Aero penalty of gravel bike

[bobinski]

Hi,
I am about to get a Vielo V+1, a pretty racey gravel bike with integrated cables , one piece bar and stem etc. Its not marketed as an aero bike as such but like i say it is at the racier end of the market. It will be my do it all bike. I will have 2 possibly 3 sets of wheels. A gravel set, alightweight 1300g climbing set for trips to the Alps say for road riding with 28/30mm tyres and perhaps also a set of deep rim wheels for faster riding.
The frame can accomodate 50mm tyres on 700c so i am wondering what the aero penalty might be , especially at the front, with either of the two road wheel options. There will be quite a gap between wheel and fork even with 32mm tyres. Cn anyone point me to some tests others have done? My google search skills have proved worthless.
Cheers

[romanmoser]

Aero penalty compared to what ?
An aero disc road bike ?
A round and oval rim brake bike ?

Your position legnth width wise will have more impact ....

[Monticola]

https://www.swissside.com/blogs/news/gr ... ?locale=en

[robeambro]

Hi,
I am about to get a Vielo V+1, a pretty racey gravel bike with integrated cables , one piece bar and stem etc. Its not marketed as an aero bike as such but like i say it is at the racier end of the market. It will be my do it all bike. I will have 2 possibly 3 sets of wheels. A gravel set, alightweight 1300g climbing set for trips to the Alps say for road riding with 28/30mm tyres and perhaps also a set of deep rim wheels for faster riding.
The frame can accomodate 50mm tyres on 700c so i am wondering what the aero penalty might be , especially at the front, with either of the two road wheel options. There will be quite a gap between wheel and fork even with 32mm tyres. Cn anyone point me to some tests others have done? My google search skills have proved worthless.
Cheers

I made a near-identical thread a few weeks back, you may want to look for it.

[bobinski]

https://www.swissside.com/blogs/news/gr ... ?locale=en

Thanks.
Interesting.
I wish they had tested with the Swiss Side HADRON2 Utimate 625, Continental GP5000
25mm tyre, on the gravel bike too which is the comparison i really want to see. I would hope the difference would drop markedly.

[bobinski]

Hi,
I am about to get a Vielo V+1, a pretty racey gravel bike with integrated cables , one piece bar and stem etc. Its not marketed as an aero bike as such but like i say it is at the racier end of the market. It will be my do it all bike. I will have 2 possibly 3 sets of wheels. A gravel set, alightweight 1300g climbing set for trips to the Alps say for road riding with 28/30mm tyres and perhaps also a set of deep rim wheels for faster riding.
The frame can accomodate 50mm tyres on 700c so i am wondering what the aero penalty might be , especially at the front, with either of the two road wheel options. There will be quite a gap between wheel and fork even with 32mm tyres. Cn anyone point me to some tests others have done? My google search skills have proved worthless.
Cheers

I made a near-identical thread a few weeks back, you may want to look for it.

I have looked and i cannot find it.

[robeambro]

Hi,
I am about to get a Vielo V+1, a pretty racey gravel bike with integrated cables , one piece bar and stem etc. Its not marketed as an aero bike as such but like i say it is at the racier end of the market. It will be my do it all bike. I will have 2 possibly 3 sets of wheels. A gravel set, alightweight 1300g climbing set for trips to the Alps say for road riding with 28/30mm tyres and perhaps also a set of deep rim wheels for faster riding.
The frame can accomodate 50mm tyres on 700c so i am wondering what the aero penalty might be , especially at the front, with either of the two road wheel options. There will be quite a gap between wheel and fork even with 32mm tyres. Cn anyone point me to some tests others have done? My google search skills have proved worthless.
Cheers

I made a near-identical thread a few weeks back, you may want to look for it.

I have looked and i cannot find it.

I'm sorry I thought I'd made a thread, I just commented here: viewtopic.php?f=3&t=154692&hilit=gravel ... 5#p1766065

Hope it helps.

[Magnetize6932]

The biggest aero penalty will come from the more upright position of the gravel bike. The stack on the G + 1 is 25-30mm higher compared to the Vielo R + 1 of the same size.

[TobinHatesYou]

The biggest aero penalty will come from the more upright position of the gravel bike. The stack on the G + 1 is 25-30mm higher compared to the Vielo R + 1 of the same size.

I considered sizing down in something like a BMC Kaius with its really long reach vs low stack for a second, but the Kaius fork is pretty chunky and lacking any aero profiling.

[bobinski]

The biggest aero penalty will come from the more upright position of the gravel bike. The stack on the G + 1 is 25-30mm higher compared to the Vielo R + 1 of the same size.

I am going with the 552 stack on the V+1 in small ( short legs and higher BB) as opposed to 543 in medium on the R+1 so not too big a difference. At 60y of age I can deal with a more comfortable position

[Magnetize6932]

The biggest aero penalty will come from the more upright position of the gravel bike. The stack on the G + 1 is 25-30mm higher compared to the Vielo R + 1 of the same size.

I am going with the 552 stack on the V+1 in small ( short legs and higher BB) as opposed to 543 in medium on the R+1 so not too big a difference. At 60y of age I can deal with a more comfortable position

Gotcha. There are two bikes that might be helpful to look into with your research: Factor uses a wide fork on both the Ostro VAM and Ostro Gravel, where the legs of the fork are far from the wheel, which they claim has aero benefits. Second, the track bike made by Lotus for Team GB has an incredibly wide fork, with the design meant to help shape the flow of air around the rider.

Are either of these analogous to what your situation would be? I have no idea But it does show that lots of space between fork and tire does not necessarily create an aero penalty.

[Hexsense]

^
Note that it's wide on the side but not tall. So, they avoid wind interaction between side of the wheel to the fork blade. While still keep fork crown and down tube close to the tire pointy end.

Forks for gravel bike are tall and down tube recess further from the wheel to allow big diameter tires with good clearance.

[bobinski]

The biggest aero penalty will come from the more upright position of the gravel bike. The stack on the G + 1 is 25-30mm higher compared to the Vielo R + 1 of the same size.

I am going with the 552 stack on the V+1 in small ( short legs and higher BB) as opposed to 543 in medium on the R+1 so not too big a difference. At 60y of age I can deal with a more comfortable position

Gotcha. There are two bikes that might be helpful to look into with your research: Factor uses a wide fork on both the Ostro VAM and Ostro Gravel, where the legs of the fork are far from the wheel, which they claim has aero benefits. Second, the track bike made by Lotus for Team GB has an incredibly wide fork, with the design meant to help shape the flow of air around the rider.

Are either of these analogous to what your situation would be? I have no idea But it does show that lots of space between fork and tire does not necessarily create an aero penalty.

Its good enough for me

[JMeinholdt]

I actually measured out the difference at a set wattage, back-to-back, comparing my 3T Exploro to my Wilier Cento10AIR. The Exploro is billed as an aero gravel bike with fairly racey geometry with a super short head tube. The Wilier is a top spec (at the time) aero race bike.

I set the position up as close as I could make it, which was within a few mm on all of the contact points. The differences were huge. Way more than I expected. TL;DW - you're compromising on any gravel bike with big clearance over a a true aero race bike. Now, my experience is a few years old so maybe the top level gravel race bikes out there narrowed the gap, but I doubt it's been by that much.

https://youtu.be/IqkaU0TC4pI

[warthog101]

Interesting result from the video.
Correlates pretty closely with mine.
Neither of mine are aero bikes but both have 50mm wheels in road trim.
They are a fair bit cheaper than yours I'm guessing.
I do gave a Cervelo S5 with firecrest 404s but no longer ride it due to stupidly tight tyre clearance. Won't fit my tubeless wheel tyre combo.



Prime rr50 v3 on the TCR and Light Bicycle WR50 on the Revolt.
The gravelly has a 28 on the front and a 32 on the rear. The rear comes out at 35mm on such a wide rim. Will swap it for narrower when it wears out.
Bars are both 40cm at the hoods but the gravelly fares to 45 in the drops.
Can't quite get the Revolt bars as low even with a -17° stem but reach is very similar.
Both bikes now have garmin vector3 pedals. I will get around to a comparison at some point but no video, I lack the equipment and am far too ugly.

At a similar power the Revolt is about 1.5kph slower. I am slightly less aero and the gearing is possibly slightly less efficient. 48-11 top gear vs 52-11 on the TCR. Speed differential gets larger the faster you go.