed from Klien right? The domane system does seem more clever in terms of restricting the flex to only bumps.
Genuine question. Why not?
If the frame flexes/twists more as a result of pedalling forces, then the carbon is absorbing more energy. Energy that isn’t being used to spin the rear wheel.
Even if there is a return of energy when it flexes in the opposite direction, you have still lost some.
Like I said, this is a genuine question. I’m happy to learn and be corrected if you can show me evidence that I’m mistaken.
Genuine question. Why not?
I think the general idea is this:
Yes, power transfer will suffer.
But maybe by 1/10 of 1 percent.
But you will gain 2-5 percent from better rear traction on roads (except those smooth as glass).
And from your rear staying in your saddle a tiny bit more on those roads.
So, overall, the gain is nontrivial.
(numbers are totally made up, but they’re likely not far off)
- think about which way the frame would flex relative to pedaling forces
- carbon leaf-springs are very very efficient
Read here: https://fairwheelbikes.com/…-bike-crank-testing/
By summing the elements’ strain energy values, we can get the total strain energy for the entire crank and half BB spindle. The total strain energy of this crank under a 250-lb pedaling load is 4.604 Joules. As a unit, Joules don’t do much for most cyclists. We can convert them to a more useful unit by assuming a cadence of 100 RPM. At that cadence, this half-crank soaks up 7.67 Watts. The right-hand crank is usually stiffer than its left-hand counterpart, so it stores correspondingly less strain energy. So rather than doubling the left-hand figure, we’ll round down a bit to 14 Watts for the entire crank/BB axle system. 14 Watts might sound like a lot, and it is. But let’s keep in mind that this is a 250-lb force applied 1.67 times per second. A rider applying this force over 160 degrees of crank rotation produces an average power of 880 Watts, which few of us can sustain for long. And 14 Watts out of 880 is 1.6% To put this in perspective, if you were pedaling along at a steady 300 Watts, your crank would be absorbing 4.8 Watts of your effort. But those 4.8 Watts go into winding up your crank “spring,” which will spring back with nearly all the energy that was spent winding it up.
I’m too lazy to find/link a read on the energy efficiency of springs but you can find that easy enough on your own. Keep in mind there’s a big difference between something like a carbon leaf spring (this system) and a gas shock used on a suspension MTB. Those will soak up and dissipate energy, hence the lockout feature on so many of them.
I like how the front triangle and fork are at least semi-aero, possibly very aero.
Isn’t this the same sort of thing that Trek did with some of the Discovery team bikes about a decade ago, it was borrowed from Klien right? The domane system does seem more clever in terms of restricting the flex to only bumps.
Similar except for the elastomeric unit. On net, this is probably very similar to the Domane but with greater tuning potential (just swap the elastomer) and with better aero (safe guess).
This looks to be aero enough to be a serviceable tri bike but the seat tube looks too slack to do anything about
Any energy in frame flex probably will be made up in other ways.
On a perfect road a bike like this probably would be slower than the normal Dogma. Its heavier and some energy would be lost due to the frame flex. The amount of energy loss is probably very small.
The cobbles however are a far from perfect road. If this new frame keeps the rider from having to absorb as many vibrations with their legs it might keep them fresher and increase their chance of winning the race.
I kind of wish I had a K8-S right now. In 2 weeks ill be in Belgium getting my first taste of the cobbles. My BMC Team Machine is pretty compliant, but probably won’t be nearly as comfortable over the rough stuff as a bike like the K8-S or the Trek Domane.
Power transfer isn’t going to suffer man.
Power transfer isn’t a thing.
I’d be surprised if power transfer hasn’t suffered as a result.
Liam
people said the same about the trek domane that fab used to kicked their butt…
I accept this line of logic, and the principle is most likely right even if the numbers themselves exist only to illustrate the point.
What I didn’t understand though was Jack’s comment “Power transfer isn’t a thing”. As if it made no difference whatsoever.
I usually find Jack to be a very knowledgable commenter, so it gave me pause when he said it.
- Not much power gets absorbed by frames, even ones considered flexible
- The vast majority of that power comes back
How much power exactly is actually lost? Small enough that nobody can measure it reliably, and people can measure pretty well these days.
So yeah, no difference at all from the stays I think is fair.
Hell the shock itself might waste more energy heating up the fluid/gas in it =)
I accept this line of logic, and the principle is most likely right even if the numbers themselves exist only to illustrate the point.
What I didn’t understand though was Jack’s comment “Power transfer isn’t a thing”. As if it made no difference whatsoever.
I usually find Jack to be a very knowledgable commenter, so it gave me pause when he said it.
- Not much power gets absorbed by frames, even ones considered flexible
- The vast majority of that power comes back
How much power exactly is actually lost? Small enough that nobody can measure it reliably, and people can measure pretty well these days.
So yeah, no difference at all from the stays I think is fair.
Hell the shock itself might waste more energy heating up the fluid/gas in it =)
I accept this line of logic, and the principle is most likely right even if the numbers themselves exist only to illustrate the point.
What I didn’t understand though was Jack’s comment “Power transfer isn’t a thing”. As if it made no difference whatsoever.
I usually find Jack to be a very knowledgable commenter, so it gave me pause when he said it.
^^ And that’s the Jackmott that I have come to expect
I don’t mind being told I’m wrong, it’s something that we all need sometimes. Some of us more than others.
“It’s negligible, we know because we have tested similar situations” is a perfectly fine answer. “It’s zero” (or words to that effect) requires backing up a bit IMO.
Cheers,
Liam
Not just Disco team bikes…it was a feature on some Pilot bikes beginning in 2005…called S.P.A. technology, for Suspension Performance Advantage.
It’s a nice bike, comes with the arrogance to be expected from Team Sky:
“This is the first time anyone has gone out there, looked at the demands of the cobbles, and made a bike specifically for that job. It was really noticeable in testing between the guys on the K8-S to the others that weren’t. It gives us lots of confidence and a huge advantage on the cobbles.
Read more at http://www.teamsky.com/…#MxJVo0UVxFloOegi.99
Yeahhh suuuure, why didn’t anyone before look at those cobbles and design P-R specifix bikes. Oh wait, they did.
Somewhere I read that they showed an 8% increase in speed at constant wattage over the cobbles with this system and that the riders couldn’t feel any loss of power on the flats.
Not just Disco team bikes…it was a feature on some Pilot bikes beginning in 2005…called S.P.A. technology, for Suspension Performance Advantage.
Moots has had their YBB (Why Be Beat) frames for like forever.
Yes you are correct. Carbon is one of the best for return of energy (like a spring) but if a part flexes, some of that energy goes into heat or torsion -creating perhaps friction in the drivetrain or mistracking of a wheel etc), which is at ne loss. Would be more of an issue at high load, so for climbing and sprinting. It just might not feel right either, which to me is the bigger deal.
But this is a for-purpose bike.
You know on my Pinny I put a Most integrated carbon stem and handlebar combo (from ebay). Looks really cool too. I got it because I hated the orig bars, but geez that upgrade is so smooth, I am looking for carbon bars for my Titanium ride now as well.
I build my own saddles using Ultralon EVA which is way better at isolating road vibration that anything I’ve tried stock. I am building a few more this week for some new bikes… but I also thought that with a slotted hole, a adjustable urethane bump stop/pin system you could create an elastomer suspended seat post.
Yes you are correct. Carbon is one of the best for return of energy (like a spring) but if a part flexes, some of that energy goes into heat or torsion -creating perhaps friction in the drivetrain or mistracking of a wheel etc), which is at ne loss. Would be more of an issue at high load, so for climbing and sprinting. It just might not feel right either, which to me is the bigger deal.
But this is a for-purpose bike.
You know on my Pinny I put a Most integrated carbon stem and handlebar combo (from ebay). Looks really cool too. I got it because I hated the orig bars, but geez that upgrade is so smooth, I am looking for carbon bars for my Titanium ride now as well.
I build my own saddles using Ultralon EVA which is way better at isolating road vibration that anything I’ve tried stock. I am building a few more this week for some new bikes… but I also thought that with a slotted hole, a adjustable urethane bump stop/pin system you could create an elastomer suspended seat post.
Or you could just buy a Thudbuster or one of the other seatpost suspension solutions and then not have to deal with any supposed inefficiencies when sprinting or climbing out of the saddle.
I checked out the Thudbuster design - imo it’s bonkers. You just have to look and what the (european) engineers have done for NVH on automotive suspensions. This Thudbuster is a resonant circuit designed to roast your a$$. ie your a$$ is the shock absorber in the chain. By that I mean the damper.
So pass on that one. My proposal is isolating and damping (grease to seat tube) and would cost like $20.