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Kevlar Tyre liners

 
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dr dre




Joined: 03 Jun 2003
Posts: 15079
Location: IRONMAN BABY!

PostPosted: Thu Jun 12, 2003 9:00 am    Post subject: Kevlar Tyre liners Reply with quote

Anyone use the below ( last item on page )

http://www.changing-gear.com/acatalog/CG_Catalog_Continetial_72.html
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Daz




Joined: 15 May 2003
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Location: Hampton, London

PostPosted: Thu Jun 12, 2003 9:40 am    Post subject: Reply with quote

Might be an idea if you have a separate bike you can use for training. But I wouldn't bother using this on your racing bike. I may be wrong, but I'm pretty sure the rolling resistance will increase as the tyre becomes slightly softer, despite the same psi being pumped into the tube.
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Robert




Joined: 15 May 2003
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PostPosted: Wed Jun 18, 2003 11:24 am    Post subject: Reply with quote

Sorry, Daz - it doesn't affect the rolling resistance as it doesn't affect the tyre, only the inner tube. You may find a difference if you put it o a scientific test but I defy anyone to notice more than 1sec per 100Km. Also, the weight is as negligible as wearing a heavy pair of sunglasses.

Given the risk to your race should you get a flat (especially in sprint tri), I think it's a worthwhile investment. You can also get tyres that have similar protection built into the tyre wall. Vredestein used to do one - not sure if they still exist.
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Daz




Joined: 15 May 2003
Posts: 11694
Location: Hampton, London

PostPosted: Wed Jun 18, 2003 11:51 am    Post subject: Reply with quote

Think you are refering to the kevlar beaded and not kevlar tape rob...

There was a section in 220 last year about tyres and various innovations, additions that could be made. Unfort the kevlar tape, although great for reducing the chances of punctures, DO add to weight in the wheel which affects rolling resistance. Also the extra addition of material between tyre and tube increases rolling resistance.

Did a quick search just now and found a few little notes

http://www.blayleys.com/articles/tyres/index.htm
http://www.bicyclecommuter.com/obstacles.htm

In training it might be a good investment if you do plenty of mileage, but I havn't met a triathlete yet that uses them (anyone else?), so there could be other reasons....

Tyres are getting stronger and lighter these days. Bought some Corsa CX the other day at 30 (think they are featured in the recent Cycling Plus mag). Told they are almost impenetrable, light as a feather and they go up to 160psi! Can't argue with that!
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ed_m




Joined: 15 May 2003
Posts: 8077
Location: coventry

PostPosted: Wed Jun 18, 2003 12:46 pm    Post subject: ... Reply with quote

hmmm.. as an engineer i'm not very happy with this definition of rolling resistance!

added weight (especially at the rim) will increase the wheel's inertia & hance make accel/deccel harder.

the weight itself won't however (i don't think) effect drag (aero or road!) from the wheel.... tho i agree the addition of an extra layer it's 'give' and movement withon the tyre/tube/liner combo could increase the amount of energy lost.

anyone ?
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Daz




Joined: 15 May 2003
Posts: 11694
Location: Hampton, London

PostPosted: Wed Jun 18, 2003 1:23 pm    Post subject: Reply with quote

I'll try and find the 220 mag that covered it....got the stack at home Smile
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andy collier




Joined: 06 Jun 2003
Posts: 178
Location: london, usually

PostPosted: Wed Jun 18, 2003 1:32 pm    Post subject: Reply with quote

Daz is there a test?

Theoretical arguments are fine and dandy, but I think the only answer is to time trial it - eg if it adds 1 minute over 50km but reduces the chances of a puncture by 90%, its worth it in my book

if it adds 15 minutes, it isn't
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Daz




Joined: 15 May 2003
Posts: 11694
Location: Hampton, London

PostPosted: Wed Jun 18, 2003 1:40 pm    Post subject: Reply with quote

Andy,

I think it was theory. But must be somethign somewhere on the WWW. Razz

I was thinking about this and personally I'd prefer to risk getting puncture on decent pair of strong racing wheels than kevlar insert (or beaded) even if it would just save me 10secs!!!!!

I've got to the stage now where I'm fine tuning everything to take off valuable seconds. I've done around 14 tri's in my three seasons without getting a puncture. In my last one I came 16th - but would have dropped outside the top20 (21st) if I'd lost just 10secs, it was that close.

Does anyone else take this approach? How much time would you be willing to drop just because you were worried your tyres might get punctured in a sprint?
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Robert




Joined: 15 May 2003
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Location: Back from outer space

PostPosted: Wed Jun 18, 2003 1:54 pm    Post subject: Reply with quote

Yeah but you got a double puncture on our ride down to the coast - if you did that in HIMUK, it'd lose you 15-20 mins.

As Andy says, worth getting if only lose secs over 50K but not if mins
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Daz




Joined: 15 May 2003
Posts: 11694
Location: Hampton, London

PostPosted: Wed Jun 18, 2003 2:07 pm    Post subject: Reply with quote

Yeh but that was my training bike with cheap tires Wink
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andy collier




Joined: 06 Jun 2003
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Location: london, usually

PostPosted: Wed Jun 18, 2003 2:29 pm    Post subject: Reply with quote

depends if its sprint or distance
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Kestrel13




Joined: 17 May 2003
Posts: 12
Location: Bournemouth

PostPosted: Sat Jun 21, 2003 9:10 pm    Post subject: Tyre liners Reply with quote

I've used this very product on my training bikes for the last two seasons and have covered over 5000 miles without a puncture! Very Happy Given that last season I had a Continental 4 seasons cut across the tread to the bead and its still running at 120 psi I call this a good investment. Cool Strange though it might seem I don't enjoy changing an iner tubes during a ride even if it's not chucking it down Shocked
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G




Joined: 15 May 2003
Posts: 45

PostPosted: Mon Jun 23, 2003 10:14 am    Post subject: Reply with quote

Can't believe I missed this thread for so long. These seem the answer to my prayers Very Happy

On a flat course then the additional few grams isn't going to make a jot of difference, and I can't honestly believe anyone would notice the difference on any other course for that matter.

Punctures used to be the bain of my life and even now with 'better' tyres I get them only infrequently the thought of never getting another puncture is a dream come true.

Anyone know if it is possible to get a puncture with this rim tape on? Obviously I mean through normal road use and not trying to stick a knife through it etc...

If so the additional weight could be offset against not carrying the spare kit.

Cheers

G
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Cougie




Joined: 21 Jun 2003
Posts: 1900
Location: NW

PostPosted: Thu Jul 03, 2003 4:49 pm    Post subject: Reply with quote

Really can't see why anyone should get so many punctures in a race that they need an extra kebvlar belty thing. I'd check my tyres. Punctuires should be pretty rare these days if your tyres are fine, at the right PSI, and you don't ride through potholes.

(As I did once - on my Tribars, rushing to meet my mates for the Club Run - hit pothole - flatted front tyre. Fixed that. Set off, and realised I'd blown both tyres on the pothole - doh ! )
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thinman220
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PostPosted: Fri Jul 04, 2003 10:20 am    Post subject: Reply with quote

If you are really worried about flats Kairfree do a foam liner. Some people recon they are heavy but I have heard many a story about people using them and winning races and getting large nails etc inserted without puncture. I punctured on a sprint a couple of years back and had to walk the bike back to the start some 2 km. Moral, I now run expensive but bullet proof contis and hope to hell they do their job!
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