# Reviews/thoughts on the new FLO carbon clinchers?



## BobDobalina (Aug 20, 2012)

Been searching around but I can't for the life of me find any reviews or impressions of FLO's new wheels. Been considering a 45/60 combo for my CAAD10, which I ride mostly on rolling road races. 

All the reviews I can find are on the company's previous-gen wheels. 

Anybody have impressions, or suggestions for something else I should be considering instead? 

Thanks!


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## cobra_kai (Jul 22, 2014)

Probably because no one has them yet. The first order is later this month. There were a couple online reviews:
TriRig.com - FLO Cycling unveils all-new Carbon Clinchers
Flo Cycling 2016 Wheel Line ? First Look - AeroGeeks

There is also a large thread on slowtwitch about them, with a lot of input from the guys at Flo.

In my opinion their level of transparency is fantastic and their design process sounds really good. They will be at or near the top of my list if I ever decide to buy some carbon clinchers.


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## BobDobalina (Aug 20, 2012)

Ahh, apologies, I thought they already had one sale. Thanks, I'll go find the slowtwitch thread.

:edit: Here it is, in case anyone cares:
Flo Cycling Launches Carbon Clinchers!: Triathlon Forum: Slowtwitch Forums


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## cobra_kai (Jul 22, 2014)

If you do end up going in on the April order please post your impressions when you get them. I'm definitely interested in hearing non-reviewer impressions of them.


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## Wesquire (May 27, 2015)

They did all their modeling and optimization for 23c tires. Why would they put themselves years behind at the start?


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## Blue CheeseHead (Jul 14, 2008)

Wesquire said:


> They did all their modeling and optimization for 23c tires. Why would they put themselves years behind at the start?


A wider rim, like HED + makes the installed width of a 23 equal to, or wider than a 25 mounted on a standard 19mm rim. At 200+ lbs I can ride a 23 at 80-90 psi (tubeless) on a 25mm rim without issue. I expect that for a rider at an optimum competitive weight the optimum tire on a wider rim is rightly pegged at 23mm. (BTW, the "c" is part of the rim standard, ie 700c, 650b, not tire width)


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## Wesquire (May 27, 2015)

Blue CheeseHead said:


> A wider rim, like HED + makes the installed width of a 23 equal to, or wider than a 25 mounted on a standard 19mm rim. At 200+ lbs I can ride a 23 at 80-90 psi (tubeless) on a 25mm rim without issue. I expect that for a rider at an optimum competitive weight the optimum tire on a wider rim is rightly pegged at 23mm. (BTW, the "c" is part of the rim standard, ie 700c, 650b, not tire width)


Except it isn't. The wider rims were developed specifically for the increasing popularity of wider tires. The majority of tour riders*use 25mm+ tires, installed on wider rims they frequently measure 27-28mm. That makes the optimum outside diameter of the rim about 27-28mm too. Optimizing for 23mm tires just ignores the trends of the last couple years. For example, the Zipp firecrest rim has a width of 28mm, using a 23mm tire on these new rims just kills the Aero advantage. ENVE is doing the same thing. Optimization for 25mm (measuring more like 27-28) tires has been trend for over two years now, why is FLO going backwards? Why optimize for 23mm when the rest of the cycling world has already moved on to 25/28mm?


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## Wesquire (May 27, 2015)

Blue CheeseHead said:


> (BTW, the "c" is part of the rim standard, ie 700c, 650b, not tire width)


Tell every tire manufacturer to stop labeling them that way then.


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## Blue CheeseHead (Jul 14, 2008)

Wesquire said:


> Tell every tire manufacturer to stop labeling them that way then.


from Tire Sizing Systems

In the French system, the first number is the nominal diameter in mm, followed by a letter code for the width: "A" is narrow, "D" is wide. *The letter codes no longer correspond to the tire width*, since narrow tires are often made for rim sizes that originally took wide tires; for example, 700 C was originally a wide size, but now is available in very narrow widths, with actual diameters as small as 660 mm.


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## Wesquire (May 27, 2015)

Blue CheeseHead said:


> from Tire Sizing Systems
> 
> In the French system, the first number is the nominal diameter in mm, followed by a letter code for the width: "A" is narrow, "D" is wide. *The letter codes no longer correspond to the tire width*, since narrow tires are often made for rim sizes that originally took wide tires; for example, 700 C was originally a wide size, but now is available in very narrow widths, with actual diameters as small as 660 mm.


Tell them, not me. I don't care what the c stands for.


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## Blue CheeseHead (Jul 14, 2008)

Wesquire said:


> Except it isn't. The wider rims were developed specifically for the increasing popularity of wider tires. The majority of tour riders*use 25mm+ tires, installed on wider rims they frequently measure 27-28mm. That makes the optimum outside diameter of the rim about 27-28mm too. Optimizing for 23mm tires just ignores the trends of the last couple years. For example, the Zipp firecrest rim has a width of 28mm, using a 23mm tire on these new rims just kills the Aero advantage. ENVE is doing the same thing. Optimization for 25mm (measuring more like 27-28) tires has been trend for over two years now, why is FLO going backwards? Why optimize for 23mm when the rest of the cycling world has already moved on to 25/28mm?


It depend on the rim width (and rider weight) as to which tire width is optimum. Install a 23mm tire on a HED + rim and you will see the sidewall and brake surface are nearly flush creating beneficial aero and sidewall stiffness benefits. Benefits were noticed in this early review HED Ardennes Plus SL wheelset review - BikeRadar USA

HED used to highlight the shape of the 23mm tire and wind tunnel results on their website as the benefit of the wider + rim. It appears they no longer market that. That is contrary to your assertion that wider rims were developed as a reaction to wider tires. The genesis of the wider rim...per HED was to reduce the lightbulb shape of the installed tire. Hed Ardennes Not Breaking - Making New Rules

There are any number of other articles stating the benefits of 23mm or 25mm rims with 23mm wide tires. I have yet to see one article saying "to meet the demands of a 25mm tire, we are moving to a wider rim". Got any links?


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## MMsRepBike (Apr 1, 2014)

Blue CheeseHead said:


> There are any number of other articles stating the benefits of 23mm or 25mm rims with 23mm wide tires. I have yet to see one article saying "to meet the demands of a 25mm tire, we are moving to a wider rim". Got any links?


Mavic just did this.

In fact they say you can't or rather they recommend against using anything smaller than a 25mm. Now this is because of a standard, an ISO standard, that most can probably agree is a bit ridiculous, but still, it's what they're doing.

I think the standard says that anything over an internal width of 17mm has to be on at least a 28mm tire. So their new road rims have a 17mm internal width exactly which is the limit for 25mm. If they went back to their more narrow rims, they would be able to run 23mm, but they can't on their newer and wider rims, against the standard.


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## Wesquire (May 27, 2015)

Blue CheeseHead said:


> It depend on the rim width (and rider weight) as to which tire width is optimum. Install a 23mm tire on a HED + rim and you will see the sidewall and brake surface are nearly flush creating beneficial aero and sidewall stiffness benefits. Benefits were noticed in this early review HED Ardennes Plus SL wheelset review - BikeRadar USA
> 
> HED used to highlight the shape of the 23mm tire and wind tunnel results on their website as the benefit of the wider + rim. It appears they no longer market that. That is contrary to your assertion that wider rims were developed as a reaction to wider tires. The genesis of the wider rim...per HED was to reduce the lightbulb shape of the installed tire. Hed Ardennes Not Breaking - Making New Rules
> 
> There are any number of other articles stating the benefits of 23mm or 25mm rims with 23mm wide tires. I have yet to see one article saying "to meet the demands of a 25mm tire, we are moving to a wider rim". Got any links?


Surprise, HED is behind the curve too. The state of the art rims are all 27-28mm wide. They are all optimized for 25mm tires.


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## cobra_kai (Jul 22, 2014)

Wesquire said:


> Surprise, HED is behind the curve too. The state of the art rims are all 27-28mm wide. They are all optimized for 25mm tires.


The flo 60 has a max width of 26.9 mm with internal width of 18 mm, which is also important for avoiding a light bulb shape with wide tires. Zipp 404 nsw for example has a max width of 27.8 mm but the internal width is 17.25 mm. Also if you read the recent flo blog post on their tire wind tunnel study you can see that the difference between 23 and 25 mm tires isn't huge. 

http://flocycling.blogspot.com/2016/04/flo-cycling-a2-wind-tunnel-tire-study.html?m=1


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## MMsRepBike (Apr 1, 2014)

So if my internal rim width is 19.5mm and external is 28mm and the tires are 25mm do I win? How wide is too wide for a 25mm?


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## cobra_kai (Jul 22, 2014)

MMsRepBike said:


> So if my internal rim width is 19.5mm and external is 28mm and the tires are 25mm do I win? How wide is too wide for a 25mm?


I don't know what does the wind tunnel say?


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## MMsRepBike (Apr 1, 2014)

In the car world a lot of folks stretch tires. Not for the same reason but this sort of reminds me of that. I'm sure there will be sort of a bell curve or something where at some point it will be stretched too much and not work right. Seems like most are sticking to around a 17mm or 18mm internal for this generation.

It's the internal width that matters for the tire shape right? The external width is more of an aerodynamics thing right? What's the internal width for this new FLO generation? I can see the external but not internal.

I know you can't use them in racing because UCI and such but what about those snap on fairings that Mavic used to have that go between the tire and rim? I'm guessing this new line/generation of wheels coming out from everyone though is trying to address that without them.


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## cobra_kai (Jul 22, 2014)

MMsRepBike said:


> In the car world a lot of folks stretch tires. Not for the same reason but this sort of reminds me of that. I'm sure there will be sort of a bell curve or something where at some point it will be stretched too much and not work right. Seems like most are sticking to around a 17mm or 18mm internal for this generation.
> 
> It's the internal width that matters for the tire shape right? The external width is more of an aerodynamics thing right? What's the internal width for this new FLO generation? I can see the external but not internal.
> 
> I know you can't use them in racing because UCI and such but what about those snap on fairings that Mavic used to have that go between the tire and rim? I'm guessing this new line/generation of wheels coming out from everyone though is trying to address that without them.


It varies based on which rim, but I think they are all between 17 and 18 mm. All the specs are on each product page, internal width, brake track width, max width. The flo stuff is interesting because of how they ran the optimization algorithm for each rim depth. So supposedly for each rim it's the 'best' solution for the imposed constraints. I'd be interested in what kind of optimization techniques they used but their blog post wasn't quite that in depth.


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## MMsRepBike (Apr 1, 2014)

cobra_kai said:


> The flo stuff is interesting because of how they ran the optimization algorithm for each rim depth. So supposedly for each rim it's the 'best' solution for the imposed constraints.


Enve says the same thing, that's how they come up with their weird numbers. Like the 4.5 actually being 48mm and 56mm. FLO sounds solid, they're doing the work. Weird numbers appeal to me more than just standard millimeter dimensions. Nature doesn't operate on that sort of scale.


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## Wesquire (May 27, 2015)

cobra_kai said:


> The flo 60 has a max width of 26.9 mm with internal width of 18 mm, which is also important for avoiding a light bulb shape with wide tires. Zipp 404 nsw for example has a max width of 27.8 mm but the internal width is 17.25 mm. Also if you read the recent flo blog post on their tire wind tunnel study you can see that the difference between 23 and 25 mm tires isn't huge.
> 
> Flo Cycling Blog: FLO Cycling - A2 Wind Tunnel Tire Study Part 1


I think you are missing the point about the 23 vs 25. The 23mm with a matching width rim will be a little more Aero, however the move towards 25mm isn't about aerodynamics. It is about better rolling resistance and better comfort. That's why rims are being optimized for 25mm tires, they are faster and more comfortable. The problem with FLO optimizing for the 23mm is that if you use 25mm tires on them, you lose aerodynamic advantage due to the light bulb effect. If you use 23mm tires, you lose the rolling resistance and comfort advantage. That's why the big players are optimizing for 25mm, you get the rolling resistance, comfort, AND the Aero (albeit a very tiny bit less Aero than a perfectly matched 23mm combo)


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## cobra_kai (Jul 22, 2014)

I'm not missing that at all, I use 25mm tires on both my bikes, and neither is Flo. Which is why they are doing a part 2 of the blog I linked where they sent all of the tested tires to Tom A (<cite class="_Rm">bikeblather.blogspot.com)</cite> for roller resistance testing and then will be writing a post on the fastest overall tire.

Besides, which of the big players, based on your post above I assume you mean enve and zipp, have shown that their wheels are faster with 25mm tires than 23mm? On the Enve SES 4.5 page that they state it was designed for use with 25mm tires but see no data. To quote Deming: "In God we trust, all others bring data." I don't see anything on the Zipp 404 NSW page about being optimized for 25mm. In fact in Zipp's FAQ they state that the best setup is using a 23mm front tire and 25mm rear: Zipp - Speed Weaponry | Support | FAQs . I also found an interesting email from one of Zipp's lead engineers that states they designed around a 23mm tire although a 25 mm tire doesn't increase drag until over 10 degrees of yaw: Tech FAQ: Again, bigger tires roll faster! - VeloNews.com . Unfortunately I can't find the plot he references.

The only other tire study that I am aware of was done by November, another little guy: November Bicycles: Race smart. - November Bicycles Blog - November in the wind tunnel: is wider faster? where both their wide rims and Zipp's 404 were faster using 23 mm tires than 25.


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## Blue CheeseHead (Jul 14, 2008)

Wesquire said:


> Surprise, HED is behind the curve too. The state of the art rims are all 27-28mm wide. They are all optimized for 25mm tires.


HED was at the forefront of wider rims with their C2 and then took it up a notch with the +. The Belgium + while only 25mm outside is 21mm inside (what matters).

Do you have any links to these "state of the art" rims and their wind tunnel tests? Heck I would be curious to see their marking info on how they designed them around the 25mm tire. Seriously, I would be interested in reading them. I have tried Google with no luck.

At 200+ lbs I rode 25s on standard width rims and they were great. I have found no need to run 25s on my Ardennes + wheels as the wider rim makes the 23 have a larger cross section equaling a 25 on a standard rim AND provides a better sidewall profile. I am sure there are aero benefits, but not that I could measure.


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## MMsRepBike (Apr 1, 2014)

Seems to me like for a 25mm tire optimization you'd want to go a bit wider than 18mm internal. Maybe like 20mm or so. With most everyone at 17-18mm internal it's kind of hard to believe they were built for 25s.

In the end though it doesn't matter much at all to us. I recently set a bunch of PRs on some box section training rims on light bulbed out 23s. These fine details can't really matter much to the average joe. Or if I would have been on some new fancy wheels like these new FLO would I have gone even better? I don't care. 

I guess just give me something that looks good and is comfortable and safe. That's plenty for me.

I will probably still pretend to care about the fine details though when in reality I really don't.


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## Wesquire (May 27, 2015)

cobra_kai said:


> I'm not missing that at all, I use 25mm tires on both my bikes, and neither is Flo. Which is why they are doing a part 2 of the blog I linked where they sent all of the tested tires to Tom A (<cite class="_Rm">bikeblather.blogspot.com)</cite> for roller resistance testing and then will be writing a post on the fastest overall tire.
> 
> Besides, which of the big players, based on your post above I assume you mean enve and zipp, have shown that their wheels are faster with 25mm tires than 23mm? On the Enve SES 4.5 page that they state it was designed for use with 25mm tires but see no data. To quote Deming: "In God we trust, all others bring data." I don't see anything on the Zipp 404 NSW page about being optimized for 25mm. In fact in Zipp's FAQ they state that the best setup is using a 23mm front tire and 25mm rear: Zipp - Speed Weaponry | Support | FAQs . I also found an interesting email from one of Zipp's lead engineers that states they designed around a 23mm tire although a 25 mm tire doesn't increase drag until over 10 degrees of yaw: Tech FAQ: Again, bigger tires roll faster! - VeloNews.com . Unfortunately I can't find the plot he references.
> 
> The only other tire study that I am aware of was done by November, another little guy: November Bicycles: Race smart. - November Bicycles Blog - November in the wind tunnel: is wider*faster? where both their wide rims and Zipp's 404 were faster using 23 mm tires than 25.


I really don't see how you guys are still missing the point by so much. I never said 25mm was more Aero. 25mm has better rolling resistance and better comfort. Optimization for the 25mm also makes Aero difference almost nothing. But I'm glad you found an email from about 3 wheel generations ago.


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## cobra_kai (Jul 22, 2014)

Wesquire said:


> I really don't see how you guys are still missing the point by so much. I never said 25mm was more Aero. 25mm has better rolling resistance and better comfort. Optimization for the 25mm also makes Aero difference almost nothing. But I'm glad you found an email from about 3 wheel generations ago.


Once again, I am not missing the point. I use 25mm tires for the comfort reasons you mention. However, I dispute your assertion that companies are optimizing their top end wheels around 25mm tires. I am also asserting that I don't think that it matters - the aero penalty for using a 25mm tire on a 23 mm designed rim is very low. The rolling resistance advantage for using a 25mm tire over a 23 mm tire is also very low: Continental Grand Prix 4000S II 23 25 28 mm Comparison. In fact assuming you run the 25mm tires at lower pressure for comfort you are probably break even or possibly even a little slower than a 23mm tire.


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## Wesquire (May 27, 2015)

cobra_kai said:


> Once again, I am not missing the point. I use 25mm tires for the comfort reasons you mention. However, I dispute your assertion that companies are optimizing their top end wheels around 25mm tires. I am also asserting that I don't think that it matters - the aero penalty for using a 25mm tire on a 23 mm designed rim is very low. The rolling resistance advantage for using a 25mm tire over a 23 mm tire is also very low: Continental Grand Prix 4000S II 23 25 28 mm Comparison. In fact assuming you run the 25mm tires at lower pressure for comfort you are probably break even or possibly even a little slower than a 23mm tire.



You think they are using 28mm+ rims with 23mm tires in mind?


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## cobra_kai (Jul 22, 2014)

Wesquire said:


> You think they are using 28mm+ rims with 23mm tires in mind?


Yes. Not only that, for some companies I think they are designing a 30 mm rim with a 22 mm tire. See Specialized Roval CLX 64: Aero is Everything - Slowtwitch.com (about 2/3 down the page it talks about a 22mm tire designed to fit with the CLX 64)


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## Wesquire (May 27, 2015)

cobra_kai said:


> Yes. Not only that, for some companies I think they are designing a 30 mm rim with a 22 mm tire. See Specialized Roval CLX 64: Aero is Everything - Slowtwitch.com (about 2/3 down the page it talks about a 22mm tire designed to fit with the CLX 64)


You realize that is for a completely different rim shape than FLO or any other brand is using right?


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## cobra_kai (Jul 22, 2014)

Wesquire said:


> You realize that is for a completely different rim shape than FLO or any other brand is using right?


Not really. Specialized definitely took it a step or two further but the idea is that the leading edge and trailing edge should look similar since they trade places as the wheel revolves. 

Regardless, the point remains that I have yet to see any proof other than a few marketing phrases on a website that companies are specifically optimizing for 25 mm tires. If you have any please post the links so we can stop quibbling over minutiae. This thread is already more than derailled.


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## Wesquire (May 27, 2015)

cobra_kai said:


> Not really. Specialized definitely took it a step or two further but the idea is that the leading edge and trailing edge should look similar since they trade places as the wheel revolves.
> 
> Regardless, the point remains that I have yet to see any proof other than a few marketing phrases on a website that companies are specifically optimizing for 25 mm tires. If you have any please post the links so we can stop quibbling over minutiae. This thread is already more than derailled.


Every wheel manufacturer has been saying it for over two years now. The majority of the pro peloton and their mechanics have moved to 25mm, and rim widths keep increasing. I don't know what more you want. Specialized is using a tapered rim, it is completely different than the now standard U shape. 5 years from now, we will be riding 28mm and the rims will be wider still.


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## cobra_kai (Jul 22, 2014)

Wesquire said:


> Every wheel manufacturer has been saying it for over two years now. The majority of the pro peloton and their mechanics have moved to 25mm, and rim widths keep increasing. I don't know what more you want. Specialized is using a tapered rim, it is completely different than the now standard U shape. 5 years from now, we will be riding 28mm and the rims will be wider still.


I want wind tunnel results showing that the aero performance penalty for using a 25 mm tire over 23 mm has either been reversed or shrunk between rim generations. Heck I'd settle for cfd results.


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## Wesquire (May 27, 2015)

cobra_kai said:


> I want wind tunnel results showing that the aero performance penalty for using a 25 mm tire over 23 mm has either been reversed or shrunk between rim generations. Heck I'd settle for cfd results.


https://www.aeroweenie.com/assets/img/data/zippattack.png
So like 6g drag difference at normal yaw angles....which is about 3 seconds over a 40km TT. The rolling resistance improvement of the 25mm more than makes up for that. Also, it is true that if you lower the pressure on the wider tires, you can lose the rolling resistance advantage...but it gives you the ability to opt for more comfort with the same performance as 23mm or the same comfort as the 23mm with better performance. Just pump it up for races. 23mm doesn't give you that option, and the only advantage is a whopping ~6g of drag.


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## November Dave (Dec 7, 2011)

I'll just quickly point out that the majority of contestants at Paris-Roubaix, including all 3 podium positions, used 27mm tubulars. Tubulars run pretty true to size, generally. I'd be willing to be that a Continental 4000s II "25mm" clincher on a rim with an 18+mm bead seat width is wider than those tubulars. Riders generally use wider tires for P-R than for normal events. A Continental 4000s II "23mm" clincher on a rim with an 18mm+ bead seat width is wider than the 23 or 25mm tubulars that pros run as standard fare.


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## Blue CheeseHead (Jul 14, 2008)

Wesquire said:


> https://www.aeroweenie.com/assets/img/data/zippattack.png
> So like 6g drag difference at normal yaw angles....which is about 3 seconds over a 40km TT. The rolling resistance improvement of the 25mm more than makes up for that. Also, it is true that if you lower the pressure on the wider tires, you can lose the rolling resistance advantage...but it gives you the ability to opt for more comfort with the same performance as 23mm or the same comfort as the 23mm with better performance. Just pump it up for races. 23mm doesn't give you that option, and the only advantage is a whopping ~6g of drag.


Well, since you brought Zipp up, when asked if 25's are faster their response:

*



No: Michael Hall, Zipp wheel development director

Click to expand...

*


> “The trend to move to a wider tyre comes with a slight advantage in rolling resistance over narrower tyres. A reasonable-performance improvement when going from a 23mm to a 25mm tyre would be a reduction in rolling resistance of 10 per cent or about three watts at 40kph. However, when evaluating the aero affects of such a change on Zipp Firecrest rims on a TT bike set-up, we found the opposite.”




It comes from Are wider tyres really faster? - Cycling Weekly

"Normal yaw angle". The wind blows in different directions and roads turn. Bikes get hit at all angles. One angle is no more normal than another. 

Looking at your chart. 25's result in anywhere between 6% and 95% more aero drag than a 23.


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## coachboyd (Jan 13, 2008)

cobra_kai said:


> I want wind tunnel results showing that the aero performance penalty for using a 25 mm tire over 23 mm has either been reversed or shrunk between rim generations. Heck I'd settle for cfd results.


I have a bunch of that, but on my computer at home. I will try to post the image later.
Basically, the drag graphs look the same from 0 to 10 degrees of yaw angle with the 23mm tire being about 10 grams of drag lower (at 30mph using a Conti GP4000 tire). At 10 degrees of yaw, the 25mm begins to stall out and the drag increases, whereas with the 23mm tire the drag continues to drop til about 15 degrees yaw angle.

So, in heavy crosswind situations there is a bigger difference in aerodynamics between a 23 and a 25mm tire. 
This is also why there is better crosswind handling using 23mm tires opposed to 25s. In the heavier crosswinds the air flows off the rim over the tire on the backside of the wheel better with a 23mm tire. 
Personally I have been running some 90mm clinchers in a couple races as we are about to release them soon. I am running 23mm tires on those (they look so tiny!) and I have noticed that in a heavier crosswind it feels about the same as running my 60mm clincher set with Michelin Pro 4 25mm tires (which actually measure about 28.6mm).

Will post the graph later tonight, we saw the same trend with almost every wheel we brought to the wind tunnel.


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## Wesquire (May 27, 2015)

Blue CheeseHead said:


> Well, since you brought Zipp up, when asked if 25's are faster their response:
> 
> 
> 
> ...


Again, that is talking about rims that are two generations behind. They are wider now, and the 25mm tires don't have the light bulb effect with the new rims


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## Wesquire (May 27, 2015)

Blue CheeseHead said:


> Well, since you brought Zipp up, when asked if 25's are faster their response:
> 
> 
> 
> ...


How often do you think you are getting effective yaw at 15*+?


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## cobra_kai (Jul 22, 2014)

Wesquire said:


> Again, that is talking about rims that are two generations behind. They are wider now, and the 25mm tires don't have the light bulb effect with the new rims


Actually I'm pretty sure the plot you posted is the one referenced in the velonews article you were so dismissive of earlier. X45 FC is code for Zipp 303 FC clincher according to that article. At this point I think we are just disagreeing over agreeing. I've already said that the aero penalty is minimal and I personally run and will continue to run 25 mm clinchers for comfort.


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## Wesquire (May 27, 2015)

November Dave said:


> I'll just quickly point out that the majority of contestants at Paris-Roubaix, including all 3 podium positions, used 27mm tubulars. Tubulars run pretty true to size, generally. I'd be willing to be that a Continental 4000s II "25mm" clincher on a rim with an 18+mm bead seat width is wider than those tubulars. Riders generally use wider tires for P-R than for normal events. A Continental 4000s II "23mm" clincher on a rim with an 18mm+ bead seat width is wider than the 23 or 25mm tubulars that pros run as standard fare.


Well I know Hayman and many others used 28mm tires and Sagan and many others used 30mm so I don't know where you got that info.


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## cobra_kai (Jul 22, 2014)

coachboyd said:


> I have a bunch of that, but on my computer at home. I will try to post the image later.
> Basically, the drag graphs look the same from 0 to 10 degrees of yaw angle with the 23mm tire being about 10 grams of drag lower (at 30mph using a Conti GP4000 tire). At 10 degrees of yaw, the 25mm begins to stall out and the drag increases, whereas with the 23mm tire the drag continues to drop til about 15 degrees yaw angle.
> 
> So, in heavy crosswind situations there is a bigger difference in aerodynamics between a 23 and a 25mm tire.
> ...


Thanks for joining in coachboyd I am definitely interested in seeing those plots. Once again it's one of the small guys showing the data...


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## November Dave (Dec 7, 2011)

Hayman and Boonen used 28s, Standard used 27s. There was a fuss made about Giant being the only ones to run 30s. Not enough time to find everything I read about it. 

So Boyd's "25mm" Michelin clinchers would have been the widest tires on the podium at P-R. And he's got the legs to get there, too. I don't. 

Take away points: pros use tubulars which are generally much more true to size than clinchers and don't vary at all depending on which rim they're on; clinchers often have no relationship to the size printed on the side and vary quite a bit depending on the rim they're on; pros normally use 23 or 25mm tubulars which are actually those sizes but for P-R they'll run bigger tires.


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## Wesquire (May 27, 2015)

November Dave said:


> Hayman and Boonen used 28s, Standard used 27s. There was a fuss made about Giant being the only ones to run 30s. Not enough time to find everything I read about it.
> 
> So Boyd's "25mm" Michelin clinchers would have been the widest tires on the podium at P-R. And he's got the legs to get there, too. I don't.
> 
> Take away points: pros use tubulars which are generally much more true to size than clinchers and don't vary at all depending on which rim they're on; clinchers often have no relationship to the size printed on the side and vary quite a bit depending on the rim they're on; pros normally use 23 or 25mm tubulars which are actually those sizes but for P-R they'll run bigger tires.


Giant were definitely not the only ones running 30mm. Many others did. Sagan switched to 30mm halfway through.


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## coachboyd (Jan 13, 2008)

ok, as promised (although a bit late) is the wind tunnel graph of a 23mm tire vs. a 25mm tire.

This was the same model GP4000 tire, both set to 100PSI.
This graph is from our 44mm, but almost all of the wheels we tested displayed the same characteristics. From 0-10 the graphs look the same, just different drag numbers. At 12.5 the 25mm tire stalls and that is where the 23mm tire starts doing much better aerodynamically.

This graph is not labeled, but grams of drag are on the left, and the yaw angle is on the bottom.


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## Wesquire (May 27, 2015)

coachboyd said:


> ok, as promised (although a bit late) is the wind tunnel graph of a 23mm tire vs. a 25mm tire.
> 
> This was the same model GP4000 tire, both set to 100PSI.
> This graph is from our 44mm, but almost all of the wheels we tested displayed the same characteristics. From 0-10 the graphs look the same, just different drag numbers. At 12.5 the 25mm tire stalls and that is where the 23mm tire starts doing much better aerodynamically.
> ...


Thanks. Do you know the rim and tire measured widths? You would expect less difference between them the wider the rim gets.


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## coachboyd (Jan 13, 2008)

This is with our new carbon, so 19mm internal / 27mm external. 

I can't remember actual tire widths off the top of my head, but I believe the 23mm was mid 25's and the 25mm was just over 27.


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## jsf1993 (Jul 3, 2007)

coachboyd said:


> ok, as promised (although a bit late) is the wind tunnel graph of a 23mm tire vs. a 25mm tire.
> 
> This was the same model GP4000 tire, both set to 100PSI.
> This graph is from our 44mm, but almost all of the wheels we tested displayed the same characteristics. From 0-10 the graphs look the same, just different drag numbers. At 12.5 the 25mm tire stalls and that is where the 23mm tire starts doing much better aerodynamically.
> ...


Given these results, Coachboyd, do you recommend 23 mm over 25 mm GP4000's for your new 44 Carbon wheels?

Thanks!


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## coachboyd (Jan 13, 2008)

jsf1993 said:


> Given these results, Coachboyd, do you recommend 23 mm over 25 mm GP4000's for your new 44 Carbon wheels?
> 
> Thanks!


Nope, unless you are purely doing time trials (which you would probably not be doing on 44s). 
25mm tires have lower rolling resistance, better handling, can be run at lower PSI for better vibration dampening. All of those thing for the vast majority of riders is going to far outweigh the 10 grams of drag at 30mph difference you may see.
I've actually started using 28mm tires for a lot of my hillier rides.


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## cobra_kai (Jul 22, 2014)

coachboyd said:


> ok, as promised (although a bit late) is the wind tunnel graph of a 23mm tire vs. a 25mm tire.
> 
> This was the same model GP4000 tire, both set to 100PSI.
> This graph is from our 44mm, but almost all of the wheels we tested displayed the same characteristics. From 0-10 the graphs look the same, just different drag numbers. At 12.5 the 25mm tire stalls and that is where the 23mm tire starts doing much better aerodynamically.
> ...


Thanks for the plot. That looks very similar to the data flo published, although I think their 25 stalled closer to 15 degrees. My takeaway is regardless of how the wheels are being designed, there is a minimal aero penalty for using 25 mm tires but many other benefits.


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## MMsRepBike (Apr 1, 2014)

Question for Coach:

Thanks for being here by the way. In order to "optimize for a 25mm tire" does there need to be a minimum internal width/bead seat? It seems odd that a 17mm internal and a 19mm internal would perform similar with the same tire. We know that up to 18mm or so it all seems to be optimized for a 23. I see you're doing 19mm internal now, is that to counter the lightbulb effect? Is it for 25mm+ tires primarily?

What I'm getting at is that external width of a rim basically seems to mean nothing in terms of tire size choice. Now a days the widest part seems to be either the very bottom of the brake track or even below that. More about air than tires for sure. The internal width though seems to be all about tires and how they seat and the profile they make on the rim. Am I on track here?

I'm not looking for a magic bullet like up to 19mm should be 23 and over 19mm should be 25 or whatever, but I'm guessing there's some sort of correlation there.


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## Wesquire (May 27, 2015)

MMsRepBike said:


> Question for Coach:
> 
> Thanks for being here by the way. In order to "optimize for a 25mm tire" does there need to be a minimum internal width/bead seat? It seems odd that a 17mm internal and a 19mm internal would perform similar with the same tire. We know that up to 18mm or so it all seems to be optimized for a 23. I see you're doing 19mm internal now, is that to counter the lightbulb effect? Is it for 25mm+ tires primarily?
> 
> ...


Tire selection and "optimization" are dependent on both the beat seat and the maximum rim diameter. For example... 19mm internal and 28mm outer...25mm tires are optimized. For 19mm internal and ~26mm outer, 23mm tires are optimized. For 18mm internal and 27mm outer, 25mm tires would be optimized. Basically, you want the measured widths of the tire and rim to be the same. The bigger internal, the wider the tire will be.


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## Dunbar (Aug 8, 2010)

Flo Cycling did a bunch of testing and concluded that riders spend 80% of their time between 0-10 degrees of yaw. So I wouldn't be too concerned about the high yaw angle drag penalty of running a 25mm front tire.

FLO Cycling - Wheel Design Series Step 2 - Data Analysis


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## 195cranky (Jun 25, 2013)

I don't have data. I don't have charts and graphs. I don't bring out the digital calipers. I don't care about fads or trends. What I do have is real world experience with FLO wheels. I do own and use:

FLO 30's three pairs. One custom built rear with PowerTap with 30 rim.
FLO 60 pair
FLO 90 pair
FLO disc for TT rear. Obviously.

I do find over the years that FLO wheels are; well built, strong, reliable, stay true, good quality, great guys to work with, passionate, and most importantly offer a clyde build rear. Why is that important? It is important cause at 6'5" and 195 to 230 pounds - I am a clyde. I need good strong wheels. Wheels that get me home or to the finish line. Not light weight save a few grams fragile garbage that is out there.

I ride 30's tubeless, latex tubed, or butyl tubed. And ride quality is in that order. I have tried 23, 25, and now Spesh 24 and 26. I used 23 on 60, 90, and disc. Now 26 on 90/90 and disc. I ride 80/85 f/r up to 90/95 pressures depending on wheel and conditions. 

Here are some real world impressions. Remember, these impressions to you are worth as much as you have paid to get them. 25's are not needed. As soon as 26's wear out will go down to Spesh 24. 23's feel optimized for shape, grip, wear, width and pressure range for my riding needs. The Spesh 24 work fine also as a wider tire over 23 Conti, Bontrager, Spesh, Hutchi, Maxxis, Schwalbe that I have tried over the years and 26 is really not needed. I will stick with 23 or 24. Is that faster? I don't know. I went out on TT bike on 23, next day on 26 and I was flying on the 26. The big tailwind helped I had on second day. Helped big time when I sustained 29mph plus and said to myself that 26 tire is fast. Then going back homer the 26's sucked in the headwind. Maybe that was just me? Maybe the yaw angle was too great? Or is less better? All I know was the hee-yaw with tailwind made me feel like TT Fabian of old. If I was tubeless then it was have been Tony Tubeless minus the ill-timed one flat that may have derailed people from figuring out tubeless is awesome. 

Is 26 more comfy? Sure, so is a wide, long, fat caddy but I would not want to drive one around a race track. 

So the 19, 20, 22, 23, 24, 25, 26, 28, or cringe 30 debate rages on. Ride what works for you. Ride pressures that work for you. Ride wheels and rim widths that work for you. Ride tubeless or tubed or tubular. Don't matter what others say or post. Especially don't matter what marketing departments spit out. The more you ride the more you will learn. Because you will get faster, stronger and will wear out tires quicker. Thus replace with different things to try and analyze what seems right for you. I like tubeless. I like FLO product. I like having a fleet of wheels as a quiver to pick with out the Zippy ridiculous cost or the Envy of others admiring my wheel wallet. My FLO cost to ride benefit is unmatched. 

Can't wait try carbon 45. I think they will make me climb faster, put out more watts, step on the podium, get an offer from a pro team, OK maybe just a jersey from a fat masters team, or even win the town line sprint Thursday World Championships. If the FLO bros see this post and need a marketing department - call me! You got my number...ha...actually credit card number that is.


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## Wesquire (May 27, 2015)

I think the need for "heavy duty" wheels as a 225 lbs + rider gets over exaggerated. Carbon wheels handle the weight MUCH better than aluminum. Hell, I was 235 lbs last year and I never even had a problem with my 20/24 chinese carbon wheels. On top of that I'm a sprinter so if they can handle the daily abuse of 235 lbs and 1200+ watts, I'm not sure who needs anything more. Of course, I could just be extremely lucky...but after 5k+ miles on them, I'm not worried.


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