Colnago C60 rear tyre clearance

[wedgie]

I have a C60 with the newer wide Campagnolo Boras. I like to ride 25mm Continental GP4000 tyres, but vertical clearance at the rear brake bridge is only about 2mm. Front clearance is better, about 3mm.
When i change to 23mm GP4000s, clearance is obviously much better - closer to 4mm on the rear, almost 5mm on the front.
The problem with so little clearance on the rear with 25mm tyres is potential damage to the underside of the brake bridge. I'm not bothered about paintwork, more concerned with structural damage caused by stones and debris, particularly in the wet.
Is 2mm clearance enough or should I run the 23mm tyres? Any C60 owners running 25mm tyres? Any brake bridge damage?!

[Mr.Gib]

IMO 2 mm is not enough clearance at the top of the tire and only the bare minimum acceptable side clearance (at the chainstays).

2 mm is fine until it is not fine - tire heats up, stretches, chunk of tar and gravel adheres, wheel goes out of true, etc. If this is a strictly fair-weather bike that you will ride on good roads in your home area, then the risk is minimal. If you plan on anything more epic it might not work out so well.

Structural damage is not really a factor - paint will suffer. Having a wheel jam from an unlucky piece of gravel is always a minor but real risk.

Love these bikes, but tire clearance is the fly in the ointment for me. I bet future versions will provide more room.

[fa63]

Continental tires run on the fat side. If you want a more true to size 25 mm tire (even with wide rims), take a look at the Veloflex Corsa. They ride very nice too.

[Calnago]

I have a C60, and run 25mm tubulars (Veloflex Arrenbergs, Conti Comps) on the new Boras. No issues, lots of clearance. However, when you start talking clinchers it's a lot less cut and dry because the end result is a function of how wide a rim you are putting them on. For instance the Conti 4000Sii is about as tall a sitting tire as I've come across so it's always my standard goto test mule when checking clearances. On the new Campy Shamal Ultra, with it's wider 17mm internal width (which should be same as the Bora clinchers), a 25mm Conti 4000sii plumps up to 27mm wide. It's pretty big. There's enough clearance on the C60 to run that; as you say it's about 2mm and that would be my limit for sure. And no, you're not going to cause any structural damage to the brake bridge. I found that running with less than 2mm clearance (C59 for example) would cause annoying chatter sometimes if there was small grit on the road which would stick to the tire and get thrown through the front fork. But with the new Boras, the same tubular tire sits just that little bit more lower in the rim bed (designed for it) and that little extra clearance is all that was needed to eliminate that annoyance altogether, even in my C59 and EPQ, which shares the same fork and stays as the C59. So, my guideline is a clearance of 2mm for nice chatter free road cycling. I've known guys to run with less than that, but it's very very tight and like I said, just plain annoying. There is loads of chainstay and seatstay clearance so that will never be an issue even if your wheel does go out of true.

Here's some fresh pics of:
1) a 23mm Conti 4000sii clincher on a Campy Shamal Ultra 17mm internal width in the C60 rear (interesting that it ends up being about the same size as a Veloflex Arrenberg 25mm tubular on a new Bora rim)...



2) a 25mm Conti 4000Sii clincher on the same rim (Campy Shamal Ultra 17mm internal width)...



3) Veloflex Arrenberg Tubular (25mm) on a Campy Bora Ultra (newest profile) rim...


So, in conclusion, a 23mm Conti 4000sii clincher on the newer Campy rims will end up being about the same size as 25mm tubular.
Personally, I wouldn't run anything bigger in a tubular on the road as it starts feeling "spongy" versus "firm" on the road. With clinchers you just have to experiment and decide which you like the feel of best.

[Lukester]

After reading the OP's inquiry I thought it best to check mine. On my C59 I'm running Lightweight Clinchers, (20 mm) with 25" Conti 4000s2 and barely have 2 mm. The front 'appears' to have even less clearance, like a piece of paper clearance! And I'm not flyweight at 190lbs which doesn't help the issue. Obviously I need to change tires. Understand the Conti's are tall but are the others such as Veloflex shallow enough to give me proper clearance or should I go with 23's to be safe?

[AJS914]

I'd seen this on more than one used C59s. Best to stick with under 25mm (actual size) and as stated GP4000s run large.

[Lukester]

That ain't good! Hard to believe they rode with virtually no clearance! With these stiff Lightweight wheels I was hoping for just a bit more comfort but maybe its not in the cards? I just ordered a set of Veloflex Corsa 23's and 25's. To be continued....

[Mockenrue]

I put strips of thin electrical tape under the fork crown and brake bridge. They stop debris from ruining the paint like this.

[showdown]

I'm running vitroria corsa 27mm with ultegra wheels on my c60 without any issues. I also run conti 25mm clinchers without issue and veloflex 25mm on my mavic CCUs with plenty of space.

[asdf123]

I'm running vitroria corsa 27mm with ultegra wheels on my c60 without any issues. I also run conti 25mm clinchers without issue and veloflex 25mm on my mavic CCUs with plenty of space.

27mm ? They make that?

[Lukester]

As Calnogo stated its all a function of the rim width and of course the frame it's going on as they're all not created equally. Thanks for all te comments!

[showdown]

My bad, I meant the Vittoria Open Pave EVO CG III...

But yeah, they come in 27mm and fit into the C60. I'm sure some will decry the tight tolerances and point to the photos of wear under the fork etc.. Frankly, I don't really care if my bike gets chipped or paint gets damaged. I race the hell out of it and if it get's worn then so be it. Then again, I have long since passed the point of treasuring bikes- they're tools and should be used until they can no longer meet their purpose... but then again, I suspect that I'm in the minority as many cherish their bikes to the point of fetishism, and that's ok too.

[scb]

On my C60, I am using 25mm Vittoria Corsa G+ clinchers on my Bora Ultra 35s with enough clearance and no issues whatsover.

[fa63]

What size frame?

[scb]

What size frame?

57 traditional