Diamante Pro radiale and a fish-tail issue - Cyclingnews Forum

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Old 12-07-12, 06:20
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Default Diamante Pro radiale and a fish-tail issue

Anyone using Vittoria's new radiale Diamante Pros? Or had a similar issue?

Feedback welcome, please...

I've had a pair since early August and put a few hundred k's on them, as well as racing on them.
I'm finding that the rear-end seems to "fish-tail" at speed. Most noticable when on the descents when beginning to pedal again. You know, when you discover you hadn't put it in a high enough gear and your cadence goes through the roof.
Once I feel the pressure on my feet again it seems to calm down, but I still need to push a high gear for it to settle, and even then I can still feel some movement of the rear wheel.
Have checked the frame for cracks in case that may be the cause, but everything appears to be sound...

Thoughts, ideas, experience...

[info that may matter: 2011 carbon frame, DT465 rims on ultegra hubs]
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Old 12-07-12, 13:48
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When that happens to me it's because of my pedaling technique....or lack thereof.

Of course you are suggesting that it doesn't happen with other tires so it appears as though that (pedaling smoothness) may not be your problem.
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Old 12-07-12, 14:13
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Quote:
Originally Posted by Archibald View Post
Anyone using Vittoria's new radiale Diamante Pros? Or had a similar issue?

Feedback welcome, please...

I've had a pair since early August and put a few hundred k's on them, as well as racing on them.
I'm finding that the rear-end seems to "fish-tail" at speed. Most noticable when on the descents when beginning to pedal again. You know, when you discover you hadn't put it in a high enough gear and your cadence goes through the roof.
Once I feel the pressure on my feet again it seems to calm down, but I still need to push a high gear for it to settle, and even then I can still feel some movement of the rear wheel.
Have checked the frame for cracks in case that may be the cause, but everything appears to be sound...

Thoughts, ideas, experience...

[info that may matter: 2011 carbon frame, DT465 rims on ultegra hubs]
Don't think it's the tires..Hub cones adjusted? Wheel true?

BUT put another tire on there to see if you 'feel' the same thing.
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Old 12-07-12, 14:42
winkybiker winkybiker is offline
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Might be a wheel balance issue caused by an out-of-spec tyre. The tyre may not be evenly seated on the rim. Have you tried switching to another tyre, or remounting that one?
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Old 12-08-12, 06:46
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worked just fine with the GP 4seasons I had on over winter, but will reseat and try a different tyre.

Could this be a possible explanation?
http://www.cycletechreview.com/2012/...e-tyre-review/
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Old 12-08-12, 23:31
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Quote:
Originally Posted by Archibald View Post
worked just fine with the GP 4seasons I had on over winter, but will reseat and try a different tyre.

Could this be a possible explanation?
http://www.cycletechreview.com/2012/...e-tyre-review/
Well you're riding them, how true is that review in your miles/k's on them?

As for the fish tailing, how are you positioned on the bike when it happens? Leaning forward, standing, sitting on the tip, sitting near the back, hovering on the seat?
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Old 12-09-12, 03:31
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Quote:
Originally Posted by Archibald View Post
............
Could this be a possible explanation?
http://www.cycletechreview.com/2012/...e-tyre-review/
This reviewer messed up his pressure conversions 60 psi is 4.1 bar, not 0.5 bar.

Anyway I read elsewhere that you have to match your tire and rim width for optimum performance.
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Old 12-09-12, 16:20
winkybiker winkybiker is offline
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Quote:
Originally Posted by Archibald View Post
worked just fine with the GP 4seasons I had on over winter, but will reseat and try a different tyre.

Could this be a possible explanation?
http://www.cycletechreview.com/2012/...e-tyre-review/
That seems a plausible explanation. Does it fit with your experience? I won't be buying a pair.
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  #9  
Old 12-10-12, 06:23
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Raced on them again this weekend after checking the fit.
pumped to just over 125psi.
really seemed to feel like the road was greasy under the rear wheel when pedalling at speed. Felt fine as soon as I stopped pedalling and freewheeled.

afterwards I asked my mates to take it for a spin to see if they felt it too, but all are on a different pedal system to me...

I did notice another bike in the bunch have some rear wheel movement of a similar nature during the race, but didn't mark him well enough to find him afterwards and question him. (I fell of the back with around 9kms to go)

Quote:
Originally Posted by ElChingon View Post
Well you're riding them, how true is that review in your miles/k's on them?

As for the fish tailing, how are you positioned on the bike when it happens? Leaning forward, standing, sitting on the tip, sitting near the back, hovering on the seat?
seated and can be either seated properly on the saddle or creeping forward on it. Usually leaning forward as you would for putting the hammer down.

Quote:
Originally Posted by winkybiker View Post
That seems a plausible explanation. Does it fit with your experience? I won't be buying a pair.
it kind-of fits...
I haven't noticed any cornering issues of under or oversteering. It never feels wrong when cornering, only when pedalling at speed when it feels like the road is "greasy" under the back wheel.
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Old 12-10-12, 10:03
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125 psi is kind of a high pressure for aussie roads; tires at high pressue tend to slip more often. Try at 100psi and see if still gives trouble. Learnt my lesson with Vittoria tires, Contis all the way for me.
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