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Discussion Starter · #1 ·
Bianchi Infinito CV, dura ace 9000 calipers, 28mm gp 4000s barely fit with wide rimmed wheels.

How little tire clearance are you comfortable running? The 28s fit by a millimeter, maybe 2mm on all sides... Is that too little? They roll just fine in my garage no rubbing at all but I can't help thinking that if I light up a sprint I'll come to a dead stop suddenly from the wheel flexing and a tire catching on the caliper... Am I being too cautious or should I just ride them? Crit tonight and I want to ride but I want to be safe about it.
 

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1mm between what? The brakes or the chain stays? That is VERY little clearance.

I doubt you will come to a dead stop, but any flexing will cause rubbing. This is great if you are looking for progressive resistance, but not so great for your frame or tires.

But seriously, you're thinking of Christening these things on a crit? You really should debug new equipment elsewhere. Just my two cents.
 

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Discussion Starter · #3 ·
It's probably 2mm of clearance on all sides of the tire and the brakes, frame has plenty of room to play with.. I think I had the same reaction as you (I'll try spinning around the block tonight and see how it goes), more curious now about how much clearance most people are comfortable with.

A little surprising for me I thought 9000 brakes would have plenty of room..

Edit: I have old 25s I'll throw back on for tonight.
 

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It's probably 2mm of clearance on all sides of the tire and the brakes, frame has plenty of room to play with.. I think I had the same reaction as you (I'll try spinning around the block tonight and see how it goes), more curious now about how much clearance most people are comfortable with.

A little surprising for me I thought 9000 brakes would have plenty of room..

Edit: I have old 25s I'll throw back on for tonight.

What were your old brakes? 2mm still seems narrow, but depending how stiff your wheels are, it might fly. However, there is no room for trueing error here.

One test you could do sometime is mash up a steep hill and see if you get any rubbing.
 

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Discussion Starter · #5 ·
No old brakes, normally just ran 25s, picked up 28s on a whim. Do ride a wide rim wheel too which I think is probably the source of my trouble, if I rode mavic open pros I think I'd be just fine..
 

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The word is wide wheels, I'm sure your 28's are actually at least 30. I know my 4 season 25's when measured on Pacenti SL23V2 wheels, are actually and checked with calipers are over 28, like 28.4 or so. On that bike the clearance on the fork was very close, I rode it some didn't notice rubing, but have since replaced them with a set of GP400S2 tires in a 23 size, and they actually measure about 25.4, and fit better. My 28mm Specialized tires on HED Belgium + wheels are actually a little more than 30mm and I have them on my rain/slower training cross check.
Adam
 

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No old brakes, normally just ran 25s, picked up 28s on a whim. Do ride a wide rim wheel too which I think is probably the source of my trouble, if I rode mavic open pros I think I'd be just fine..
I just built up a set of HED C2s. They are 17.5mm compared to my 15mm Shimano factory wheels. I normally ride 28c tires and thought clearance might be an issue. Tire width increased less than 1mm, so I have effectively 29c tires instead of 28c. Still enough clearance and since these wheels are stiffer, less flex anyway, so a non-issue.

I would pass on Mavic Open Pros. If you search around on this forum, you will see there aren't a lot of good opinions on those. Not sure what wheels you are riding now, but if you want a narrower wheel to be able to use 28c tires, there are other choices. I believe DT Swiss still makes some decent 15mm rims.
 

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Conti GP4000S in 28 measure about 30mm on narrow rims and up to 32 on wide rims. I've got a set on my CX bike for old logging roads. They are not a tire I'd ever mount up on my dedicated road bike.
 

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@wradom

No set rules on clearance other than common sense. IMO, 3-5 mm clearance all around is the minimum I try to have.
 

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Bianchi Infinito CV, dura ace 9000 calipers, 28mm gp 4000s barely fit with wide rimmed wheels.

How little tire clearance are you comfortable running? The 28s fit by a millimeter, maybe 2mm on all sides... Is that too little? They roll just fine in my garage no rubbing at all but I can't help thinking that if I light up a sprint I'll come to a dead stop suddenly from the wheel flexing and a tire catching on the caliper... Am I being too cautious or should I just ride them? Crit tonight and I want to ride but I want to be safe about it.
You might or might not get rub due to wheel flex. What I would worry about much more would be some sort of road grit getting picked up by the tire and jammed between the tire and frame. Significant scratching would be the minimum result.
 

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It's probably 2mm of clearance on all sides of the tire and the brakes, frame has plenty of room to play with...
I wouldn't worry about that (unless you get rub when standing.) If you get a slightly out of true wheel you can just open up brakes and get home okay. Cutting it really close on a frame, especially a carbon one, is where you should have more room to allow for routine out of true wheels.
 

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You might or might not get rub due to wheel flex. What I would worry about much more would be some sort of road grit getting picked up by the tire and jammed between the tire and frame. Significant scratching would be the minimum result.
Don't get much truer than this.

Enough road debris jammed in those close clearances could cause significantly more than scratches, IE, face plant.
 

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Bianchi Infinito CV, dura ace 9000 calipers, 28mm gp 4000s barely fit with wide rimmed wheels.

How little tire clearance are you comfortable running? The 28s fit by a millimeter, maybe 2mm on all sides... Is that too little? They roll just fine in my garage no rubbing at all but I can't help thinking that if I light up a sprint I'll come to a dead stop suddenly from the wheel flexing and a tire catching on the caliper... Am I being too cautious or should I just ride them? Crit tonight and I want to ride but I want to be safe about it.
You need at least 4 mm both sides and at the top.

Sure you can get away with 2 mm on perfect roads and on the flat. I wouldn't do any descending with 2 mm clearance.

I know Continental tyres are expensive. But why not mounting new 25 mm tyres on your wide rims? 25 mm tyres on a wide rim are still bigger in volume than 25 mm tyres on standard 15c internal width rims.
 

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I have only 2 mm clearance between my tire sidewall and my left chainstay when running 25 mm tires on my 17c rim. Everywhere else is about 4 mm. No scuffing of the inside chainstay so I assume no tire rub when the wheel flexes while sprinting or climbing.


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I have only 2 mm clearance between my tire sidewall and my left chainstay when running 25 mm tires on my 17c rim. Everywhere else is about 4 mm. No scuffing of the inside chainstay so I assume no tire rub when the wheel flexes while sprinting or climbing.


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Only narrow clearance on the LEFT chainstay? Sounds like the wheel wasn't dished correctly.
 

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I tried flipping the rear wheel to see if the narrow clearance switched from the LEFT to the RIGHT chainstay. It did not, so I must conclude that the wheel is dished properly and instead the frame has asymmetric chainstays. Plus all three of my wheels (Bora One 35 Clincher, Bora One 50 Tubular, and Shamal Ultra Clincher) have less frame clearance on the left chainstay than the right.


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