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25c or 28c on wide rims?

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25c or 28c on wide rims?

Old 08-12-17, 03:47 PM
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25c or 28c on wide rims?

I had a local bike shop build me a new wheelset using the Boyd Altamont Lite rims. 19.5mm ID, 24.5mm OD. 23C tires measure more like 26-27mm on these but they seem to come much less tall.

I'm currently using my older 23C tires from when I had 15C inner diameter wheels. My current front tire (Michelin Pro4 SC 23C) measures 25.15mm wide and 21.41mm tall at 70PSI and the other (Conti GP4000S II 23C) measures 26.6mm wide and 22.79mm tall at 85PSI rear wheel.

Anyway, I picked up a few tires to test mount. Two Corsa G+'s at 28C and 25C and the newer Michelin power competition in 25C. In that order, and in width and height by mm, the tires measure 29.10 x 25.5mm, 27.28 x 23.7mm and 26.78 x 23.00 after letting them stretch for 48 hours starting at 75 PSI.

I'm thinking of picking up Schwalbe One's in 25 and 28 if the LBS has 28.

I've factored in deflection and my frame will not have issues running 28C tires at all which measure up to 30mm wide. I'll have 4mm+ on the sides and more on the tops.

If my priorities are more towards comfort and reliability but still would like good speed to hold on to wheels in fast group rides (38-40kph), which tire and size would you guys recommend I use? Thanks!
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Old 08-12-17, 04:02 PM
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Comfort and reliability would be better with tires of 28mm width (not anything 'C'). But at 40 km/hr air resistance is quite important and narrower tires have an edge there. Which wins out depends partly on the quality of your road surfaces.
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Old 08-13-17, 05:04 AM
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Really depend on how the roads are where you ride. I ride with 25mm Pro One's and like the way they feel but we also have nice smooth roads around here. 28's seem to be gaining popularity these days and tires are getting lighter so unless you're a pro trying to squeak out every last ounce of effort into your rides, I'd say go with comfort since your frame allows it.
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Old 08-13-17, 07:15 AM
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Originally Posted by prathmann
Comfort and reliability would be better with tires of 28mm width (not anything 'C'). But at 40 km/hr air resistance is quite important and narrower tires have an edge there. Which wins out depends partly on the quality of your road surfaces.
measured width, got it! Thanks! I considered aerodynamcis at those speeds. quite frankly, with a 25mm tall rim, i wasnt especting to be aero at all. and at those speeds, we're taking turns pulling (which is probably 60 seconds flat for me) then im back behind someone to draft.

the quality of the roads here is a mixed bag. some stretches are terrible and jarring. then some stretches have brand new asphalt.

Originally Posted by dvdslw
Really depend on how the roads are where you ride. I ride with 25mm Pro One's and like the way they feel but we also have nice smooth roads around here. 28's seem to be gaining popularity these days and tires are getting lighter so unless you're a pro trying to squeak out every last ounce of effort into your rides, I'd say go with comfort since your frame allows it.
thanks! cant find the pro one locally. just the none TL ones. I've been reading good things about them. i want to switch from conti's as mines all cut up on the sides that i can see thread under the rubber.

the roads here as mentioned above is quite an extreme mix of rough, smooth, so so, littered with gravel/glass... I'll aim to stay in the 26-27mm measured range. Thanks guys!
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Old 08-13-17, 07:55 AM
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Originally Posted by truflip
I had a local bike shop build me a new wheelset using the Boyd Altamont Lite rims. 19.5mm ID, 24.5mm OD. 23C tires measure more like 26-27mm on these but they seem to come much less tall.

I'm currently using my older 23C tires from when I had 15C inner diameter wheels. My current front tire (Michelin Pro4 SC 23C) measures 25.15mm wide and 21.41mm tall at 70PSI and the other (Conti GP4000S II 23C) measures 26.6mm wide and 22.79mm tall at 85PSI rear wheel.

Anyway, I picked up a few tires to test mount. Two Corsa G+'s at 28C and 25C and the newer Michelin power competition in 25C. In that order, and in width and height by mm, the tires measure 29.10 x 25.5mm, 27.28 x 23.7mm and 26.78 x 23.00 after letting them stretch for 48 hours starting at 75 PSI.

I'm thinking of picking up Schwalbe One's in 25 and 28 if the LBS has 28.

I've factored in deflection and my frame will not have issues running 28C tires at all which measure up to 30mm wide. I'll have 4mm+ on the sides and more on the tops.

If my priorities are more towards comfort and reliability but still would like good speed to hold on to wheels in fast group rides (38-40kph), which tire and size would you guys recommend I use? Thanks!
How do you run such low pressures...70 psi F 85 psi R without pinch flatting? Are you light?...running tubeless?


Unless roads are rough, stick with 25c would be my suggestion for 40 kph group rides. Aerodynamics and weight are the downside of 28c. For slower speed or less aggressive riding, 28c makes a lot of sense. I have them on one bike and I really like them...25c on my fast group ride bike so I can keep up.
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Old 08-13-17, 10:41 AM
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Originally Posted by Campag4life
How do you run such low pressures...70 psi F 85 psi R without pinch flatting? Are you light?...running tubeless?
I haven't gone above 90psi in years, often lower if I have a 25 or 28. Once I wear out my stock of tires I'm only using 28 save for race wheels (where the tire size will be matched to the rim profile) and I'll try to run them at 60-75psi. I weigh between 180-190 lb, and use lightweight tubes on road. Every puncture I've had in the last several years has been foreign object related save one or two.
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Old 08-13-17, 01:15 PM
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I run my 25mm clincher tires at 85psi all the time...often 80 in the front. I weight 160lbs. I've had no problems with speed retention or pinch flats.

If I take my 30mm tires off-road, I'll lower then to 35psi with no problems...feels a bit soft in tarmac, but off-road it's comfy.
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Old 08-13-17, 04:40 PM
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winter 28mm is the way to go
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Old 08-13-17, 05:23 PM
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Originally Posted by Campag4life
How do you run such low pressures...70 psi F 85 psi R without pinch flatting? Are you light?...running tubeless?


Unless roads are rough, stick with 25c would be my suggestion for 40 kph group rides. Aerodynamics and weight are the downside of 28c. For slower speed or less aggressive riding, 28c makes a lot of sense. I have them on one bike and I really like them...25c on my fast group ride bike so I can keep up.
Hahah ya I'm 143#. No pinch flats yet. Running regular tunes.

Ok I will stick with 25c. Thanks for your input!
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Old 08-13-17, 05:54 PM
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Originally Posted by Campag4life
How do you run such low pressures...70 psi F 85 psi R without pinch flatting? Are you light?...running tubeless?
Yep, I'm with the others only heavier. I've been running at 189 to 193 lbs all year. I run 80/90 FR on all my bikes that have GP 4000sII 700 x 25 tires. From some really narrow vintage rims to the wider Pacenti SL23's. One pinch flat in during easily over 10,000 miles and I ride really bad chipseal primarily. I even hammered the worse section last week while running over 29 mph for a KOM on a Strava section. It's was a .9 section that is in really bad shape. Cracked, pot-holed, frost heaved, broken, sorry excuse for even bad chipseal. I probably grabbed this KOM because my steel bike really soaked up the surface. This is the section I rode a Domane on a couple of years ago and realized they still weren't there yet. Hmm, maybe time to try a new model Domane.... Nah!!

My pinchflat happened on a really fast turn where the back sidewall caught a rock that I didn't avoid well enough.
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Old 08-13-17, 06:53 PM
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I've been happy with the 700x28 Vittoria Corsa G+ on my De Rosa. It provides both low rolling resistance and a plush ride. I've had one flat this year, that's normal on the roads I frequent.

Review this for guidance on size: https://www.bicyclerollingresistance....0s-ii-23-25-28

"The bigger the tire, the lower the rolling resistance at the same air pressure. When you run lower air pressures, the differences get even bigger. At a comfortable 80 psi, you're only giving up 2-3 watts for a pair of tires when going for the 28C size. That's good to know when you decide to go for a bigger tire because you like a more comfortable ride or ride on bad roads with potholes a lot.

Off-course, what will be won in the rolling resistance department, will be lost in the aerodynamics department. I'm not sure at what kind of speed this turnover point would be. This also depends greatly on the tire/wheel combo. A 28C tire on a rim that is designed for a 23C tire will perform poorer".
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Old 08-14-17, 04:26 AM
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Originally Posted by jamesdak
Yep, I'm with the others only heavier. I've been running at 189 to 193 lbs all year. I run 80/90 FR on all my bikes that have GP 4000sII 700 x 25 tires. From some really narrow vintage rims to the wider Pacenti SL23's. One pinch flat in during easily over 10,000 miles and I ride really bad chipseal primarily. I even hammered the worse section last week while running over 29 mph for a KOM on a Strava section. It's was a .9 section that is in really bad shape. Cracked, pot-holed, frost heaved, broken, sorry excuse for even bad chipseal. I probably grabbed this KOM because my steel bike really soaked up the surface. This is the section I rode a Domane on a couple of years ago and realized they still weren't there yet. Hmm, maybe time to try a new model Domane.... Nah!!

My pinchflat happened on a really fast turn where the back sidewall caught a rock that I didn't avoid well enough.
Thanks for your comments and to others that seem to be in the 180 lb range and run well under 100 psi with 25c.
My current riding weight is about 180 lbs or a bit less and I generally run 100 psi rear and 95 psi front...or about.


Sounds like many of you guys run less pressure...perhaps to a surprising level.


Other thing is...makes sense to ride less pressure as you do if you ride the bumpy stuff like chipseal. And if I were you, I wouldn't change to a Domane either if you can achieve KOM's riding 29 mph over rough road on steel. All about the engine and yours sounds strong. Well done
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Old 08-14-17, 04:33 AM
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Originally Posted by Barrettscv
I've been happy with the 700x28 Vittoria Corsa G+ on my De Rosa. It provides both low rolling resistance and a plush ride. I've had one flat this year, that's normal on the roads I frequent.

Review this for guidance on size: Continental Grand Prix 4000S II 23 25 28 mm Comparison

"The bigger the tire, the lower the rolling resistance at the same air pressure. When you run lower air pressures, the differences get even bigger. At a comfortable 80 psi, you're only giving up 2-3 watts for a pair of tires when going for the 28C size. That's good to know when you decide to go for a bigger tire because you like a more comfortable ride or ride on bad roads with potholes a lot.

Off-course, what will be won in the rolling resistance department, will be lost in the aerodynamics department. I'm not sure at what kind of speed this turnover point would be. This also depends greatly on the tire/wheel combo. A 28C tire on a rim that is designed for a 23C tire will perform poorer".
I believe...depending on how poor the roads are, aerodynamics trumps reduction in rolling resistance and why for fast group rides 25's get the nod over 28. But and this is important, depends on how bad the roads are. If riding rough road, rolling resistance difference is more...28c becomes much more attractive. Less speed is abated by the bumps. But for smooth roads for most 25c wins the day for many I believe. And then there is the weight of the tires for spool up like fast accelerations. But no doubt the aerodymamics/rolling resistance curves converge if riding roads bad enough...say in a Classic race with cobbles like the Paris Roubaix where some run as wide as 30c and very low pressure to reduce the sting of 30 mph foray's over rough roads among the strongest riders. But we aren't the strongest and don't ride uber high speeds as a rule and so a bit wider makes sense. No question 28c is more comfy to back and neck and wrists and all the places affected by riding bent over for hours.

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Old 08-14-17, 05:30 AM
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Originally Posted by Campag4life
I believe...depending on how poor the roads are, aerodynamics trumps reduction in rolling resistance and why for fast group rides 25's get the nod over 28. But and this is important, depends on how bad the roads are. If riding rough road, rolling resistance difference is more...28c becomes much more attractive. Less speed is abated by the bumps. But for smooth roads for most 25c wins the day for many I believe. And then there is the weight of the tires for spool up like fast accelerations. But no doubt the aerodymamics/rolling resistance curves converge if riding roads bad enough...say in a Classic race with cobbles like the Paris Roubaix where some run as wide as 30c and very low pressure to reduce the sting of 30 mph foray's over rough roads among the strongest riders. But we aren't the strongest and don't ride uber high speeds as a rule and so a bit wider makes sense. No question 28c is more comfy to back and neck and wrists and all the places affected by riding bent over for hours.
Well said and an important point. I'm in the wider-is-better camp, especially on longer rides over rural chipseal roads. However, I've reinstalled my smaller lightweight tires on raceday, as they are more efficient when I average 21 mph or faster. At 25mph, while in time-trial mode, the smaller tire needs significantly less power to maintain speed.
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Last edited by Barrettscv; 08-14-17 at 06:13 AM.
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Old 08-14-17, 10:17 AM
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The Schwalbe One 28's are some amazing rubber, i run the older kind prior to V-Guard too. They roll super nice.

They run more like 30c on my Zonda C17's , but i ride my TCR confidently thru some garbage pavement and cobbles, heck they go over river rock pretty good too for a race tire on a race bike. 4 months and about 700 miles, no flats nor what felt like close calls, even catching the shasp mouth of those recessed gas lines they leave on newly paved road these days.. They dont complain.

My BMC sadly can't fit them, or i'd run them on there too.

As far as speed and drag, frankly i ride both bikes off and on during the week and my avg speed on my Strava rides are consistent whether riding those 28c's or the 26c Specialized Turbo Pro's on the BMC.

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Old 08-20-17, 09:48 PM
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Thanks everyone. I decided to get a second Michelin PowComp 25C. on my Altamont Lite wheels, they measure 26.78mm wide and 23mm tall. Ran them today at 70PSI front and 85PSI back. Pretty sweet so far on some of the rougher roads.
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