Brilliant video, Josh. We hear so many marketing pitches for aerodynamically efficient wheels and components but rarely are we ever provided such an excellent presentation. I studied aerodynamics for a few years at Embry Riddle and very much enjoy this visualization of different airfoils applied to rim shapes. I have wondered how the sharper trailing edge airfoils compared to the blunt models. As always, thanks for the great content!
Thanks Will! Yes, we will get to these topics in a future episode 105 Part 2 which will cover handling, stability and when you want blunt vs when you want sharp! Stay tuned!
Josh, thank you for the visual representation for the "Rule of 105" now I get it. Along time ago with a very different project the wheel and tire being an airfoil were discussed at length when we did early wind tunnel testing for the US National TT Record attempts at Moriarity, NM. We most definitely did not have any 'aero-dynamasists' working with us. We were for the most part all lay people getting to play in a wind tunnel developed for Indy car. Still amazed how after all these years Frey's 40K amateur record of 47:35:37 from 9/2/90 of has stood the test of time. So much has changed in training, aerodynamics and even bearings and yet his record still stands
Frey's bike for the '90 record run was a masterclass in aerodynamics, both for its day but also in the modern era. It was essentially an hour record bike with an aero front brake, skinny aero tubing and no base bar.. and of course, an absolutely phenomenal engine!! Knowing what I do about both bikes, I would guess that the Frey bike was more efficient aerodynamically than the Campanaerts hour record bike.
Kind of the reason why fast rolling tires like the Sworks turbo cotton or Vittoria corsa speed with thin treads have worse aero properties compared those with thicker treads such as Schwalbe pro one or Continental GP5000. The thicker tread creates a more "pointed" sectional shape which better resemble the naca profile. While the thinner thread tires approximates to a simple cylinder at the leading edge.
Well I just found your videos today and wow...THIS is the kind of bicycle nerdery I LOVE. Your Tools are awesome BTW. The T-Ratchet + Ti Torque kit and use it all the time.
@@SILCAVelo Actually already shared it with my father who is a retired physics professor and avid cyclist. He suggested the helmet would be a good place to look at for gains...so I then shared video 0008 with him. lol
Silca delivering with TH-cam gold again! I asked ENVE about the rule of 105% in relation to gravel because I feel that is still a nascent field in terms of aero, but they feel that any type of tyre tread completely negates the advantages of a wider wheel, and looking at those flow separation examples at the end tend to make me agree, however it looks like Hunt is developing an ultra wide gravel wheel and has some wind tunnel data (along with Specialized) suggesting that even with tire knobs, the wider wheel is measurably faster. There must be something else, other than flow separation going on in these cases because surely the flow is separating at the tire knobs and with some turbulence, so I don’t see how it could reattach even with a 105%+ rim width. Would love to hear an all off-road marginal gains podcast episode!
Thanks for the thoughts and question... I have little data on this for gravel width tires, but we know from previous tunnel testing (I did at Zipp, and also one done by Trek) that showed even aero rims narrower than the knobby tires still had some positive effect.. FLO Cycling also recently did some work on this for gravel and saw benefits. My hunch is that a rule of 105 rim on a knobby tire might help even more as the rim would effectively grab and calm the turbulent air off of the tire, but that's just a guess! Of course, 50mm wide rim with 47mm tire would look a bit odd (at least at first!) and weight might ben an issue as people still seem to be paying attention to that..
I called Zipp sometime in 2002 maybe 2003 and asked what the recommended tire width was for my 404 tubulars and I was told 19mm. My Zipps had always been race wheels so they still wear 19mm tires, but since they're so old, I've started using them for the local group rides instead of Mavic Open Pro with 700x25c Clinchers. This was very interesting.
bla bla bla bla, just tell me what tires to run on my vanquish wheels! :-P kidding... awesome info and really enjoy all the tech that silca puts out. all the up front and transparent tech speaks to your credibility.
So basically, you must have your measured tyre width smaller than your rim-lip width (105 rule), and your mid-rim width wider than your tyre/rim-lip width, in order to have the highest aero advantage from you wheelset. So tyre width = 24mm, rim-lip width = 25mm, middle of rim = 27mm(more or less). Is this correct ?
Thanks a lot for this brilliant explanation. I have a modern wheel with a 25mm wide braketrack. The rim is 28mm wide at the widest point which is about 30% in. I run 25c Corsa speeds on it, they inflate to 26 on the 19mm rimbed. So with the tyre exceeding the braketrack I lose the air attachment. Now recently we hear so much buzz about wide tyres being faster. How much are the aero losses in comparison to the RR gains?
This will depend on your average speed.. at lower speeds, the rolling resistance is dominant, but at higher speeds, aerodynamics overtake. We would have to do some wind tunnel for your specific setup, but as you are already on pretty much the fastest tire out there, and a wheel that does exceed the tire width at some point in the profile the tradeoffs here will be quite small. In my experience, the crossover is generally in the 20-24mph range for good equipment, and you might be giving up 2-3 watts at 30mph due to the wider tire, while gaining 1 watt or so at 20mph due to improved rolling. For most of us non TT racers and non-pros, the tradeoffs in percentage terms will most always favor the slightly wider tire.
@@SILCAVelo hey guys, thanks for coming back to this! I now replaced the 25mm Corsa speed up front after a puncture by a 23c GP5000 that sits pretty flush with the wheel at 24,3mm width on the 60mm deep rims. Since I ride at 37-38kph at triathlon events this propably isn't the worst choice. :)
Depends on the rim design, yaw and by how much you are breaking it!! For V shaped rims, it can be quite dramatic at yaw angles above 5 degrees, I've seen drag more than double at 10 degrees from tire being 1mm wider than rim. For more modern designs, breaking the rule begins to decrease the stall angle of the wheel.. so you might be similar drag at low yaw, but penalties can get steep at high yaw.. once the tire is more than about 5% larger than the rim, the entire system becomes aero dominated by the tire.. so you still get the advantage of the aero wheel using fewer/shorter spokes than a non deep section wheel.
@@SILCAVelo Thanks for the reply! It is a modern rim (Roval CL 50). I guess it is very difficult to find out without a wind tunnel as a Chung test cannot give you the yaw sweep (?). I live in Denmark where it is quite windy and I am not fast, so I probably spend some non-trivial amount of time at higher yaw angles
In your calculator, chip seal is a pretty bad/rough surface. Most of the secondary roads around here are chip seal. I don't think it's as bad as you make it out to be. I've ridden worn, cracked, broken pavement and chip seal without these problems is way smoother.
Just found these bike nerd tech videos. Super under rated! I can’t wait to binge them all.
Josh- what an amazing breakdown. Super appreciate the time and effort put into making this knowledge accessible to the everyday folk
Thanks!
@@SILCAVelo Totally agree!
These posts are great, like Silca products. It’s why my 80’s circa track pump still works! Great info here, and all the other posts.
Thanks!
HA! My early '70s circa orange track pump still works perfectly! 👍
Best equipment videos out there. LOVE this content.
Brilliant video, Josh. We hear so many marketing pitches for aerodynamically efficient wheels and components but rarely are we ever provided such an excellent presentation. I studied aerodynamics for a few years at Embry Riddle and very much enjoy this visualization of different airfoils applied to rim shapes. I have wondered how the sharper trailing edge airfoils compared to the blunt models. As always, thanks for the great content!
Thanks Will! Yes, we will get to these topics in a future episode 105 Part 2 which will cover handling, stability and when you want blunt vs when you want sharp! Stay tuned!
Josh, thank you for the visual representation for the "Rule of 105" now I get it. Along time ago with a very different project the wheel and tire being an airfoil were discussed at length when we did early wind tunnel testing for the US National TT Record attempts at Moriarity, NM. We most definitely did not have any 'aero-dynamasists' working with us. We were for the most part all lay people getting to play in a wind tunnel developed for Indy car. Still amazed how after all these years Frey's 40K amateur record of 47:35:37 from 9/2/90 of has stood the test of time. So much has changed in training, aerodynamics and even bearings and yet his record still stands
Frey's bike for the '90 record run was a masterclass in aerodynamics, both for its day but also in the modern era. It was essentially an hour record bike with an aero front brake, skinny aero tubing and no base bar.. and of course, an absolutely phenomenal engine!! Knowing what I do about both bikes, I would guess that the Frey bike was more efficient aerodynamically than the Campanaerts hour record bike.
Kind of the reason why fast rolling tires like the Sworks turbo cotton or Vittoria corsa speed with thin treads have worse aero properties compared those with thicker treads such as Schwalbe pro one or Continental GP5000. The thicker tread creates a more "pointed" sectional shape which better resemble the naca profile. While the thinner thread tires approximates to a simple cylinder at the leading edge.
Is this a fact from some source as well. U make sense but would love to know if it's on internet as well
Well I just found your videos today and wow...THIS is the kind of bicycle nerdery I LOVE. Your Tools are awesome BTW. The T-Ratchet + Ti Torque kit and use it all the time.
Thanks John, love to hear it!! Please share with all of your super nerdy friends. - Josh
@@SILCAVelo Actually already shared it with my father who is a retired physics professor and avid cyclist. He suggested the helmet would be a good place to look at for gains...so I then shared video 0008 with him. lol
Legend. Thanks for the education, as always!
Silca delivering with TH-cam gold again! I asked ENVE about the rule of 105% in relation to gravel because I feel that is still a nascent field in terms of aero, but they feel that any type of tyre tread completely negates the advantages of a wider wheel, and looking at those flow separation examples at the end tend to make me agree, however it looks like Hunt is developing an ultra wide gravel wheel and has some wind tunnel data (along with Specialized) suggesting that even with tire knobs, the wider wheel is measurably faster. There must be something else, other than flow separation going on in these cases because surely the flow is separating at the tire knobs and with some turbulence, so I don’t see how it could reattach even with a 105%+ rim width. Would love to hear an all off-road marginal gains podcast episode!
I wouldn't trust anything Hunt says. Some of the data they've posted in the past didn't include spokes🤦. I think they are heavily driven by marketing.
@@edrcozonoking We could always ask Aerocoach.
Thanks for the thoughts and question... I have little data on this for gravel width tires, but we know from previous tunnel testing (I did at Zipp, and also one done by Trek) that showed even aero rims narrower than the knobby tires still had some positive effect.. FLO Cycling also recently did some work on this for gravel and saw benefits. My hunch is that a rule of 105 rim on a knobby tire might help even more as the rim would effectively grab and calm the turbulent air off of the tire, but that's just a guess! Of course, 50mm wide rim with 47mm tire would look a bit odd (at least at first!) and weight might ben an issue as people still seem to be paying attention to that..
@@SILCAVelo Very interesting, thank you for the reply!
I was thinking that too. About tread. I too would like another off road pod ep. (the Leadville ep kind of counts).
Excellent Josh. Thank you.
Thanks! - josh
Music?? Why??
I cannot believe this doesn’t have 1,000,000 views…!! BTW 105 valid for FRONT TIRE right?
I called Zipp sometime in 2002 maybe 2003 and asked what the recommended tire width was for my 404 tubulars and I was told 19mm. My Zipps had always been race wheels so they still wear 19mm tires, but since they're so old, I've started using them for the local group rides instead of Mavic Open Pro with 700x25c Clinchers. This was very interesting.
Thank you Master.
bla bla bla bla, just tell me what tires to run on my vanquish wheels! :-P kidding... awesome info and really enjoy all the tech that silca puts out. all the up front and transparent tech speaks to your credibility.
Thank you sir!
Thanks for the terrific explanation
Thanks Mark! - Josh
Brilliant data
Where can I watch part two?
excellent.
Thanks Ed!
How does the external width of a wheel affect tire width? Thanks!
The external width does not change the measured width but the internal does and is often correlated with the external width.
Anti-Ice boots on wing leading edges...kinda like a tire on the front of the airfoil.
Will this help offset my wearing a baggy tshirt?
Maybe, but just a little bit ;-)
@@SILCAVelo Depends?
So basically, you must have your measured tyre width smaller than your rim-lip width (105 rule), and your mid-rim width wider than your tyre/rim-lip width, in order to have the highest aero advantage from you wheelset. So tyre width = 24mm, rim-lip width = 25mm, middle of rim = 27mm(more or less). Is this correct ?
Thanks a lot for this brilliant explanation. I have a modern wheel with a 25mm wide braketrack. The rim is 28mm wide at the widest point which is about 30% in. I run 25c Corsa speeds on it, they inflate to 26 on the 19mm rimbed. So with the tyre exceeding the braketrack I lose the air attachment. Now recently we hear so much buzz about wide tyres being faster. How much are the aero losses in comparison to the RR gains?
This will depend on your average speed.. at lower speeds, the rolling resistance is dominant, but at higher speeds, aerodynamics overtake. We would have to do some wind tunnel for your specific setup, but as you are already on pretty much the fastest tire out there, and a wheel that does exceed the tire width at some point in the profile the tradeoffs here will be quite small. In my experience, the crossover is generally in the 20-24mph range for good equipment, and you might be giving up 2-3 watts at 30mph due to the wider tire, while gaining 1 watt or so at 20mph due to improved rolling. For most of us non TT racers and non-pros, the tradeoffs in percentage terms will most always favor the slightly wider tire.
@@SILCAVelo hey guys, thanks for coming back to this! I now replaced the 25mm Corsa speed up front after a puncture by a 23c GP5000 that sits pretty flush with the wheel at 24,3mm width on the 60mm deep rims. Since I ride at 37-38kph at triathlon events this propably isn't the worst choice. :)
What is the penalty of breaking the rule? Let's say you have a 29mm wide tire on 28mm aero rim as opposed to a 26mm wide tire
Depends on the rim design, yaw and by how much you are breaking it!! For V shaped rims, it can be quite dramatic at yaw angles above 5 degrees, I've seen drag more than double at 10 degrees from tire being 1mm wider than rim. For more modern designs, breaking the rule begins to decrease the stall angle of the wheel.. so you might be similar drag at low yaw, but penalties can get steep at high yaw.. once the tire is more than about 5% larger than the rim, the entire system becomes aero dominated by the tire.. so you still get the advantage of the aero wheel using fewer/shorter spokes than a non deep section wheel.
@@SILCAVelo Thanks for the reply! It is a modern rim (Roval CL 50). I guess it is very difficult to find out without a wind tunnel as a Chung test cannot give you the yaw sweep (?). I live in Denmark where it is quite windy and I am not fast, so I probably spend some non-trivial amount of time at higher yaw angles
In your calculator, chip seal is a pretty bad/rough surface. Most of the secondary roads around here are chip seal. I don't think it's as bad as you make it out to be. I've ridden worn, cracked, broken pavement and chip seal without these problems is way smoother.
Your frame pumps have been first class dog whackers over the years.
The most important question is, what is your video lighting set up? Looks professional!! (great info/content, btw...thanks!)
No lighting at all on these videos, that's me sitting at a table in front of a 4x8 foot window, so it's just sunlight coming in!
Hi Josh, can I have your permission to translate and repost your video in China?
Yes, but please send us the link and credit SILCA with link to our website.
@@SILCAVelo ok so where should I send the link to? which email?
Must link up with hambini aged 5 for a duo aerodynamics video.. would be absolutely awesome 👏
Or Leutchner
First thumb. What's up, youtube??
I get it. Ha. Thanks.