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BLSTIC 04-20-2015 11:33 AM

Aero-bike - why have I not seen this?
Craig Vetter has some interesting stuff going on. A pioneer in motorcycle comfort and efficiency. He also had a hand behind these two machines.

Now what I find most interesting about these two machines is the rider layout. My Giant Revive has the same layout. Upright, arms forward, small wheels, rider towards the rear of the vehicle.

Also I noted that the frontal area probably isn't that much greater than a normal bike

So is there some reason I don't see semi-streamlined upright bikes doing the rounds around town? I can already do 50km/h on my revive while drafting big boxy vehicles in the normal seating position (cadence is unsustainable, but the power level isn't). 35km/h intermittent maximum without drafting. 20km/h comfortable on level ground.

Because of the moving feet I feel that covering the lower pedal stroke would be unnecessary (the feet are down exactly half the time on one side at the time, meaning that you need 4x the aero improvement to justify the extra frontal area).

Any thoughts? Is this a bike worth commercialising?

Sven7 04-20-2015 12:04 PM

Not worth commercializing because 'normal' people don't like to spend extra money to look 'weird'. This is an enthusiast thing. Vetter had trouble selling his nose cones, and you saw how effective they were!

I wonder how the side winds would be on a recumbent. Fully recumbent faired racing HPV's have a hard time staying upright in winds. If you're thinking about it, I'd say strap a large piece of foam core to your bike and see how bad the sail effect is. It'll be hard to ballast the front end as Vetter did for stability, so you'll have to do some testing.

All in all, I'd say just buy a velomobile.

BLSTIC 04-20-2015 12:09 PM

Buying is an option, but on my end of the globe they are hellishly expensive. I plan to build one eventually anyway. But this could be an interim, or at least a way to chase down roadies in comfort

Sven7 04-20-2015 12:19 PM

They're hellishly expensive everywhere. It's just the comparison with other options that changes. :)

As for chasing down roadies, you're on your own, buddy! Aeromod your heart out and hope for the best.

Grant-53 04-20-2015 12:44 PM

We did a thread on this bike and there are possibilities for aeromods on any machine. Ideas this different take time to overcome traditional beliefs, many of which are based on assumptions that no longer apply. People are concerned about crosswinds and these can be taken into account with sound analytic methods. The more I ride with my fairing the more positive responses I get. At this point it becomes a marketing effort once technical issues have been addressed. Consider both Craig and I have been working on these types of vehicles for years.

NeilBlanchard 04-20-2015 10:44 PM

The leg position and the seat being back on the blue bike with the small wheels - means it isn't likely to be easy to ride. Ideally, your knees are almost fully extended with your foot as part of that extension, and having your legs under your body mean you are getting much better power into the pedals.

There are a fair number of bikes with this general layout:

Many are folding designs.

Grant-53 04-22-2015 09:28 PM

A Moulton Linear II bike with a vertical wing full fairing was clocked at 50+ mph.

Back angle is related to frontal area so to reduce drag one needs to lean back as in a recumbent or lean forward as a triathlon or TT bike. The marvelous Vetter Challenge fairings are costly and a bit heavy for a human powered vehicle.

Sven7 04-23-2015 10:45 PM

Is this what you're talking about? Liners 1,2,3

I think it would be worth exploring ballast methods for stabilizing HPV streamliners like Vetter did with his motorcycle, but of course most cyclists would fret at the thought of deliberately adding extra weight to their bikes.

X2 on back angle. You run into practicality/comfort issues both in the drops and lying down on your back, so it's a compromise either way.

We don't have to worry about 100mph wind with bicycles, so of course the fairings can be made of lighter "composite" (anything from paper products to crabin fraber) materials. Of course, the really hardcore HPV racers build monocoque carbon streamliners that allow driver ingress by splitting in half* like a plastic easter egg. Weight and complexity might be saved by incorporating ideas from that into a commuter.

*Warning: Chainring porn :D

bhtooefr 06-18-2015 01:37 PM

It's worth noting that the Giant Revive is part of a "semi-recumbent" or "crank forward" class of bicycles. The issue with the crank forward layout is that the natural aero is almost as bad as you can get in a bicycle (Dutch bikes are probably worse). However, it allows getting a foot down easily while still getting full leg extension (which can't be said for conventional bicycles), it's more comfortable than a conventional bicycle (but less comfortable than a recumbent), and the layout enables the use of conventional bicycle parts - it's just got the crank a bit further forward.

Also, re: power into the pedals, if you have low power output, you can get more power into pedals directly underneath you (because you can use different muscle groups to get weight off the saddle and then your body weight helps add torque), but if you have high power output, you want a seat back, and the further ahead of you the pedals are, the better, because you can then brace against the seat and provide much more torque than your body weight allows.

RedDevil 06-18-2015 02:32 PM

Ah, Moulton bikes. If I had one I'd park it in the room, just so I can look at it.

I mean, look at it...
There is so much going on in and around that frame.

My dad has an AM20 and two older models... Geez!

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