Test riding a true racing recumbent

[ed72]

I like what View-Speed offers for Aero Shoe Modification. It's probably more significant for recumbent riders than for up-right riders. I wonder how much weight it adds and if that would negatively impact your time compared to any aero advantage.

Aero almost always outweighs weight unless it is an uphill TT. Weight, power, speed is linear whereas aerodynamics is cubic. At 30 mph, the incremental linear factors are fairly trivial. For instance, at 30 mph, total power for me is around 280 watts of which 220 is the wind and 60 is friction (mostly road). Increasing the weight by 1 pound is about 0.5% and about 0.3 watts additional resistance due to the weight. Lowering the CdA by 0.005 would drop the required power by 7 watts, approximately. Numbers just to illustrate. On Osiris' bike, the effect might be even larger especially with small cranks. The hour record on a recumbent was set with 130 mm cranks....for a reason. An extra pound could be an easy tradeoff.

The aero shoe mod could be done DIY. I have to walk alot as a randonneur and don't want to bugger up my shoes.

 

[McWheels]

It seems to me that the rider's feet would be a major source of aerodynamic drag on a recumbent. It would be tempting to design some conical shaped foot enclosures, so that the air would pass smoothly around them.

I've been wondering that for years. I had mostly imagined it'd be a trianlge shaped thing on the underside (front side) of the pedal. Keep going like that and you'll end up with a Wintr fairing...

 

[Balor]

More like F40 nosecone

 

[ed72]

Arrowhead. 10 miles under 19 minutes by Larry Oz. 31.8 mph in what looks like 245-255 watts average if his power meter is right, I was just eyeballing it lap after lap. He would drop down to 220-230 on the easy, fast section and then back up to 260-280 watts on the slow section. CdA has to be super low....maybe 0.120 to 0.125 m2. For perspective, this bike and rider at 25 mph would only require 130-145 watts depending on road surface, tires, and weather. Pretty amazing performance.

 

[bladderhead]

It seems to me that the rider's feet would be a major source of aerodynamic drag on a recumbent. It would be tempting to design some conical shaped foot enclosures, so that the air would pass smoothly around them.

I have mid-foot placement and heel-clips so my feet stick up above the pedals. Now I know why I am so slow.

 

[Osiris]

Arrowhead. 10 miles under 19 minutes by Larry Oz. 31.8 mph in what looks like 245-255 watts average if his power meter is right, I was just eyeballing it lap after lap. He would drop down to 220-230 on the easy, fast section and then back up to 260-280 watts on the slow section. CdA has to be super low....maybe 0.120 to 0.125 m2. For perspective, this bike and rider at 25 mph would only require 130-145 watts depending on road surface, tires, and weather. Pretty amazing performance.

A while back, Larry sent me his test data for various bents in a spreadsheet format. Here's what he has for his Arrowhead.

Equipped with 150 mm cranks, Rolf TT-85 tubular rear, 650 front with 80mm fairing:

200W = 25.1 mph
219W = 27.5 mph
257W = 28.9 mph
300W = 30.7 mph

Equipped with a full disk rear wheel and tubeless tire (he doesn't say what), 650 front with 80 mm fairing:

289W = 33 mph
260W = 31.5 mph
267W = 31.8 mph

The last three tests were performed at Charlotte Motor Speedway. He doesn't say where the previous four came from.

 

[ed72]

Interesting numbers. Differences are not explained by just wheel or tire. Nonetheless, fast as all get out. Wow.

I am chum.

119 watts gets my 220 lb carcass to 22.1 mph on a warm, humid day.

 

[Osiris]

Interesting numbers. Differences are not explained by just wheel or tire. Nonetheless, fast as all get out. Wow.

I am chum.

119 watts gets my 220 lb carcass to 22.1 mph on a warm, humid day.

Larry's numbers have always puzzled me. With one minor exception, they don't come even close to what I'm seeing on the same bents (M1, M5, and V20). I'm seeing differences of as much as 50 watts at the same speeds, and he and I both use Garmin Vector power meters. Now, it's true that Larry is much shorter than I am, that he's done quite a bit of equipment tweaking, and that his tubular racing tires are no doubt faster than my GP4000's, but the difference is still difficult to explain. Even comparing his own numbers above, you can see that in one case he was averaging 267W to go 31.8 mph, while in another he was averaging 300W to go only 30.7 mph. That's a whopping difference. The only equipment change he mentions in his notes is that the 267W/31.8 mph figure was achieved with a full disk rear wheel. Can a disk really make such a dramatic difference? I saw no such improvement when I put one on my CA2 and M5.

 

[ed72]

differences in wheel and tires from an aero perspective can be 30-50 watts at 31 mph but not usually. At 20 mph, the wheel tire differences would not be noticeable (5-8 watts or something like that). Just an undetectable 2-4 mph breeze can make a difference. When I test, I always use the same kit and only change one variable at a time and then correct for temperature, pressure, and humidity. I test on out and back pipe using chung or I also do 10 miles in one direction and 10 miles in the other in calm conditions at constant speed and average the results, I do this in order to get training while testing. If I do chung testing, I lose training. My guess why Larry's numbers seem far apart? The wheel added half and clothing or environmental conditions added the rest. Not surprising. I see large differences just in kit choice and also temperature/humidity because air density is not an inconsequential factor. That is why some hour attempts are not only at altitude but they heat the velodrome.

Hambini trashes Flo.

https://www.hambini.com/blog/post/bicycle-wheel-aerodynamics-which-one-is-fastest/

 

[Osiris]

differences in wheel and tires from an aero perspective can be 30-50 watts at 31 mph but not usually. At 20 mph, the wheel tire differences would not be noticeable (5-8 watts or something like that). Just an undetectable 2-4 mph breeze can make a difference. When I test, I always use the same kit and only change one variable at a time and then correct for temperature, pressure, and humidity. I test on out and back pipe using chung or I also do 10 miles in one direction and 10 miles in the other in calm conditions at constant speed and average the results, I do this in order to get training while testing. If I do chung testing, I lose training. My guess why Larry's numbers seem far apart? The wheel added half and clothing or environmental conditions added the rest. Not surprising. I see large differences just in kit choice and also temperature/humidity because air density is not an inconsequential factor. That is why some hour attempts are not only at altitude but they heat the velodrome.

Hambini trashes Flo.

https://www.hambini.com/blog/post/bicycle-wheel-aerodynamics-which-one-is-fastest/

Very disappointing to read that about Flo, especially since I have two of their wheels.

Once my skin suit arrives, I'll be doing some serious speed testing on my new favorite trail. Hopefully the high winds we're currently experiencing will have disappeared by then.

 

[ed72]

I have many Flo wheels.

Flo 60 carbon tested just a little slower than my 2-Spoke in calm conditions. I am not sure what to think of Hambini's results.

I bought a 2-spoke trying to gain cross wind stability and the new wheel helped and is clearly faster in cross winds than the flo60 on the front. I also found poor airflow under and around the seat was a bigger problem for me. I modified with 4 inch wide and thick electrical tape. Trucks going by me at 60 mph plus no longer suck me in (as much). Hoping my Polk seat is finished soon and helps even more.

 

[Osiris]

I have many Flo wheels.

Flo 60 carbon tested just a little slower than my 2-Spoke in calm conditions. I am not sure what to think of Hambini's results.

I bought a 2-spoke trying to gain cross wind stability and the new wheel helped and is clearly faster in cross winds than the flo60 on the front. I also found poor airflow under and around the seat was a bigger problem for me. I modified with 4 inch wide and thick electrical tape. Trucks going by me at 60 mph plus no longer suck me in (as much). Hoping my Polk seat is finished soon and helps even more.

Is Kent installing the seat for you? I didn't think it was necessary, but when he started work on my M5, we discovered all sorts of "factory flaws" that had to be corrected. He wound up having to drill out the existing screw holes entirely, as they had been misaligned. In the end, what I had thought would be a 15 minute process took up the entire morning.

I think you'll be quite happy with the Railgun, especially considering the long distance rides you do. My longest ride on it so far was 6.5 hours. That's about three times longer than my regular rides, and I didn't even have to stop for a break. It's that comfortable. Aerodynamically, I think you'll see a big improvement. My max power dropped significantly, as seems to be the case whenever I change my posture on a recumbent, but I nevertheless was able to sustain faster speeds than ever before. You will need a new tiller though, because the stock one will be at the wrong angle. I purchased one that could be adjusted for different angles, which proved to be ideal.

 

[ed72]

He had hoped to have it ready but some delays. I was down there a few weeks ago. Hoped to have it for Sebring but my training has been lousy due to some health issues, so, the race and seat are rather moot. I might give Sebring a whirl February 9-10 nonetheless as a training ride and then do a 400k in southern FL Feb 16. Kent indicated that riders get more power using his seat. He did say he preferred to install it. I can't agree to drilling out the mount-it does come off. I would probably swap back to my Thor and m5 tailbox if I took it touring.

I'd love to have a Mircigleo with a BB lowered a bit with that fairing-like boom over the front wheel-this is one secret to its speed.

 

[Balor]

Larry's numbers have always puzzled me. With one minor exception, they don't come even close to what I'm seeing on the same bents (M1, M5, and V20). I'm seeing differences of as much as 50 watts at the same speeds, and he and I both use Garmin Vector power meters. Now, it's true that Larry is much shorter than I am, that he's done quite a bit of equipment tweaking, and that his tubular racing tires are no doubt faster than my GP4000's, but the difference is still difficult to explain.

Factors you describe can (and do) explain why he is faster. He not also not a real powerhouse - despite his w/kg being pretty good, which is absolutely normal as well.

So, unless you are willing to do surgery by removing your body bits not nessesary to your cycling, you'll have to make up with higher power I presume .

 

[ed72]

FWI....my numbers are similar to Larry's first set but his second blows mine out of the water. If I took my front light off and put the skinsuit on, I suspect they would be very, very close.

 

[Osiris]

FWI....my numbers are similar to Larry's first set but his second blows mine out of the water. If I took my front light off and put the skinsuit on, I suspect they would be very, very close.

Here are some numbers from his Arrowhead tests. All of these were performed at Carrier Park circle. I assume the tests in each group were performed on the same day, but I'm not sure:

20.77 mph @ 100 watts
19.94 mph @ 100 watts
20.31 mph @ 101 watts

22.18 mph @ 125 watts
22.24 mph @ 125 watts
22.64 mph @ @126 watts

23.84 mph @ 150 watts
23.53 mph @ 150 watts
24.08 mph @ 150 watts

25.76 mph @ 175 watts

27.37 mph @ 200 watts

28.56 mph @ 225 watts

30.5 mph @ 276 watts

31.17 mph @ 296 watts

 

[ed72]

Here are some numbers from his Arrowhead tests. All of these were performed at Carrier Park circle. I assume the tests in each group were performed on the same day, but I'm not sure:

20.77 mph @ 100 watts
19.94 mph @ 100 watts
20.31 mph @ 101 watts

22.18 mph @ 125 watts
22.24 mph @ 125 watts
22.64 mph @ @126 watts

23.84 mph @ 150 watts
23.53 mph @ 150 watts
24.08 mph @ 150 watts

25.76 mph @ 175 watts

27.37 mph @ 200 watts

28.56 mph @ 225 watts

30.5 mph @ 276 watts

31.17 mph @ 296 watts

Remarkable.

This is the best I have done.....my other three best 10 mile TT (20:43-20:47) were within 4 seconds of each other.

29.1 mph 256 watts (10+ miles)

29.1 mph 269 watts (5 miles)

28.6 mph 249 watts (3 miles)

28.2 mph 232 watts (1 miles)

30.4 mph 260 watts (1 mile)

I guess I could ring John M. up and get me under 20 minutes. I am not going to get 10% more power to go 3% faster but there are some hills on this TT....3-5% more power, weight loss and some small aero tweaks might get me there.

 

[Osiris]

Remarkable.

This is the best I have done.....my other three best 10 mile TT (20:43-20:47) were within 4 seconds of each other.

29.1 mph 256 watts (10+ miles)

29.1 mph 269 watts (5 miles)

28.6 mph 249 watts (3 miles)

28.2 mph 232 watts (1 miles)

30.4 mph 260 watts (1 mile)

I guess I could ring John M. up and get me under 20 minutes. I am not going to get 10% more power to go 3% faster but there are some hills on this TT....3-5% more power, weight loss and some small aero tweaks might get me there.

Be prepared to pay a fortune for a new bent from John. He's not cheap, and he won't budge on price. His lightly used creations can be had for thousands less, but finding an M1 or Arrowhead for someone of your proportions might be a challenge.

It appears that my speed suit won't arrive until next Thursday at the earliest, but I'm going to take the M1 out for some speed/power testing this weekend regardless. If anything, it will be interesting to see how much of an improvement I'll get once I ditch the Gatorskin tire and rumpled jersey.

 

[ed72]

Be prepared to pay a fortune for a new bent from John. He's not cheap, and he won't budge on price. His lightly used creations can be had for thousands less, but finding an M1 or Arrowhead for someone of your proportions might be a challenge.

It appears that my speed suit won't arrive until next Thursday at the earliest, but I'm going to take the M1 out for some speed/power testing this weekend regardless. If anything, it will be interesting to see how much of an improvement I'll get once I ditch the Gatorskin tire and rumpled jersey.

$4400 for the frame if I remember.

I had inquired about having a MBB FWD like the V20 made but one that would use a tiller and little bars so that my arms could rest on my stomach keeping pressure off my cervical spine. The number was x percentage higher than M1 IIRC......in any case, it is worth it to someone with the money. I don't know if the M1 is the fastest ever but it has to be darned close and John can fashion a small tailbox to hold my randoneuring gillet, reflective straps, and a rain jacket.

 

[Osiris]

$4400 for the frame if I remember.

He quoted me $6000 for just the frame, and that was a couple of years ago. Add on the other components, and you get to $8000 pretty easily. If I had the potential to set world records, I might have seriously considered it, but it's a bit much for just an over the hill weekend rider.

I had inquired about having a MBB FWD like the V20 made but one that would use a tiller and little bars so that my arms could rest on my stomach keeping pressure off my cervical spine.

John did build one MBB FWD, at least as far back as 2011. I think it was called the Hammerhead:

I once e-mailed someone who was selling his, but I can't remember who it was. Anyway, he didn't seem terribly impressed with it's performance, so I lost interest.