My first DNF!

dttlincs

Only on my 6th 10 mile TT tonight. PB so far 27.44. This was a different course to previous and a bit rolling and some of the road a bit damp from previous rain.
Anyway half way round I was going well, catching a clubmate who is normally faster than me. A series of 3 downhill 90 degree bends, first two I got round OK but on the third I drifted to the outside of the road and had a front tyre blow out and ended on the verge. Kept it upright but the tyre is a write of along with the tube.
Obviously I should have took the corner slower but I also have a feeling that the Specialized Pro Mondo tyres are poor in the wet and contributed to things. Anyone else found this?
I will be replacing with something else! But what?

cougie

Your tyre blew when you ran off the road and hit the kerb ? Sounds to me like you were just going too fast for the conditions ?

Did you lower your tyre pressure for the rain ? There may be nothing wrong with the grip on the tyres - more the way that you were riding ?

I like the GP4000s tyres - but if you go into corners too fast - you cant rely on your tyres to get you out of the situation.

brownbosh

I doesnt say his tyre blew when he hit the curb. It says he had a blow out then went over the verge. There is no accounting for a blow out. You may have been taking a shoddy line, not going too fast! Most effient riding lines differ from a closed circuit to an open road and the entry and exit points need to be calculated according to these factors, the weather, your skill and the tightness of the limit point of the bend. A skilled tester may well have got through far quicker without issue.

dttlincs

Cougie -First thanks for the reply! I may have been going too fast but not having seen the course before I do not Know! There were 3 of us about 5 to 10 metres apart. We were 1/2 way round and I had just been overtaken by the guy behind me prior to the corners(an experienced rider) and then further on was the guy who I was catching who started just before me(30 second intervals last night). They both got around fine and I was taking a similar line/speed as them prior to the blow out. I was making a conscious effort on this 3rd of 3 corners as I didn't think I had taken the previous 2 that well.
There was not a kerb. It is a country course, tarmac road which drops off a few inches from the edge of the road to the grass verge.
On closer inspection of the tyre today I had one big rip in it about 1 inch long and 1/2 inch down on the sidewall. I think that was probably done as I left the road, on the edge of the tarmac. There was also another 1 inch long cut on the same side 1/2 way round. The tube only had 1 cut about an inch long though.
Brownbosh - Thanks for the reply and a bit of support!
I will be riding the course again in a couple of weeks.
**Lastly as was riding number 13! Is it right you can wear this unlucky number upside down??? I wasn't!!

cougie

Blow outs are very very rare. There is usually a reason -so in this one it was the edge of the tarmac that knackered the tyre and blew it out. What pressure did you have in your tyres ? I let mine down a tad if its wet.

dttlincs

Tyre pressure at 100psi ish. New to TT so lesson learnt there! If it had been 2 weeks ago I would not have had my nice new track pump to get the Psi up! I think prior to that I was only at 60/70psi.
Any more tips for dry vs wet TTing?
Thanks

brownbosh

I never let my pressures down. I change approach and leaving lines and breaking technique. You should not be moved off line in a hurry in a TT so it is simply a matter of timing. Blow outs do happen but good quality tyres tubes and rim tape will help prevent them.

cougie

I think about 100 is the max you should use. Try 90 next time you're out in the wet ?

brownbosh

cougie wrote:

I think about 100 is the max you should use. Try 90 next time you're out in the wet ?

???
My normal road bike tyres - 120 psi.
Race and TT bikes - 140 psi.

If i left a tyre at 90 it would roll off...

Bhima

dttlincs wrote:

Specialized Pro Mondo tyres

Oh god.

Mate, they're the WORST tyres i've ever ridden on! They came on the crappy Alex Rims wheels which came with my bike when I bought it.

I got some amazing Mavics but only recently replaced the tyres for some 20mms which are absolutely impossible to get on/off the rim, but anything is better than those Pro Mondos!

The 20mm tyres I have are some red, unbranded puncture-proof things so not exactly race-standard, but I immediately felt a massive drop in rolling-resistance and can go round corners much better now!

Pro Mondos are terrible!

[Rant Over]

eh

Going too fast won't cause a blow out, but a split on the sidewall suggests the brakes may have been rubbing the sidewall. Did you touch the brake on entry to the corner?

If i left a tyre at 90 it would roll off...

Bullsh*t, 90psi is a sensible tyre pressure for 700x23 tyres in the wet.

brownbosh

eh wrote:

Going too fast won't cause a blow out, but a split on the sidewall suggests the brakes may have been rubbing the sidewall. Did you touch the brake on entry to the corner?

If i left a tyre at 90 it would roll off...

Bullsh*t, 90psi is a sensible tyre pressure for 700x23 tyres in the wet.

No doubt you are a tiny pencil neck. My statement says 'IF I LEFT A...'. But thank you for your comment.

cougie

140 waaay too high. Been there, tried it, and now I've seen the light !

I was bouncing all over the place at those kind of pressures - and I used to flat more.

brownbosh wrote:

cougie wrote:

I think about 100 is the max you should use. Try 90 next time you're out in the wet ?

???
My normal road bike tyres - 120 psi.
Race and TT bikes - 140 psi.

If i left a tyre at 90 it would roll off...

I dont understand your tyre rolling off at 90 ???