Project Cieo, The World’s Fastest (and Most Uncomfortable) Tandem

@LaDeekus
Depends on what they had for lunch.

PAUSE

Don’t Shard in My Face…

Highway to the DANGER ZONE….fart fart fart

Kmp
Km
Kmph

???

I call the upper bunk

“Kilometers per hour” is abbreviated “km/h”.

Thanks for the writeup, hadn’t heard about this project. Looks like they should be able to make it. The hour record is over 90 km for a single seat streamliner, a tandem like this should be able to beat it.

WG – at 100 kph, aero is EVERYTHING.

The drag force is 4x higher than when you ride at 50 kph, and 16x higher than at 25 kph. How often do you notice mechanical friction at even 25 kph?

@WG: What Androo said. At these speeds, aero is pretty much the only thing you care about. Drivetrain and rolling resistance is insignificant. A single chain setup on a normal bike has minimal resistance, and even if this ride has 4x that, it’s still nothing to worry about. The drivetrain drag stays the same with increasing speed, so the faster you go the less it matters, relatively speaking.

They could have saved a lot of time and money by purchasing an Air-Spear…

Sure seems like more frontal area than necessary to house a tandem and I don’t agree you can ignore other losses when you’re trying to set records. Don’t discount that these riders have to perform for an hour either. On the plus side, the right rider may prefer the lower bunk 😉 My guess is there’s room for an air freshener.

Where most tandems benefit from the second rider hiding in the slipstream at the expense of length, this solution grows the height and frontal area to shorten the wheelbase. Compared to other single rider efforts I’ve seen, it looks tall and uses smallish wheels. I’d like to see a study that shows they’ve made the right tradeoff there.

No need to get worked up over the drivetrain though. That’s a cost you’re happy to pay.

@craigsj I don’t think anyone is ignoring losses here, it’s more that one should not do anything to optimize 1% of your losses, when it will negatively affect the other 99%.

Interesting about shape tradeoffs. I don’t see a any way to significantly reduce height that doesn’t double the length – that has to have lots of consequences. Also this design puts the shoulders, widest part of the body, centrally so that the tail can taper off nicely. With the riders lying in line the tail must be even longer to get the same taper. I think you’re right that aero would be even better if it was lower, but then you have issues with the handling, construction and transport of a 6-7 meter long vehicle.

Needs more Graham Obree.

I wouldn’t want to be the guy on the bottom. If anything goes wrong he’s perfectly positioned to get his skull crushed, castrated, and mangled at the same time.

call it please don’t fart in my face.

This is an amazing and successful machine. Already the fastest tandem for the hour. Not far short of the solo record. If you want uncomfortable, try conventional TT bikes. When I raced, I found that aero improvements were worth the pain and the power loss. Still went faster hunched as tight as I could. Taught myself to brush the top tube with my knees.
Both riders in the cieo machine have a much more comfortable position, but in work by Sam Whittingham, 200m record holder until last year, he produces more power upright, but then he used to be Canada track team. The aero diference is huge. When I first rode a streamliner round the old Eastway, it scared the hell out of me. When I did a private 10 TT in a basic streamlined machine they put me off first. About 21 mins later they were shaking the watches to see if they had gone wrong (before digital). Sturmey 3 speed, undergeared and a fabric fairing.
I was race director for Battle Mountain twice, despite being a Brit. The shapes keep getting closer to highly laminar. The bikes have less resistance than 1 car wing mirror. There is quite a bit of convergent evolution. Most of the fast bikes use cameras and screens tosee ahead.

If it was a thee wheeler, the bottom rider could have faced forward then the drive chain would be shorter.