Are there new V20s coming out?

[Bill Wightman]

I would offer front assembly, including chainstay, in one piece that was aerodynamic in 6 different sizes.

Yes. That is exactly what should be done. Exactly what I was picturing as I looked at my front triangle with the custom carbon cover over the top third of the wheel. You could integrate a aesthetically pleasing carbon cover with the rest of the front triangle in those six sizes. I would definitely eliminate any carbon layup that does not benefit structural or aerodynamic functions, especially as that structure moves forward. There should be no carbon ahead of the bottom bracket.

Would steering be tricky when flow detaches? I always wondered how magic does it in gusty winds.

One of the reasons that front deep wheels kick in crosswinds is the high drag of the forward moving upper third of the wheel. When you put a cover over this portion of the wheel (and spokes), drag from head and side wind ahead of the steering pivot point is reduced. That is partly why I am comfortable in heavy crosswinds, even though that is not a very efficient wind direction for the bike compared to head-on or directly behind.

Instead of the boom being tubular it would be upside down elongated heart shaped in order to cut through the air like butter or like a snow plough pushes the snow each way as it goes forward.

It seems that the Hammerhead front arc shape (with a clean half-parabolic section) may actually be quite good from the perspective of aero, especially if there was a small skirt that came down over the tire and about 90 mm of radial length over roughly the top third of the wheel. After that integrate the six sizes structurally and sell based on inseam measurement or measurements taken from a kit. I still would have the front triangle no higher than the fork crown, and steering done with a backward facing clamped long stem with handlebars, very stiff with sensitive steering control of the wheel.

 

[ed72]

One of the reasons that front deep wheels kick in crosswinds is the high drag of the forward moving upper third of the wheel. When you put a cover over this portion of the wheel (and spokes), drag from head and side wind ahead of the steering pivot point is reduced. That is partly why I am comfortable in heavy crosswinds, even though that is not a very efficient wind direction for the bike compared to head-on or directly behind.

My understanding is slightly different. It is the change in drag.

Depending on speed and yaw angle to the wind, the airflow over the top third of the wheel is laminar and life is good. If your bike speed reduces or wind angle increases, a point is reached where the wheel stalls due to turbulent effects. This is the snap one feels. My solution is just to ride faster. LOL. A disk up front if one rides fast should almost make you immune to this dislocation under most conditions but when it does happen, look out.

I do not know what effect a fairing would have. The only "tests" along those line was Jan Heine with his superlong elephant tusk fender and there was some Magic data. But no question top third of the front wheel is where all the action is. Lots of drag there. Interesting idea.

 

[3bs]

so, @Bill Wightman hits on some of the key points. i have been doing some more experiments, but time is really my enemy right now. after the first of the year i will know a little more about my schedule, but, don't forget that part of your ride quality in the v20 comes from the frame material, and a large part of what cb has done with the v is to make the bike adjustable by fixing the seat location and putting the adjustability in the front end. this enabled them to make the frame section pretty darn light, have a very solid seat to frame connection, and yet integrate a pretty large amount of adjustability while making the drive train triangle pretty stiff.

@DavidCH have you been sneeking views of my drawings?

trust me when i say that i have been spending a lot of time thinking about ways to make CB bikes lighter and faster, more versatile, and more transportable (and about four other innovations i want). i now have 2 CB frames and 3 bikes that i have disassembled reassembled measured, altered, etc. this is also why i am very interested in what the new bikes are going to look like and what new improvements CB is bringing in this next gen.

if you look at CB bikes, and JM's bikes (of which i have several as well) and M5 (of which i have a couple) it is the study of them all that show both the great common features, and where each thinker has added value. the advantage JM has over everyone else is the bespoke nature of his bikes do not require much adjustability. (they actually have quite a bit, but you have to really study the bike to find where you can get it) that said if you were to retain material choice and eliminate adjustability in a v20 i think you maximum weight savings is under 3 lbs. now on my bike that is 10%, but when you examine combined rig weight (me and my bike) then it is about 1.5%

candidly, i still believe i can bring a very bespoked v20 concept in at 20lbs, but its hard for me to see the all of the improvements as fiscally responsible. io can see several ways to make it more aero, but again, some of it would be at the expense of adjustibility.

 

[3bs]

one other place that you see the evolution of this stuff is in marco's bikes. when i cam across his work, i laughed as it served as a good reminder that there are better minds than mine that have been at work on these issues longer than i have. i was pleased to see the similarities, as it meant i was on the right track, particularly with my love of low racers.

 

[Bill Wightman]

Depending on speed and yaw angle to the wind, the airflow over the top third of the wheel is laminar and life is good. If your bike speed reduces or wind angle increases, a point is reached where the wheel stalls due to turbulent effects.

Maybe I am wrong but I did actually run a few CFD analysis runs of a rotating disk wheel at 30 mph with appropriate surface roughness and both laminar and turbulent effects. I only modelled head-on air flow and any trailing flow I saw was turbulent. I think when we are hit with a strong cross flow then a similarly strong and large eddy formation takes place on the downwind side. The turbulence is there all the time because the tire and leading surfaces of our bikes are anything but smooth with spokes, feet, cranks, dirt, all flailing in the leading smooth air. This eddy formation (vortex shedding) is most severe at the top of the (front) wheel and so has the effect of pushing us over more than steering us off course. We then have to countersteer to get the wheels back under us and before we know it we have moved over three or so feet. That is why I focus on a "locked" arm position and quick small reactions when in a narrow bike lane next to lots of traffic with strong crosswind conditions.

 

[M.J]

I wonder if the V20 frame and front triangle could be reasonably modified (for cost and ease of production) into a REV-style lowracer...
Stretch the wheelbase a little and drop everything down between the wheels with the pedals more out in front of the wheel.

 

[3bs]

@M.J have you been sneaking views of my drawings?

i better get my surveillance cameras up around the skunkworks.

one of the keys to marco's bikes is the proximity of the crank to the wheel. this allows for the drop, and the body position.
also take a careful look at this crank over seatpan height versus what guys like @LarryOz run.

spoiler alert: this observation leads on to the key to a frame that can be disassembled for packing and travel....

 

[M.J]

Dammit, now I'm going to have to figure out how to bypass your cameras
The NoCom has a pretty low BB, also, but it leads to all sorts of problems with chain routing and wheel interference. A MBB NoCom-style bike would solve this. Like the REV does.
Marco also has his shoulders propped up higher than what traditional "high performance" recumbents would do. No laying flat on a 10° seat. I recently built up the shoulder area on my V20 and was struck by how much longer I could produce full power, especially uphill. I think anything you lose in aero by sitting up a bit, especially if it's only from the chest up, can be gained back from producing more power for longer through improved breathing. KOM attempts and hills no longer feel like lighting a fuse and trying to get to the finish before the bomb goes off, but I'm not noticeably slower.
Anyway, that's the wishlist. An aluminum REV with a seat that holds the shoulders up enough that I don't need a neck rest.

 

[M.J]

My bike, if you're curious. Wedge is built from pink insulation foam board. What looks like a neck rest actually sits at the top of my shoulders. I can comfortably hold my head up.

 

[LarryOz]

Marco also has his shoulders propped up higher than what traditional "high performance" recumbents would do. No laying flat on a 10° seat. I recently built up the shoulder area on my V20 and was struck by how much longer I could produce full power, especially uphill. I think anything you lose in aero by sitting up a bit, especially if it's only from the chest up, can be gained back from producing more power for longer through improved breathing. KOM attempts and hills no longer feel like lighting a fuse and trying to get to the finish before the bomb goes off, but I'm not noticeably slower.

This matches my testing results of a steeper seat angle allowing the rider to produce more power. There is a fine balance between areo and power making capabilities. Marco's low racer design is allowing the hip area to be lower and therefore a steeper seat angle that still lets the head be relatively low and areo with respect to the front end and handlebars.

 

[3bs]

@M.J i see you are also looking at my readily available pictures. my wedge is a lot smaller than yours, but the net angle at that point is similar.
the wedge is the key to keeping a low angle for aero and then making power. this is also one of the interesting aspects of the thor seat. it has that upturn. you need that little bit of turn at the top to plant the shoulders. i think this may have been what @LarryOz may have been looking for in the thor wing seat. larry has a unique ability to create power in a more flat position. you see this talent with some of the M5 track racers.

and yes if you look at @markciccio 's bike you see that for all intents and purposes he is pretty well in the air already affected by his front end. his head is up, but not far and he usually wears an aero helmet. also note that he runs a lower bottom bracket than most people subscribe to. since i run my bottom bracket lower and i have the wedge, i feel i can climb better than many, and i also have to sit up a little more because of a trashed stomach valve.

and while i don't have a nocom i do have an m1, and if you look at that bike JM put the rider in the airflow with a reasonable shoulder angle.

in my experiments on creating a v20 low racer that can be disassembled for travel, this is one of the great tensions. a low racer with the seat shape i prefer inherently requires a longer wheelbase, as you are sitting lower and deeper in between the wheels. this does improve the topsides, as you can see with Magic, and the straight power tube is his solution.

go back and look at my work with the hammerhead and you see the similarity. i still say the hammerhead is one of his best framesets ever. i think its issue is in the handlebars visavis the headtube. but this is also what early CB looked like, and the hammerhead steer bars are beautiful.

if you look at a lot of jm's bikes over time you will see the refinement of the front end regardless of the drive location. this is what makes the apache so fast.

i will convert my ideas and my test results to real bikes soon, i just need a little more time and a couple updates to my equipment ( among other things, i really need a new tube bender), and i am trying to get my self into a class to refresh my welding/brazing skills. i think what i have in mind on several of these MBB FWD variants can be best sorted out in metal.

 

[3bs]

examples. see how on frankentrike i have a good power angle for the top 1/3 of the seat?
slightly less on the m1. (older picture. i have a little foam wedge i use now.)

 

[ed72]

Anybody know what mid or high racer is faster/fastest? Arrowhead? Apache? Magic? Mod'd V20? Other?

I failed on my goal to average 24 mph on 140 watts on my M5 although I came pretty close. I ultimately decided it would need gunner bars and a much shorter crank to get my elbows off my hips and out of the wind to find another free 10-15 watts

 

[ed72]

Maybe I am wrong but I did actually run a few CFD analysis runs of a rotating disk wheel at 30 mph with appropriate surface roughness and both laminar and turbulent effects. I only modelled head-on air flow and any trailing flow I saw was turbulent. I think when we are hit with a strong cross flow then a similarly strong and large eddy formation takes place on the downwind side. The turbulence is there all the time because the tire and leading surfaces of our bikes are anything but smooth with spokes, feet, cranks, dirt, all flailing in the leading smooth air. This eddy formation (vortex shedding) is most severe at the top of the (front) wheel and so has the effect of pushing us over more than steering us off course. We then have to countersteer to get the wheels back under us and before we know it we have moved over three or so feet. That is why I focus on a "locked" arm position and quick small reactions when in a narrow bike lane next to lots of traffic with strong crosswind conditions.

I dunno. It is complicated. I bought my first aero wheels 25 years ago, Specialized TriSpokes by Dupont and did read their research and others like Enve and HED patents over the years. I have gotten inconsistent results. I have read conflicting studies/stories. This is not my field, so, I probably am wrong. The best advice I have gotten was from Dean Philips at Ftiwercx who was fitting me for an upright TT long distance bike. He said he tests using Chung method but with small incremental improvements, he has to prove it on the road over many rides. Since he was Masters National TT champion, that tip stayed with me. This approach has worked for me although it is slow (Chung followed by real world testing). Then, I listen to foul mouthed and often very funny Hambini, the aeronautics engineer beloved over at Slowtwitch. He basically says the air is so messy and turbulent that static, steady state wind tunnel data is nearly rubbish. At some speed and yaw combination, the rim/tire interface or fancy mold marks (GP4000) do not matter because the pressure differential across the rim rises suddenly as the wind stalls the airfoil rim. What is clear is that 22 or 23 mm tires flush to the front rim is essential at V20 or other highspeed recumbent territory. A puffy tire could cost an additional 30-50 watts at 30 mph. If the tire is narrower than the rim, the airflow will reattach. If the tire is wider than the rim, this is a bad combination for riding fast or for having good steering control in blustery conditions. I believe my error is using the word laminar to describe the reattached airflow for optimized tire/rim interfaced wheels. I know this is important concept but my technical understanding is incomplete. On my endurance upright TT bike (Cervelo S3), I chased a 5-6 minute slightly downhill KOM. I could not get it......until I found the right tire/rim combination and optimal pressure....it was a 22 mm Conti Supersonic to an older Zipp rim with latex tubes at 80 psi IIR, I could not make my Flo60 carbon as fast with any tire or pressure. I smashed it on less power. Since Hambini slams Flo, I tend to appreciate his perspective especially since he calls himself a jerk. My two spoke is remarkbly faster in crosswinds than the Flo. Oh...I have not been able to beat my upright KOM even on a recumbent, which has taken me a lot of calories to figure out why.

This separation is why the gap between the frame and front wheel is often closed up with what some call a splitter. Besides the front wheel, this space under the seat and off the back of the bent is probably the second critical area that can be optimized. You can see these efforts below. My limited testing showed benefits



https://blog.silca.cc/part-5-tire-pressure-and-aerodynamics

https://www.hambini.com/testing-to-find-the-fastest-bicycle-wheels/

 

[M.J]

I'd be curious to know if the little splitters in front of and behind the wheels make much difference.

 

[Robert Holler]

I will put forth my belief that - for a STOCK bike that anyone can easily buy that does not need a ton of "special mods" - the V20 is THE fastest recumbent on the market.

 

[LarryOz]

I'd be curious to know if the little splitters in front of and behind the wheels make much difference.

In my testing the splitters do make a "little" difference. I do not have any numbers in front of me, sorry
But, Usually the higher the speed the more the difference.
i.e For the bike shown here: at 15mph you probably would not have any difference, 20mph - you might have a few seconds over the course of 10minuts. at 25mph you might have 3x the difference than at 20mph.
I think I averaged pretty close to 27mph for most of the 4 hours I rode that bike, so all those little seconds add up.
It is still not a ton of time! - but when you are trying to set a world record, ever little thing helps!

 

[TransAm]

This matches my testing results of a steeper seat angle allowing the rider to produce more power.

Are you sure it's the seat angle and not the hip angle that lets you make more power?

I just went from stock M to L chain stays on my V20, and it felt like I could make more power on hills. I only did a short test ride, so just initial impressions. But the L chain stays raised the cranks, which closed my hip angle slightly. I didn't change the seat back angle, but changing the back angle without moving the cranks would similarly close the hip angle.

 

[Bill Wightman]

I will put forth my belief that - for a STOCK bike that anyone can easily buy that does not need a ton of "special mods" - the V20 is THE fastest recumbent on the market.

Absolutely, but some of us just can't help but play with the ideas that come into our heads. Speaking of heads...I just placed a simple large radius bent 1/2 mm thick sheet of carbon fiber with slight taper aft at a steep pitch angle behind my helmet. It makes a big difference riding over 20 mph in quiet winds (and any headwinds), not so much in messy strong crosswinds. I had done a zero yaw CFD model at 25 mph and it was significantly better than a simple head/helmet model without it. It has to cover a little more than the bottom half of the helmet and slopes down as shown about 30 degrees. The head/helmet has a clearance to it of about 1/2" and helmet is free to move about without contact. I think it is also cleaning up some of the turbulence off my neck and upper shoulder region. It does not add any benefit if it is not high enough behind the helmet or is not sloped down. Also it weighs only 3.8 oz and I can put my drink tube/mouthpiece into it out of the breeze. My cat thinks the Ventisit cover is an awesome scratching post.

 

[paco1961]

Where did you obtain your sheet carbon. Wanting to play w something similar