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Post by Deleted on Aug 1, 2013 20:41:35 GMT
Took the T5A out for a ride this evening, only to get 100m down the road and the front tyre suddenly went flat Thankfully it happened straight away so was a short walk home rather than having to repair at the roadside. Upon inspection I found 2 small holes, according to some google results the 2 holes together would suggest it was a pinch flat (must've hit a stone, there were no potholes or bumps). Now admittedly it has been about half a week since I bought the bike, and I have no idea what pressure they inflated the tyres too so they were likely slightly under inflated, going to go out and buy a floor pump with pressure gauge tomorrow to keep them inflated at correct pressure. Are pinch flats just something I am going to suffer with until I lose weight (currently 18st) or will it just have been a low pressure resulting in the flat? or with the weight would it be wise to get 25mm tyres? Also going to get some spare tubes while I'm in halfords tomorrow, I'm thinking it's probably better to go for something like continental tubes rather than halfords.
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Post by Deleted on Aug 1, 2013 20:46:51 GMT
I tend to run my 23's at about 110-115 psi and not had a pinch. Wouldn't like to say if you can run 25's as high. I got some tubes from Planet X. 5 for 12.99,
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Post by martin122 on Aug 1, 2013 20:49:42 GMT
I run my 23 at 120psi and never had a problem
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Post by zoltansocrates on Aug 1, 2013 20:51:45 GMT
if you are 18 stone id suggest pinches are inevitable on even smaller holes, dont be offended by that but its a mixture of the tyre not being hard enough and the shape the innertube with your weight bearing down on it
be prepared to true your back wheel a bit more regularly too, unfortunately
stick with it though, the pounds will fly off once you get a head of steam up , goodluck
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Post by Deleted on Aug 1, 2013 20:55:30 GMT
I'm a 10 stone weed and I have had pinch flats..... Just keep your eyes on the tyre pressure and dodge those pesky potholes.
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Post by Deleted on Aug 1, 2013 20:59:53 GMT
blimey that was quick, the tyres say max 110psi so will try running them around 110-120 and see how it goes.
Wasn't expecting it to be perfect with my weight on the tiny tires, but I was hoping for more than 100m, guess I was unlucky.
Will have a look at planet-x for tubes, thanks
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Post by Jonnie W on Aug 1, 2013 22:14:42 GMT
Road tires/tubes tend to loose air pressure pretty quick so it's a good idea to check the pressure before you go out, in my experience anyway.
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Post by Deleted on Aug 2, 2013 8:35:57 GMT
At 18 stone (252 pounds) you ideally need the following tyre pressures:
Use the following formulas to determine proper tire pressure as a function of rider weight and tire section:
Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33 Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33 Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33 Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33 Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67 Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67 Front Pressure = .9*Rear Pressure
For example, the OP weighs 252 lbs and uses 23mm wide tires, so Rear Tire Pressure = 0.33 x 252 + 53.33 = 136 psi. Front Tire Pressure = 0.9 x 133 = 122 psi.
This is the rule of thumb I use, but my tyres (Schwalbe Luganos) only go up to 110 PSI so I run them at that. Tend to pump them up once a week as they lose a fair bit.
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Post by Deleted on Aug 2, 2013 10:24:12 GMT
Thanks for that table, very helpful. Tyres say max 110 PSI so will try keeping them at that and see how things go.
Tempted to get something like 25c gatorskins as they have a max 120 PSI and from the above table I should then be able to get very close to the proper pressure, as well as being more puncture resistant.
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Post by Deleted on Aug 2, 2013 10:25:45 GMT
I run the stock T3a tubes and tyres at 110. No flats yet but it's only a matter of time!
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Post by chas on Aug 2, 2013 11:00:33 GMT
I'd suggest trying some Vittoria Zaffiro's in 25mm (they tend to be a bit bigger than they say) much cheaper than Gatorskins and take higher pressures (145psi for 23s)
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Post by Deleted on Aug 2, 2013 11:12:04 GMT
Thanks for that table, very helpful. Tyres say max 110 PSI so will try keeping them at that and see how things go. Yeah according to my weight and that table I should have rear at 130PSI, but as I said my tyres are only rated to 110 so stick to that. I've done 666 miles now according to strava and so far not had a puncture, although I expect to get one today now I've just jinxed myself.
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Post by Deleted on Aug 2, 2013 11:13:53 GMT
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Post by chas on Aug 2, 2013 12:33:06 GMT
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Post by Deleted on Aug 2, 2013 15:35:56 GMT
Bought a floor pump today, rear was sitting at around 50 PSI, must've not been inflated much at decathlon and then after a few days to deflate not much air left in them. Went for a ride on 110 PSI and no problems whatsoever (except sore legs!)
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