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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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Slowman wrote:
i can see now i asked the wrong question. the question i SHOULD have asked is what tire width you feel your next bike should accommodate. i will ask that in the next poll

If you could fit 28 mm on your bike and they had lower crr and just as aero as thin tires the only remaining reason to not race on 28mm would be rotational weight of the larger tire. Probably the only reason a 28mm tire or 32mm is less aero is the mate structure to rim, and rim depth. The other issue would be brake clearance and if your tire keeps getting bigger your overall wheel does so your gearing kind of changes.
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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I think it really boils down to what people cant fit and what they have. I don't think any reasonable person is going to go replace their entire wheelset or bike to add 2mm to a tire to maybe save some time.

That being said...

I have 25s on the training wheels for my TT bike, but race on 23s. Because thats what my race wheels can handle.

I have 28 tubless on my road bike...because when I'm riding that I don't care about speed. I just want comfortable time in the saddle and not have to deal with flats.
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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Slowman wrote:
i can see now i asked the wrong question. the question i SHOULD have asked is what tire width you feel your next bike should accommodate. i will ask that in the next poll

agreed. and you should do an article with a panel of industry people. it is surprising how limited their designs (still) are.
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Re: Tire Width (I don't get it) [DarkSpeedWorks] [ In reply to ]
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DarkSpeedWorks wrote:
But, if speed is the goal, how are we to know what is the optimal tire width that our next frame should accommodate? Especially when there is no good data.

well, what i'm now seeing is that wider is faster, if you just look at Crr. not because i know. just because i can read. and what it seems to me that i'm reading, altho i haven't gone back and catalogued this, is that we don't really yet know how wide you can go before you stop getting faster. love to see what tom a. has to say about this.

but, as an example, go here and look at the results of the tire most of you are riding. assuming the rim is wide enough to accept the tire with a good config, you tell me why my next tri bike shouldn't be optimized for 28mm tires.

Dan Empfield
aka Slowman
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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Slowman wrote:
splain me this. and tell me if i've got a problem with my reasoning.

1. 25mm is testing better than 23mm in most rolling resistance tests.
2. in the limited amount of testing i've seen, isn't 28mm outrolling 25mm?
3. wider tires are also likely to be more comfortable (lower pressures).

but...

4. almost 6 in 10 are choosing 23mm or thinner.

yes, there are aerodynamics to consider as well. is this your argument? or is there something wrong with my chain of reasoning above?

I think your premises 1 and 2 might be flawed...at a given pressure, yes, but as you point out, wider tires are typically run at lower pressures. For example, from an article right here on this site:


If you look at reasonable pressures for each tire size, you'll see that there isn't much difference in the Crr...in other words, the horizontal yellow line is more reasonable than the vertical yellow line, in regards to how tires are actually run.

So, if that's the case (and there isn't really any great Crr benefits from wider tires), for a RACE bike, I'm going to be following Josh Poertner's "Rule of 105" https://silca.cc/...ure-and-aerodynamics

To me, the driving factor for choosing tire width for a given application is the tire pressure I want to run for a given course. In other words, if the course conditions require lower pressures for comfort reasons, then I'm going to choose a tire width that allows for that pressure without causing other concerns, such as bottoming rims and/or "snakebite" flats. Of course, expected speeds/wind angles also comes into that calculus. This is how I ended up selecting 42mm wide tires for BWR this year...knowing the amount of off-road conditions, I basically wanted to be able to run close to MTB pressures ;-)

That type of thinking is somewhat opposite of how most folks approach the subject (i.e. pick a tire width and then ask "what pressure should I run?"...I like to think that it's not that wider tires allow lower pressures, but lower pressures require wider tires ;-)

Additionally, the ROT that "wider is lower Crr" is mainly only applicable across a given tire model (and at a given pressure, as pointed out above), so there's that. For example, the fastest tire (by far) on my testing chart is a 23C (Vittoria Corsa Speed)...so, I think many are aware that there ARE fast rolling narrower tires, and that could be coming into play. "Wider is faster rolling" is a generality that has some notable exceptions.

Also, as Greg K. points out above, with wider rims, 23s are the new 25s :-) You really should be asking about "mounted width".

http://bikeblather.blogspot.com/
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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Slowman wrote:
assuming the rim is wide enough to accept the tire with a good config, you tell me why my next tri bike shouldn't be optimized for 28mm tires.

Because it should be optimized for 30mm tires (measured).

Oh shit, anything over about 28mm should have disc brakes. Maybe your next tri bike should be optimized for 30mm tires AND disc brakes. Does anyone know if they are going to start making road/tri bikes any time soon?

/kj

http://kjmcawesome.tumblr.com/
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Re: Tire Width (I don't get it) [devashish_paul] [ In reply to ]
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devashish_paul wrote:
Slowman wrote:
i can see now i asked the wrong question. the question i SHOULD have asked is what tire width you feel your next bike should accommodate. i will ask that in the next poll


If you could fit 28 mm on your bike and they had lower crr and just as aero as thin tires the only remaining reason to not race on 28mm would be rotational weight of the larger tire. Probably the only reason a 28mm tire or 32mm is less aero is the mate structure to rim, and rim depth. The other issue would be brake clearance and if your tire keeps getting bigger your overall wheel does so your gearing kind of changes.

And that's not even actually a legitimate reason...

http://bikeblather.blogspot.com/
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Re: Tire Width (I don't get it) [Tom A.] [ In reply to ]
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what i see from BRR is that wider tires at high pressures test fast. but then there's the impedance (?) factor, which josh has been testing, maybe you have as well, and i suspect this relates to road surface? for example, maybe 28mm @ 120psi might be a really fast tire/pressure on a very smooth velodrome? as long as the wheel, the bike, and the aerodynamics all played nicely.

the thing is, once you get to a rougher road, it still seems to me that this argues for a larger tire, just @ lower pressure.

i'm asking because i've got bike companies right now in the process of designing their next bikes and they're wondering what to design for. it didn't occur to me that there was so much of a problem with people just not able to put the tires in their bikes, but of course that's true now that i think of it.

Dan Empfield
aka Slowman
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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Slowman wrote:
Bonesbrigade wrote:
Most low crr 23mm tires test faster than 25mm tires when aero is factored in. Plus, many frames still do not fit wide rims with 25mm tires.


i'm not disputing you, but do you know this? how many tires have been tested on how many wheels? seems like there must be a lot of aero testing left undone in order to make a broad claim like this. if the 25mm tires on balance outroll their 23mm siblings, then the 23mm tires MUST perform better aerodynamically just to get back to even.


Here's one example of looking at that question:

http://bikeblather.blogspot.com/...t-3-after-party.html

Aero differences of the same tire models in different widths:


What happens when you factor in Crr:


As you can see, just looking at the SW Turbo models, the lower Crr of the 28C model isn't enough to overcome the better aerodynamics of the 26C and 24C models, which are basically "tied" out to 10 deg (BTW, the 22C model of that tire is a pretty huge outlier in regards to Crr for some reason, which is why it's excellent aerodynamics can't be taken advantage of).

Of course, those charts also show that the Turbo Cottons (both 26C and 24C models) outperform the rest due to their significantly lower Crr, despite worse drag at yaws greater than 5 degrees.

http://bikeblather.blogspot.com/
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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Slowman wrote:
what i see from BRR is that wider tires at high pressures test fast. but then there's the impedance (?) factor, which josh has been testing, maybe you have as well, and i suspect this relates to road surface? for example, maybe 28mm @ 120psi might be a really fast tire/pressure on a very smooth velodrome? as long as the wheel, the bike, and the aerodynamics all played nicely.

Yeah...you're going to have a problem with that. Good luck getting a 28C tire to stay on a rim at 120psi. The casing tension on that is going to be ENORMOUS.

And yes, I've tested "impedance"...in fact, my first data is what Josh points to. And also yes, that comes into play at all tire widths, and is a function of road surface, load, tire, and speed (i.e. input energy).

Slowman wrote:
the thing is, once you get to a rougher road, it still seems to me that this argues for a larger tire, just @ lower pressure.

No...it argues for lower pressures, which require larger tires "to play nicely" (re-read my post above)

Slowman wrote:
i'm asking because i've got bike companies right now in the process of designing their next bikes and they're wondering what to design for. it didn't occur to me that there was so much of a problem with people just not able to put the tires in their bikes, but of course that's true now that i think of it.

Just tell them to design for the widest measured tire width (and height, in regards to GP4Ks) for the brakes they've selected for the application. For most rim calipers, that's going to be ~28mm, unless they spec mid or long reach calipers, or design their own rim calipers.

For hub calipers (i.e. "discs") then it's basically wide open ;-)

http://bikeblather.blogspot.com/
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Re: Tire Width (I don't get it) [Tom A.] [ In reply to ]
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stipulating that i'm well out of my depth here, do i understand that you tested all of the turbo cotton widths on the same roval CLX64? i ask because i believe i remember specialized making some noise about this wheel being built around the turbo cotton for aerodynamics. so, unless i dreamed that, then it must follow that specialized had a particular width of its turbo cotton in mind and i'd be willing to bet it wasn't the 28mm.

but i don't know if i understood your test to be 3 tires on that same wheel. but if so, then i guess i speculate what could be achieved, theoretically, had specialized gone back and designed another roval optimized now to the 28mm tire. now it no longer has that 21mm internal bead diamater but 23mm or 24mm or whatever. is my reasoning sound or am i off on a wild one?

but it could also be that there's something about a 28mm tire on a 21mm internal bead rim that makes it roll faster and if you placed it on a fatter rim maybe the Crr of that wider tire comes down to earth.

anyway, the point of this speculation is to have a good answer for bike makers who're wondering whether they need to make their new frames and forks to fit 23mm, 25mm, 28mm or what?

Dan Empfield
aka Slowman
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Re: Tire Width (I don't get it) [Tom A.] [ In reply to ]
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Tom A. wrote:
Just tell them to design for the widest measured tire width (and height, in regards to GP4Ks) for the brakes they've selected for the application.

moot point ;-)

Dan Empfield
aka Slowman
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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Two reason I still run 23mm tires...

1. I ride older areo wheels so the wider tire look light a light bulb on my narrow rims. Seems like that would negate any areo benefit. (Fix for that of course is me not being so cheap and buying newer wheels that are wider)

2. I ride 650c wheels and Continental doesn't make their 4000s in anything but 23mm for the 650c size. (Fix for that is a whole different bike, which often comes with toe overlap for my height-challenged size)
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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Slowman wrote:
Tom A. wrote:
Just tell them to design for the widest measured tire width (and height, in regards to GP4Ks) for the brakes they've selected for the application.


moot point ;-)

If that's the case, tell them to design around 50mm width tires...'cuz some dork is going to insist that's what they absolutely need :-P

http://bikeblather.blogspot.com/
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Re: Tire Width (I don't get it) [gregk] [ In reply to ]
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I hear you about the Michigan roads! Thankfully I can run 25s on my Felt S22. With latex tubes it is okay, but definitely not great.

Aaron Bales
Lansing Triathlon Team
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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I am with you.

This is becoming more well known, and I think wheel/tire systems will develop to recognize this reality.

You need really wide internal measurements to make a bigger tire fit well. A friend builds up Enve m50 mountain rims for his disc road bike because they match well with 28-30mm tires. The overall profile is very smooth.

One of my favorite combos is the zipp 30 course with conti gp4000 28mm tires. Measure out to about 30mm and roll great while soaking up the bumps.
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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Slowman wrote:

4. almost 6 in 10 are choosing 23mm or thinner.

yes, there are aerodynamics to consider as well. is this your argument? or is there something wrong with my chain of reasoning above?

25mm tires rub my frame.
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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I own a few shops. We measure a lot of tires in order to know what will fit in frames. 23's can easily measure 25-26mm on certain rims. HOWEVER, people mainly buy 23s out of inertia and ignorance. Just FYI, I ran 24mm turbo cottons on a Jet disc and Enve front and they measure around 26. On Rovals they would be 26-27mm(and awesome). The new Tarmac and Emonda will accomodate 28-30s I bet.
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Re: Tire Width (I don't get it) [DDMike] [ In reply to ]
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DDMike wrote:
+1

on my Flo 60/90 wheels, 23 Conti GP4000 SII are far wider than 23... 25+ and there is just enough clearance on my 2015 Felt B series.

+1 Exactly my same set up.

Why? Why not? My engine has more potential for speed gains than my tire choice yet the potential is not reached.... that darn imperfect life thingy going on here. Not all is logical.

Hillary Trout
San Luis Obispo, CA

Your trip is short. Make the most of it.
https://www.slogoing.net/
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Re: Tire Width (I don't get it) [Tom A.] [ In reply to ]
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Tom A. wrote:
Slowman wrote:
Bonesbrigade wrote:
Most low crr 23mm tires test faster than 25mm tires when aero is factored in. Plus, many frames still do not fit wide rims with 25mm tires.


i'm not disputing you, but do you know this? how many tires have been tested on how many wheels? seems like there must be a lot of aero testing left undone in order to make a broad claim like this. if the 25mm tires on balance outroll their 23mm siblings, then the 23mm tires MUST perform better aerodynamically just to get back to even.


Here's one example of looking at that question:

http://bikeblather.blogspot.com/...t-3-after-party.html

Aero differences of the same tire models in different widths:


What happens when you factor in Crr:


As you can see, just looking at the SW Turbo models, the lower Crr of the 28C model isn't enough to overcome the better aerodynamics of the 26C and 24C models, which are basically "tied" out to 10 deg (BTW, the 22C model of that tire is a pretty huge outlier in regards to Crr for some reason, which is why it's excellent aerodynamics can't be taken advantage of).

Of course, those charts also show that the Turbo Cottons (both 26C and 24C models) outperform the rest due to their significantly lower Crr, despite worse drag at yaws greater than 5 degrees.

Looking at the graphs, for an example, the 0-yaw difference in the SW 22 and 24 look to be right around 0.19 versus 0.199, so let's call it a little less than 10% increase in drag. The difference in width is 9%. This makes me think that the change in Cd is pretty minimal for an aero bike wheel, so the loss in drag for a wider tire is about proportional to the increase in width. If I apply a rough guess of 30 watts Crr, then the wider tire needs to save ~3 watts in rolling resistance for every addition 2-3 mm in width. Seems like you would be lucky to find combinations where you were doing much more than break even. At some point the tire gets so wide you need a really deep airfoil >60-90mm.

I think I will stick with my SS20-H3/Jet disc TLR23 for now.
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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For me it's what will fit on individual bike. IRun Conti 25mm on my felt and 23 mm on my P3. The 25 on my P3 start to rub when they get heated up
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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23's barely fit on my P2 and Flo tires. I had a shop install them as I didn't know about the set screw in the drop out and they did a piss poor job...under side of my frame is rubbed to bare carbon after a ride in a light rain. I don't dare go any bigger and extend those set screws anymore as it doesn't look safe
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Re: Tire Width (I don't get it) [Tom A.] [ In reply to ]
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Tom A. wrote:
devashish_paul wrote:
Slowman wrote:
i can see now i asked the wrong question. the question i SHOULD have asked is what tire width you feel your next bike should accommodate. i will ask that in the next poll


If you could fit 28 mm on your bike and they had lower crr and just as aero as thin tires the only remaining reason to not race on 28mm would be rotational weight of the larger tire. Probably the only reason a 28mm tire or 32mm is less aero is the mate structure to rim, and rim depth. The other issue would be brake clearance and if your tire keeps getting bigger your overall wheel does so your gearing kind of changes.


And that's not even actually a legitimate reason...

For almost all riding the weight of the tire+tube (rotational weight) is not a concern, unless you are riding a crit or riding an uphill mountain stage finish with a lot of hairpins requiring accelerations. Then those would be the only use cases where the weight at the end of the rim kind of matters "a bit". What do you think?
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Re: Tire Width (I don't get it) [Slowman] [ In reply to ]
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25s rub on my bike... the rubber fin down the center of new GP4000s in 23 contacts the top of my brake flange. Some serious clearance issues on my bike.. front brake only.

I slapped a Red Aerolink on my bike before a race and it did rub my 23 tire for the entire race, rubbed a groove in the brake and was still rubbing... I'm beating a dead horse but its a clearance issue for me.
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Re: Tire Width (I don't get it) [gregk] [ In reply to ]
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gregk wrote:
One thing to consider is that wide-rim clinchers increase the effective tire size. For example, a 25mm-wide (external) / 21mm-wide (internal) Hed Plus rim makes a tire labeled 23mm inflate to about 25-26mm actual. So - is the poll asking about labeled size, or measured size when inflated?

This. Labeled tire widths are becoming less and less meaningful given the wide range of rim widths. Actual tire widths vary greatly depending on the internal width of the rim you mount them on. Add to that the fact that one manufacturer's "23mm" tire measures wider than another manufacturer's "23mm" tire and it really becomes a case where you need to know how a particular brand/size of Tire X will actually measure when mounted on a particular brand/internal width of Rim Y.

Mounted on my Bontrager Aeolus TLR wheels, the 23mm Schwalbe Pro One measures at >26mm. The outer rim width of the Aeolus wheels is 27mm. Applying the Rule of 105% to this 27mm rim width, that means I should not use a tire that measures wider than 25.7mm. So even running the "narrow" 23mm version of the tire, I'm really running a tire that is slightly too wide for these wide wheels.

Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
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