c40 tyre clearance

[bontie]

Am I doing something stupid? It seems as if my Colnago C40 does not have enough clearance to run 25mm tyres?
After having sliced two Michelin tyres in a fortnight I got Continental Gatorskins in 25mm in the hope that they would last longer, and it seems I stuffed up

[SalsaLover]

What Michelin version ?

Pro Race 2 25mm fit more like 28s, I was able to fit a set of those on a C40 but had to re dish the rear wheel.

[bontie]

Sorry if I was unclear - I had Michelin 23mm and they fit fine, but my 55km per day commute didn't play well with them. The roads aren't the best around here...

Pardon my stupidity but what does "redish" the wheels mean?

PS - I deflated the tyre to about 6bar and it seems to fit now. I am however still reluctant to ride like that...as there is VERY little clearance

[SalsaLover]

Re dish, is to alter the wheel centering in the seat stays or fork for a better tyre fit.

Sometimes a slim tyre would not touch the seat stays even when the wheel is not properly centred ( or dished ) , for larger tyres you would need to centre it better

[bontie]

Ahh, makes sense. Funny thing is the tyre seems to touch on the brake bridge i.e. it is almost as if the circumference of the tyre is > stays...

[em3]

Redishing your wheel in order to make a wider tire fit is a poor, and more importantly, nonsensical idea that should NOT be followed . If you have to redish your wheel to get a wider tire to fit your frame that means your wheel was out of dish to begin with. Tire clearance issues are linked to vertical clearance (under your fork crown or under your brake caliper) and rarely liked to horizontal clearance. EM3

[bontie]

Correct, as stated above the tyre rub above, the wheels are factory built Campy wheels, no re dihing required.
Pressure down to 7 and the clear now (only just!)

I just found it strange that the 25mm tyres would not fit?

I have the tyres now, may need to get a new frame to fit

[tabmaster]

No need for a new frame. Ebay the 25mm Contis and spend the money on a pair of Vittoria Pave 24mm's. I run them on my C50.

Paul.

[ElDuderino]

i ran 700x25 michelin carbons, no issues.

[juanacity]

Putting 25mm Conti GP4000S tires on my bike is the single best improvement I have made for performance/comfort. I am a big fan of 25mm tires in general.

If I understand correctly, the clearance through the stays/fork isn't the issue, but vertical clearance to the caliper arms. I had a similar issue and just switched out for new brakes that had more clearance.

[andyindo]

Bontie...What you should do is buy some decent alu tubs like ambrosio nemesis and put some veloflex paves on them. That'll really give you a comfortable ride, is puncture resistant and will suit the stature of a Colnago C40.
Do the right thing here....

[bontie]

Putting 25mm Conti GP4000S tires on my bike is the single best improvement I have made for performance/comfort. I am a big fan of 25mm tires in general.

If I understand correctly, the clearance through the stays/fork isn't the issue, but vertical clearance to the caliper arms. I had a similar issue and just switched out for new brakes that had more clearance.

No the clearance to the fork bridge is too tight (as if the stays are too short) - it is a size 54. It clears the calipers by miles.
Mind you the one tyre is slightly worn, and that seems fine. SO maybe I should just wear the other one down.

[bontie]

Bontie...What you should do is buy some decent alu tubs like ambrosio nemesis and put some veloflex paves on them. That'll really give you a comfortable ride, is puncture resistant and will suit the stature of a Colnago C40.
Do the right thing here....

Yes, tubbies would be the perfect solution. The roads around Heathrow would definitely play nice with tubbies at £55+ a pop. Let alone gluing tyres next to the road in the dark days during winter... I think I'll just get a new frame.

[c50jim]

I'd play around with tires a bit more before replacing the frame. I've tried a dozen or more other frames since my first C40 in 1995 and keep coming back the the C40. I even found a couple of NOS ones last year. It would be hard to duplicate the C40 mired with a new bike, although you can duplicate the handling with a new, stiff Colnago.

Rather than worry about tire size, I'd worry about durability. I've had good luck with Michelins lately but not always in the past. If the Gatorskins are working, why not just go to 23? It sounds as though you can wear out the 25 on the back.

[bontie]

Thanks C50jim, I am going to give it a go with the Gatorskins - at 6 bar front it is not touching, so I will see how that goes.
As for a new frame, everyone needs an excuse to get another bike, not true

I know what you mean that you keep coming back to the C40...