V20C - Prototype

[vosadrian]

It would be great to do a back to back test of V20 vs V20C, but unless you have everything else identical, you would not know if any differences were from the new frame, or the other components. We know that wheels can make several mph difference in speed.

My personal opinion is that most of the aero advantage of the V20 is the position of the body. If the V20C has the same body position, then the aero effect in the front triangle would be minimal and probably not detectable. Also the V20 front triangle is very stiff. Much stiffer than a typical DF bike and typically stiffness is not a big deal except at very high power levels anyway (sprint powers at >500W). At more normal V20 powers of around 150-250W, the stiffness is unlikely to be a factor.

I think the V20C is certainly unlikely to be worse than V20, and may have some marginal aero improvements that may reduce power requirements by very small amounts. I think the main benefits of the V20C would be when climbing/sprinting due to weight/stiffness, and even then likely to be marginal. Its not like the old V20 was not stiff, and the weight differences are small % of total system weight of bike+rider (15kg bike + 65kg rider = 80kg. So a 500g weight saving is just over half a %)

But is sure does look nice in the photos above!!

 

[cruzKurt]

...... We know that wheels can make several mph difference in speed.

What sort of wheels can make that kind of difference? I mean, what aspects of a wheel make it faster. I have a stock 2019 v20, are there any budget options to increase speed via wheels?

 

[benphyr]

What sort of wheels can make that kind of difference? budget options to increase speed via wheels?

I fear that the budget options are increase, large, and astronomical... As in “increase the budget” to speed via wheels.

 

[Frito Bandito]

@cruzKurt
The Flamingeyeball on Youtube has a tutorial on Monokoting a wheel to make it a disc wheel for the back of your V20. I Monokoted my 80mm deep Campagnolo Bullet and while I did a pretty ugly job of it, it still likely works better than what I was using before.

I believe that Youtuber Marco Ruga also made a disc wheel with something similar, but I couldn't find it in my search a moment ago. You'll get the idea with the Flamingeyeball's video though.

As for the front wheel, some have had good results with a disc wheel as well when it isn't windy, but with sidewinds you might find yourself in the path of something petrol fueled. I have a 50mm deep Campagono Bullet on my front now, which is okay but not known in any circles as being a frontrunner in fast wheels. I've got my eyes peeled for a HED Jet 9 rim brake because at about 180lbs I am probably heavy enough that the 90mm deep wheel won't blow me off track too much.

 

[vosadrian]

What sort of wheels can make that kind of difference? I mean, what aspects of a wheel make it faster. I have a stock 2019 v20, are there any budget options to increase speed via wheels?

What makes a fast set of wheels? A deeper more aerodynamic rim profile. Less and bladed spokes. Nice rolling and aero hubs. Good fast tyres well matched to the aero profile of the rims.

I run these wheels at US$750 (25mm wide version with Sapim spokes and Novatec hubs): https://www.yoeleobike.com/products/carbon-bicycle-wheels-sat-c88-road-std

If you couple these wheels with some fast tubeless tyres (I run GP5000-TL 25mm), compared to the stock V20 wheel/tyres, at the same effort to go 25mph on the stock wheels/tyres, you are likely to go 27-28mph.

Like others have mentioned here, I have also covered the rear wheel previously, but I did not really notice a big difference over the already very fast wheels without covers. For me I would cover the wheel for a race in light wind, but for normal riding I use it uncovered which is less susceptible to being blown about by wind, and also much easier to access the valve to top up the tyre pressures!!

 

[jond]

Larry 32 mm tyres at 50 psi are very very comfy. I run them on the pelso. Chunky as.

 

[DavidCH]

Something tells me Larry will be delivering some interesting facts and figures pretty soon

 

[Apollo]

OK - My FLO77 tubeless rims came today. I also have a pair of Pro One 32 tubeless tires. After about 2 hours of work I get them all mounted and installed on the V20c. I definitely like the look of the wide rims. The V20c is starting to look faster everyday! haha
View attachment 13373

Here are some shots of the wheels. Wow - the 32mm tires are really large when compared to my 22mm I have a this other wheel!
The 32mm makes the wheel another 1" taller that a 22mm. When I compared my existing FLO90 with a 28mm tires the difference was still 1/2" in height. Here are some pics of the wheels to see what I mean.

View attachment 13376View attachment 13375View attachment 13374

I rode around the block a couple of times. Can't really tell a huge difference from what I am used to - Mostly 28mm - I'll have to dial the pressure down once there are full sealed then it might seem more comfy. Max PSI is 70 for the 32 which seems pretty low. The do hold a lot more air that is for sure!

Hi Larry,
Are you sure the 32mm width is really worth it? I could see justification going from a narrow tire to say 28mm but over 30 seems like a performance downgrade to me. Extra weight and aero drag. The max pressure is too low unless you're searching for comfort above all else. The consensus on TT forums seems to hover around the mid-20mm for an overall best performing tire. I guess when it comes to recumbents even tire width could be a very different matter. Do you ride mostly bumpy roads? Curious as to why such a wide tire.

 

[cruzKurt]

Hi Larry,
Are you sure the 32mm width is really worth it? I could see justification going from a narrow tire to say 28mm but over 30 seems like a performance downgrade to me. Extra weight and aero drag. The max pressure is too low unless you're searching for comfort above all else. The consensus on TT forums seems to hover around the mid-20mm for an overall best performing tire. I guess when it comes to recumbents even tire width could be a very different matter. Do you ride mostly bumpy roads? Curious as to why such a wide tire.

I was told 28mm is the widest that would fit on my v20, I guess that changes with the v20c? Bike looks great Larry.

 

[LarryOz]

I’d be interested in any wind tunnel tests. The ovalized boom/slider with integrated clamp and new fork look like there’ll be some aerodynamic advantage.

Well, I do that as soon as I get my windtunnel built!

 

[M.J]

I was told 28mm is the widest that would fit on my v20, I guess that changes with the v20c? Bike looks great Larry.

That's correct, the V20c will fit wider tires.

 

[LarryOz]

Hi Larry,
Are you sure the 32mm width is really worth it? I could see justification going from a narrow tire to say 28mm but over 30 seems like a performance downgrade to me. Extra weight and aero drag. The max pressure is too low unless you're searching for comfort above all else. The consensus on TT forums seems to hover around the mid-20mm for an overall best performing tire. I guess when it comes to recumbents even tire width could be a very different matter. Do you ride mostly bumpy roads? Curious as to why such a wide tire.

I just wanted to try something different. It is my gut feeling that 30-32mm tires will end up yielding a better and faster ride on relative rough roads and stuff like chip-seal. I did just recently ride this V20c prototype on an outdoor track with very smooth surface and was able to ride 25mph on about 3.1 W/Kg. This is relatively close to what I was able to get on my V20 with 25mm front and 28mm rear on rougher roads. However I did not bring the V20 to the track with those smaller tires to test it straight up against the V20c. I think that the smaller tires would probably be faster on the smooth track regardless is they were on the V20 or V20c.
Of course this does not mean the V20c is slower than the V20 - it just means the 32mm tires at 50-60 psi are slower than the 25mm at 80-90psi on a very smooth road. I'll have to just swap wheels and tires around on the V20c different road surfaces to complete the testing.
Unfortunately I can't really try the old V20 with the new wide wheels and tires. One because they will not fit on the frame and 2 because the V20 will no accept the thru hub format - and of course the V20c will not accept the old skewer format wheel either. So it will be hard to do an apples to apples testing.
I agree with most of what has been said above about the deltas between exactly built V20 and V20c - If they are both setup exactly the same I doubt there would be any real difference in speed. There will probably be better reaction to sprinting and a better feel for climbing and carving turns in the V20c due to the stiffness afforded by the CF and thru hub wheels.

 

[vosadrian]

I believe ride quality and rolling resistance on rough surfaces is mostly about the tyre pressure and less to do with the tyre width. But the width comes into play because the risk of bottoming the rim out on a bump is higher with a narrow tyre than a wider (taller) tyre. So basically you run bigger tyres when you run lower pressures to reduce the chance of a tyre or wheel failure when running low pressures. But the rolling resistance of a wider tyre should be similar to a narrower tyre at the same pressure.

@LarryOz , did you ever test the effect of tyre pressure on W/kg with the V20 with 25mm tyres? It is probably very dependant on road surface quality. I guess Pro level TT bikes have whatever technoclogy is likely to be the best at the moment. They should have tested all this stuff out. I thought many of them are running tubeless 25mm (Continental recently released a tubeless tyre specifically designed for TT and it only comes in 25mm), but I don't know what pressure they are running. Most pro TTs are done on normal surface roads.... rarely on specifically smooth surfaces.

I believe I am heavier than Larry, and I run my 25mm tyres down to around 60psi at times (I pump up to 80psi, but not every ride, so sometimes I have ridden with down to 60psi). I have not noticed any ill effects of running 60-70psi on my 25s. The ride is nice at 60psi, but it is not terrible at 80psi. I used to run 110psi in tubed 23mm tyres years ago, and it is much better than that!!

 

[LarryOz]

@LarryOz , did you ever test the effect of tire pressure on W/kg with the V20 with 25mm tires? It is probably very dependent on road surface quality. I guess Pro level TT bikes have whatever technology is likely to be the best at the moment. They should have tested all this stuff out. I thought many of them are running tubeless 25mm (Continental recently released a tubeless tyre specifically designed for TT and it only comes in 25mm), but I don't know what pressure they are running. Most pro TTs are done on normal surface roads.... rarely on specifically smooth surfaces.

I have not - but I generally run 80-90 psi on my 25 tubeless - if I ever have a bunch I time it would a cool experiment to test different pressures, but my gut is telling me that it would not be very much difference until the pressure was lower than 50 - and you probably would not want to ride on normal roads with that. Yes, and I am sure if you dig enough you will find testing by pro teams and manufac. that would should the different rolling resistance of different psi.

 

[vosadrian]

I reckon the difference in rolling resistance between 32mm tyre at 60psi and 25mm tyre at 80psi would be minor, and on chip-seal would be negligable with a comfort advantage to the 32mm/60psi.

What I am interested in is whether the aero penalty of the wider wheel/tyre will be much. There is no getting around the fact that a smaller version of the same profile (lower frontal area) will have less aero drag. The profile sets the Cd, and then you multiply the Cd by A for the total drag and A is larger with wider tyres. When you go wider, you have to also go deeper to maintain the same shape to get the same Cd. So in theory if the width is increased to maintain the same Cd, you need to have a deeper wheel (to have the same scaled aero profile in both dimensions). My guess is that Cd will be a little worse when going wider at the same depth and A will also be higher due to wider tyres. Therefore CdA will be worse. How much worse as a factor of the entire bike and rider CdA? Probably not much. The ideal wheel/tyre for aero is as narrow as possible and deep as possible. That is not practical, so compromises have to be made. 25mm seems to be the current ideal as it allows enough volume to get down to the lower pressures required for efficiency on chip-seal while still have enough height to protect from most road hazards that would damage a wheel/tyre that was 10mm high. Also it support the typical contact patch size required at these lower pressures.

Another factor on bents is that the wheels/tyres are in the shadow of the body position of the rider more, so much of the air disturbed by the wheel/tyre is either before or after being disturbed by the rider (top half of rear wheel in shadow of rider, and top half of front wheel shadows frame/rider). So the the disturbed air from the more forward object may reduce drag on the following object to have a combined CdA figure that may not be as bad as expected for the wheel alone.

 

[Don1]

My brain hurts

 

[DavidCH]

I guess thats why magic is magic

 

[vosadrian]

Sorry guys. I'm an engineer and I love nerding out on the physics of bicycles. I need to mind my language!

 

[Don1]

The interesting talking point is when aero gets better ,ie Larry.... rolling resistance becomes larger percentage than "normal".

 

[Dryday]

Any more news about this, was an official record set?