Recumbent - Rans Aero advantage over typical "roadie"

does anyone know how much (if any) aerodynamic advantage Rans bikes have over your typical road bike?(and i mean UNfaired to be fair:D ) it would seem to me that the rans bikes with the lower seats would have the greater advantage (on the flats and downhill of course). Is this so? what about a rocket or v-rex? My guess is that they're about the same with maybe a little advantage going to the 'bents. I know a huge factor is seat recline angle, but most rans seem to prefer a more upright position: you see less of your legs pedaling and more of the road-it's like the closest a 'bent can get to a roadie point of view (of course it's better cuz you don't feel like you could go over the handlebars).Also, at what angle do you start seeing increased speeds. could you just take any bent, recline the seat more and start to see higher cruise speeds, etc.? thanks!

I really can't see any rockets or v-rexes unfaired keeping up with any roadies around here, even on the flats. Unless the engine on the rocket is exceptional, keep looking for a recumbent with a more laid back position. John might have a better explanation of what the v-rex can and can't do against a roadie.

Hi Rabbitt!

As I understand it, wind resistance is everything above about 13-15 mph. I saw some post here on BF (if it's to be believed) that said that 12 mph is the "break" speed at which you're spending equal energy moving the bike (not counting wind resistance) and overcoming (actual) wind resistance. Everything above that speed requires almost exponential power increases. Really fit folks can maintain 25 mph or more (on DF bikes) on flat pavement for a while, but the energy expended is tremendous.

To speak to your question, yes, I think that reclining the seat on any recumbent will decrease wind resistance and increase speed for the same rider output.

Yes, there is an aerodynamic advantage. Here are a few websites that discuss it:

http://www.hpv.on.ca/recumb.htm

http://www.wisil.recumbents.com/its_the_bike.htm

http://www.biketcba.org/TRICORR/misc/faq.html

There was recently a new world record of 53.43 miles (85.987 km) in a one-hour ride.

http://www.ihpva.org/dempsey_macready_prize.html

The record for a diamond frame is 56.375 km, set by Chris Boardman of England using an aero-style upright frame that has now been banned by the UCI. Since this ban, the fastest one-hour finish was just over 49 km in one hour (using an Eddy Merckx type standard diamond frame bike without aero wheels).

To get a better idea of the advantage, see this site:

http://www.mueller-hp.com/windtunnel.htm

Table 2 of that paper shows that the VR40EU by Vision had a 4.7% advantage over a road bike, with the rider holding the top of the bar. Adding a Meuller fairing to the VR40EU helped a lot, giving that biker an 18.9% advantage over the road biker on the top bar. A road biker in an aero tuck had a 32.1% advantage over the road biker on the top bar, but a Vision VR65ET (Saber) had a 36.8% advantage over the same road biker on the top bar. This is at 20 mph; the table also shows the advantages at 30 mph, which are more dramatic over the upright rider on the top bar. So, it depends upon position, and the bike itself.

On a personal note, I am not the fastest rider around, and I ride a Rans Stratus with a Meuller fairing. I also ride a Trek 1420 aluminum diamond frame bike, and a Schwinn LeTour. The Rans Stratus has a great advantage in high wind conditions, which I sometimes see on my commute home in the Portland, Oregon area (actually, just to the west, the Beaverton-Hillsboro area, but few people recognize those cities unless you're into high tech;)). We sometimes get east winds that are in excess of 35 mph, and here is where the aerodynamic advantage really helps on my commute home. It also takes cross-winds better than a diamond frame, even with the fairing--I'm sitting closer to the ground, so the wind doesn't have the leverage it does on a diamond frame bike rider. And a wind from behind really catches the fairing, and gives an added push--the best of all worlds.

John

My experience with a recumbent in general is mixed. When I first switched to a bent, I lost great deal of time on my hour-long commute, which has some large/steep hills and also fairly flat areas. But after breaking in new muscles, my commute time was back to normal.

Overall, I think the diamond frame bike has an uphill advantage, while the bent has an obvious advantage on flats, downhill, and into the wind. I've been able to overtake just about anybody downhill, if I have a mind to. In fact, many times when I come up behind another cyclist riding downhill, I not only have to stop pedaling, I have to brake to avoid overtaking. One guy drafted me downhill, and when he finally passed me, he said about my bike, "I like it!" I also like the way my bent cuts down on the effects of wind.

Another advantage of the diamond frame is balance, but that again seems to get better on my bent with practice. An advantage of the bent is the higher pedal position, which actually allows me to pedal through most turns without stopping. Also, the seating position is more natural and allows me to see more.

Specific to the original post about RANS Rocket and V-Rex, those are not particularly aero bikes. A Force-5 gets the feet up enough that a pretty reclined position is still closed enough for power. Here's a real-world example:

I ride a Rotator Tiger, a dual-20 bike which could be compared to the Rocket. The Tiger's crank, however, is 8" above the seat so I can recline the seat quite a bit and be comfy. On my local hill, I brake before hitting 50 mph coasting down. Recently I took my wife's unfaired Stratus out on the same hill. I ride relatively reclined on that bike, but still much more upright than the Tiger. I was powering down, pedaling all the way at a top speed of 35 mph. There's the aero difference for you, and you don't get it with a low crank and upright seating unless you use an *effective* fairing, which probably means a body sock.

The Stratus is a beautiful bike and a joy to ride - ridiculously smooth yet I don't feel like I'm giving up power and it handles confidently at all speeds. But in my experience it has no aero benefit over a DF. The Tiger, with small wheels and a laid back riding position, seems to roll down better than a DF with the rider in the drops.

Hope this helps,

Being a former DF rider who rode a V-Rex exclusively for 4-5 years, I'd say that an unfaired V-Rex with the seat well reclined is the aero equivalent of a DF rider riding on the hoods. I could get a slight advantage over the uprights if I put a good fairing on it, and the few times I rode with a full head-out coroplast fairing, I blew them away. But that made it harder to transport and made it so it didn't feel like a bike anymore, so I went with minimal fairing and accepted the lower, DF-like speeds.

A high or low racer will be faster than a V-Rex or Rocket, unless you go the full fairing route on the RANS. And of course, if you fully fair the racer, it'll be even faster; although fairing a racer brings on its own problems.

thanks alot guys! It's so great to have the help of people like you. (all cheesyness unintended)

I'd like to add that my choice of the Rans Stratus came after I had test-ridden most of the available recumbant bicycles, both long wheel-based and short wheel-based. Most of the short-wheel base bikes had too high a BB, and were very difficult to get back into on a hill at a red light. I use my bike for commutting, and really need to be comfortable in traffic with it.

I rode the Stratus many times during these evaluations, and compared it to the Easyrider bikes. I actually liked the Rans Stratus better, not because it is faster (it's not), or handles easire (the Easyrider bikes are top for that too), but because overall, for the price, it is a rugged bicycle that is very easy to use in traffic, easier than the Easyrider (and much easier than any under-seat steering bike) to walk with, and it will haul a heck of a lot of stuff. I have mine set up with front as well as rear panniers, and carry my bicycle tools, lock, etc., in the front ones. With 26 inch wheels (for the Stratus), I can haul very heavy loads on fairly bad roads without worry about blowing a tire too.

The fairing does help a lot, including rain protection--I only get wet in heavy rain from about the chest up, and that's better coverage than an Easyrider with a fairing. The Stratus I have is an older model, before Rans "improved" the steering by taking out the "tiller effect" and incorporating more of the Easyrider steering geometry. But what this does is to raise the steering height, which raises the fairing height, and decreases the streamlining. It also increases the possibility of knee bumping when turning, and decreases the convenience of walking the bike.

Every bike needs to be evaluated by the rider to make sure it meets his/her needs. This is what I came up with, and by putting it into words, perhaps it will help some others out too.

John