Numpty IM Bike Thread

Bike ponces only welcome if they don't speak in tongues

11,481 to 11,500 of 12,108 messages
Golden Boots    pirate
24/04/2012 at 17:43

Thanks Pebble, may look to purchase in the forthcoming weeks then

Iron Muffin    pirate
30/04/2012 at 10:33

Morning bike brains.

Please can someone help with my numpty question of the day.

Do inner tubes have a max pressure and if so how do I check?

I inflated my new tyres to 120 (it said upto 140 was okay) and then a tube blew up. It may have been 'pinched' as I had just changed the tube and was wondering if it would have been the extra pressure or my tube chagning numptiness.

30/04/2012 at 10:59
sounds like tube changing numptiness

it's almost impossible to overinflate a tube as it's contained in the tyre - it's the tyre that dictates the max pressure. unless of course there was a fault in the tube, which is not unheard off - I've had a few new tubes refuse to inflate and the problem's usually around the valve, often with a split.

pinch punctures will go at higher pressures so always be careful when putting them in as it's easy to trap the tube between the rim and tyre

one other question - why 120psi?? I'm pretty heavy and rarely go beyond 110psi on my racing wheels - for my training tyres I stick at around 100psi

Iron Muffin    pirate
30/04/2012 at 11:14

Thanks FB.

Why 120 psi? The misguided belief that I may go fatser and get less punctures.

How do I work out the best psi?

30/04/2012 at 11:56
I stick 115 in the dry - a bit less in the wet - although the Vittorias on my race wheels actually say minimum 120psi !

I wouldn't worry too much - look at the side walls of the tyres and keep them within that range. Heavier riders generally stick more towards the top end of the range in, wet weather or rough roads stick a bit less in.

FB is certainly right that you don't need high pressure - the science suggests closer to 100 you get lower rolling resistance I just prefer the feel of a having them a bit harder(!)
30/04/2012 at 12:02
"How do I work out the best psi?"

based on what others do.... it's somewhat a case of trial and error and experience and you can work within quite a large range but not see that much difference

it's marginal how much quicker you'll go at higher pressures - certainly when you get past 100psi or so. high pressures should mean less tyre contact with the road so more speed, but as pops says, the science here is a bit sketchy. you're also at a greater risk of a pinch puncture should you hit a pothole with high psi (assuming you're not on tubs)).

the other issue with puncture frequency is type of tyre (kevlar reinforced ones tend to be more puncture proof), age of tyre (old ones become thinner so more prone to punctures), tube quality, and of course road surface/debris etc.
Edited: 30/04/2012 at 12:06
Iron Muffin    pirate
30/04/2012 at 13:17

The tyres in question are clinchers, Schwlebe Ultras (?!?) apologies bike aficionados.

Girlie purchase I am afraid.... the matching colour strip did it.

My first pucnture was bizarre and has marked the tyre. No raod debris, nothing in tyre, nothing to explain it.  The good thing was how easy the tyre was to change after my last ones that were full of metal strips.

I didnt even cry, swear or take 3 digits worth of minutes.

30/04/2012 at 14:50
probably Schwalbe Ultremo ZX as they come in different colours - some people have complained about them having soft sidewalls and puncturing easily - see here - maybe what you've seen MT??

my everyday training wheels are shod with Continental Gatorskins which are pretty bullet proof until they get well worn.
Iron Muffin    pirate
30/04/2012 at 20:55

That will learn me..........pick tyres with colour stripes to match and run the risk of more punctures.

Will probably take your advice on replacements in a few weeks.

Cortina5    pirate
30/04/2012 at 21:03

Next Numpty question - How can I get my bike to Marshman?

Normally I'd throw it in the car, but we're staying Hastings for the weekend so car space at a premium. We have an old battered rear mounted carrier I use for my MTB/road bike. Will this be OK for my carbon baby?

I also borrowed a Halfords roof mount rack but this has a clamping claw for the downtube that wasn't designed with aero frames in mind.

Final option is to by something like an Elite San Remo that clamps the rear wheel and the front fork.

Once we've got to the cottage I'll throw it in the car.

Doner Kebab    pirate
30/04/2012 at 22:41
Cat - i dont know how true this is but did see/read/told a while ago that you shouldnt put carbon bikes on roof racks at motorways speeds, it can twist them???? or something - like i said dont know if its true or not. I use pipe lagging round my frame when using a rear bike carrier to protect it from the straps and bungees and road vibrations.
ChallengeGoGoGas    pirate
30/04/2012 at 22:50
Good tips on pipe lagging there DK!
cougie    pirate
01/05/2012 at 00:27
My bike has done plenty of motorway miles. If it can cope with fast alpine descents with riders on it - a bumble down the M6 isn't a problem ?

No frame will twist at motorway speeds in a bike rack.

The only thing you need to watch fr is crushing the tubes when you clamp the bike in.

Best bike carrier is off a tow bar - but failing that boot racksbre fine. Pipe lagging is a good idea.
Cheerful Dave    pirate
01/05/2012 at 06:25
Another option: borrow a roof box for all the other stuff that you're taking and put your bike where it belongs: in the car.
Cortina5    pirate
01/05/2012 at 08:05

Cunning CD. We have a roof box......I had already thought of that for Outlaw. I suppose I could take the wheels off.

Now to see if the kids fit in the roof box!

Cheers All.

01/05/2012 at 09:01
you could always ride down C5......

01/05/2012 at 15:06


You know those 60mm clinchers I bought? Can't even get close to fitting a tyre onto them. Got everything else tickety-boo.... rim tape, new cassette, 80mm valve inners..... but I cannot for the life of me get a tyre on the bugger.

The tyre's a Conti GP Tri that I raced last summer before I put Hardshell's on for the winter, so it's a decent tyre, but it has been hanging up in the garage all winter. Do they shrink, or lose elasticity, by any chance?

I have some other tyres to choose from. Failing that, I buy plenty of kit from a couple of LBS so wouldn't feel too much of a charlatan popping down and asking them to have a look.

Any thoughts, chaps, please?

01/05/2012 at 15:21
I've had the same problem with Michelins on Campag rims.

Warm the tyre on a radiator or in the oven (be very careful if you use the oven!), use talc, or use vittorias or Schwalbes as they seem to be looser. People reckon thinner rim tape makes a surprising difference but I've always just persevered and eventually you get there - even if you have to scrap several inner tubes in the process !
01/05/2012 at 15:30
tyre can lose elasticity (rubber perishes) but not in that timescale and I've not heard of one shrinking. and some wheels can be a bugger to fit tyres on - my Campag Neutrons are always a battle with fresh tyres.

have you tried a tyre off another wheel that's you're using?? that should be "slack" enough to fit. that should tell you if the wheel is the correct diameter

alternatively, warm the Contis in very hot water or with a hair dryer (not too close!) as that should make the rubber more supple, and then try again.

and do all this without a tube in as you might need to lever the tyre on so no point damaging a tube. if you manage to get the tyre on, take it on and off another couple of times to stretch the beading a bit before sticking a tube in.

let us know how you get on

EDIT: x-post with pops
Edited: 01/05/2012 at 15:31
01/05/2012 at 20:13

I bought some new wheels last Friday, and the front one at least has arrived! (Shimano Dura Ace 7900 C24 CLs, since you ask)

Noob questions as its the first new wheels I have bought...

Do I need to DO anything to them to prep them for use? (oil / grease hubs / check spoke tension - how?!) etc?

Should I keep the plastic hub plugs that came with the wheel? They'll live in the wheel bag when not in use

Does the QR skewer need greasing at all?

Also, for when the back arrives, what tools do I need to get a new cassette on? (am thinking Shimano Ultegra 11-25 probably, have a 12-25 on current wheels)

All comments / suggestions gratefully received!

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