"Recumbent" qualification in "world's fastest bike" claim for the V20

[Enid]

Why was the word "recumbent" inserted before the fastest bike claim throughout? Is it that there are some TT bikes with a lower CdA?

I would think that the claim that the V20 is the world's fastest recumbent bike is a higher bar than the world's fastest road bike. The M5 carbon high racer can be made to have a lower CdA as well as lower or similar weight, so it would come down to stiffness, right? It is difficult to surpass the CdA of an M5 and still be road-ready.

 

[Beano]

Cruzbike at the A2 Wind Tunnel

February 6, 2017/ Jim Parker After ten years of making bicycles, we decided to test our fastest model, the Cruzbike V20 performance recumbent bike, in a high-tech wind tunnel in one of the USA’s motorsport hubs, Charlotte, North Carolina. Cruzbike designer Jacob Bouchard flew in from Brooklyn...

cruzbike.com

Cda of .201 with velocity wheels, which are run off the mill wheels with no deep section rim.
.158 with full disk wheels.

Dan's UCI Hour Record

UCI HOUR RECORD 46.690km. This was the distance Dan rode back in 2014 at Palmer velodrome in Reading. I’m not even sure he knew that that day would mark the beginning of an eight year relentless pursuit of the UCI World Hour Record. This blog post is not a deep dive into the data, nor a...

www.shopforwatts.co.uk

UCI hour record holder, Dan Bingham got his Cda to as low as .140 for his hour record. Every bit was made to get his Cda as low as possible. His position, bike, temp of the velodrome and at altitude. He worked with Ineos in order to get his Cda as low as possible. Many think this is a dry run for when Ganna attempts the hour record in a few weeks.

What's your cda of the M5? Trouble finding a source online which is tested.

 

[Enid]

Cruzbike at the A2 Wind Tunnel

February 6, 2017/ Jim Parker After ten years of making bicycles, we decided to test our fastest model, the Cruzbike V20 performance recumbent bike, in a high-tech wind tunnel in one of the USA’s motorsport hubs, Charlotte, North Carolina. Cruzbike designer Jacob Bouchard flew in from Brooklyn...

cruzbike.com

Cda of .201 with velocity wheels, which are run off the mill wheels with no deep section rim.
.158 with full disk wheels.

Dan's UCI Hour Record

UCI HOUR RECORD 46.690km. This was the distance Dan rode back in 2014 at Palmer velodrome in Reading. I’m not even sure he knew that that day would mark the beginning of an eight year relentless pursuit of the UCI World Hour Record. This blog post is not a deep dive into the data, nor a...

www.shopforwatts.co.uk

UCI hour record holder, Dan Bingham got his Cda to as low as .140 for his hour record. Every bit was made to get his Cda as low as possible. His position, bike, temp of the velodrome and at altitude. He worked with Ineos in order to get his Cda as low as possible. Many think this is a dry run for when Ganna attempts the hour record in a few weeks.

What's your cda of the M5? Trouble finding a source online which is tested.

0.14 is very low! So why qualify with the word “recumbent” before “world’s fastest bike?” I’m not seeing practical DF bikes with a CdA that low.

 

[Enid]

0.14 is very low! So why qualify with the word “recumbent” before “world’s fastest bike?” I’m not seeing practical DF bikes with a CdA that low.

*By practical I mean one that can be ridden on the street and qualify for the get your money back program at Cruzbike.

 

[Enid]

There are a lot of calculated values for the CHR, all with big riders on them. No wind tunnel tests that I am aware of. But the aching method is at least a data point. 0.15-0.195.

The Recumbent Bicycle and Human Powered Vehicle Information Center

Recumbent and Human Powered Vehicle Information Center

recumbents.com

 

[Henri]

Why? Because every exclusion makes the statement a bit safer!
I could immagine that someone would attack the statement, saying that uphill an upright roadbike has an advantage.
Maybe it's because they (legally) base the statement on records, that are held in very specific disciplines.

But that's just boring legal stuff and any advertising claim should just be ignored anyway.

 

[LarryOz]

Why was the word "recumbent" inserted before the fastest bike claim throughout? Is it that there are some TT bikes with a lower CdA?

I would think that the claim that the V20 is the world's fastest recumbent bike is a higher bar than the world's fastest road bike. The M5 carbon high racer can be made to have a lower CdA as well as lower or similar weight, so it would come down to stiffness, right? It is difficult to surpass the CdA of an M5 and still be road-ready.

It is easy to probably claim one bike is more aero than another - put then both in a wind tunnel. But those results would not be very useful.
We must remember that the real value that everyone is really after is "their CdA" on a specific bike". And the body makes up more than 50% of this value. I dare say it may be closer to 75%.
Therefore this becomes a "very individual" element. You can put two people on the same bike and get very different CdA values.
Then you can put those same 2 people on a totally different bike and then one that was better on the previous bike may be worse on the 2nd bike.
Example:
I fit into the V20 like a glove since I am about 5'7". I have a very low CdA on this bike.
My friend who is 6'1" and weights about the same as me cannot go nearly as fast as me because he sits higher on the bike due to his longer frame.
I had an M5 CHR - I tricked it out pretty much as much as I could (just like my V20) - and my power to speed ratios were pretty much exactly the same. I'd rather ride and race the V20 over the M5 because I did not like dealing with the chain and heal strike on on the front wheel of the M5 and preferred the FWD MMB platform.

There are so many variable in determining CdA. IMHO the values should not really even be used to compare bikes against each other.
The real benefit to me is to have a number I can use with a certain build of a certain bike I am on - then when I change something I can see if it is making me faster or slower. That is how I use the number.

 

[Frito Bandito]

Spot on Larry! I am 5'10 and my head sticks up a bit in my current position on the V20 so I might be able to let the headrest out a bit, but then I have air hitting my neck and the bottom of my chin, showing how each of us just have to fine tune our own position to get the CdA down on whichever bike we ride. I'll stick with the V20 for the same reasons you listed, plus a couple of more.

 

[Andrew Wilson]

Another who concurs.... I keep chasing Larry's power to speed ratio but at 6ft....it's a loss cause

 

[vosadrian]

Is there any formula to determine this power to speed ratio?I wonder if it is a graph of the same shape for everyone but different scalers that we can fit a curve to and have some number that defines your curve. Then again that would probably just be CdA!!

@LarryOz , what is you power on the V20/V20C at 25mph? I think you are pretty low around 160W? I think I am around 180W. Still a little more work to do for me!

 

[LarryOz]

@LarryOz , what is you power on the V20/V20C at 25mph? I think you are pretty low around 160W? I think I am around 180W. Still a little more work to do for me!

Nope - I am not able do 25 mph on 160 watts! I am about 180 watts for 25 mph on perfect flat course - so if you are that too - we are pretty close. When I first set the 100 mile road attempt (about 7 years ago) I was needing about 200 watts for 25 mph - so I have figured out how to be more aero.

However - It is really better to not just talk about power only though. We should really be talking about Wt/Kg - because 200 watts for a 200 lb person is much different than 200 watts for a 150 lbs person.

For me at 150 lbs = 68kg. so 180/68 = 2.65 Wt/Kg - This equates to a very low CdA. I use myWindsock to give me an estimated CdA. It appears to be fairly accurate. I am around 1.25-1.30 most of the time on my V20 with my best setup for speed

 

[vosadrian]

I agree with all you say Larry. I am a similar size to you being just an inch taller and a few kg heavier. I found on an outdoor velodrome I did (on a moderately windy day) about 10 minutes at 40kph (25mph) and average power was 180W. That was a good road surface, so probably a little worse on normal roads. I use MyWindSock also. I get a fair bit of variation depending on the loop as my road surfaces and the traffic towing me along varies a lot. My CdA seems to be in the 0.15-0.2 range. I think in reality I am around 0.17, and that equates well on a CdA calculator as 180W at 0.17 CdA is around 40kph (25mph).

My problem is that I don't think I am as well adapted to bent riding as some. I can put out good power on my DF. At peak fitness I can get my FTP to around 300W. I can't get near that on the bent, and can only get to around 250W FTP. But for me on the V20, a ride at >200W average power is a pretty big effort, but it feels like a fairly easy effort on the DF. At least that 200W gets some serious speed!!

 

[Frito Bandito]

Same here Adrian. My FTP was about 250w on my DF, but my FTP on my V20 is about 215-220w. According to MWS my CdA is always between 0.195 and 0.205. I've tried several seat bags, setups, DIY tail boxes and others, but the lowest I ever got to was about 0.185. That leaves me at about 39.2kph on a flat course

 

[vosadrian]

I'm not sure why some riders can dip down towards 0.15 CdA and other are closer to 0.2 on the V20. I guess part of it is the body shape and size. Not sure how much of the bike features effect that (like bars and position etc.). My bike is pretty similar to Larry's with low drop bars and similar wheels and a tail box. This is no coincidence! Easiest way to get fast is to copy the fast guy!

 

[Frito Bandito]

Yep, I try to do the same. No need to reinvent the wheel. I think in my case it is my head sticking up too much, my helmet shape being a bit too bulbous on the top front, my lense being pretty vertical, none of the bags or other stuff behind the head has been great, the brifters sitting up too high, and the head rest bars hanging out of the bottom almost 2", and probably the lenses do no cover the earhole gap well enough. Those are a start for sure, but another thing is that I have pretty wide shoulders. Unless I get one of those massive tailboxes that we see on lowracers to clean up my wake then I am just going to have to accept it.

 

[M.J]

I'm not the data enthusiast that many of you are, but I'll chime in. The chart below is from a ride I did last week. The highlighted part is a 25 mile out and back, as flat as is possible here, on pavement that was ok but not great. Covered rear wheel, 50mm deep front wheel with bladed spokes, aftermarket seat, large chainstay. The seat to BB rise is +11" , similar to a CHR. Bullhorn bars with stock brifters for straight arms and tucked in elbows. Rider is 5'11, 165lb.
25.9mph on 213w, including the little spike to get back up to speed at the turnaround. If I took that out then it would likely be a little faster at slightly fewer watts. I suppose you could do this on a Dan Bingham style TT bike in full skin suit and all that, but in the real world you're unlikely to meet another rider doing more speed on fewer watts than you on your V20.