Mtn bike puntures

[paulvs]

 

I think 2 bar is too little unless you weigh the same weight as your bike. Been riding with slime and tyre liners for about 2 years now and have yet to lose any time with a puncture. As far as affecting my perfomance in a race the top dogs have no fear of me.

 

I ride with 2bar and I definately do not weigh 13.5kg....

 

Do you weigh 63.5kg's

 

[shifter]

Thanks everybody, I now have choices,  you've all been great. Sorry about offending some!!! with my Scott. Who knows maybe one of these days I will get good enough to upgrade.

[bored girl]

I think 2 bar is too little unless you weigh the same weight as your bike. Been riding with slime and tyre liners for about 2 years now and have yet to lose any time with a puncture. As far as affecting my perfomance in a race the top dogs have no fear of me.

 

I ride with 2bar and I definately do not weigh 13.5kg....

Do you weigh 63.5kg's

 

what formula is this? bike weight + 50kg? cos it seems no one proved it works  def do not weigh that.....came close like 6yrs back but got a bit of a scare....

[bored girl]

Thanks everybody' date=' I now have choices,  you've all been great. Sorry about offending some!!! with my Scott. Who knows maybe one of these days I will get good enough to upgrade.[/quote']

 

Ag we just taking the piss out of the topic nothing wrong with Scotts

[paulvs]

 

HEY! I ride a Scott.... yep it's all about progression shifter!!! 

paulvs2007-11-27 04:15:00

[scotty]

I think 2 bar is too little unless you weigh the same weight as your bike. Been riding with slime and tyre liners for about 2 years now and have yet to lose any time with a puncture. As far as affecting my perfomance in a race the top dogs have no fear of me.

 

I ride with 2bar and I definately do not weigh 13.5kg....

 

Ah... but then you're a girl.

 

Ooops running to hide away quickly.  

 

 

[bored girl]

I think 2 bar is too little unless you weigh the same weight as your bike. Been riding with slime and tyre liners for about 2 years now and have yet to lose any time with a puncture. As far as affecting my perfomance in a race the top dogs have no fear of me.

 

I ride with 2bar and I definately do not weigh 13.5kg....

 

Ah... but then you're a girl.

 

Ooops running to hide away quickly.  

 

 

 

so what you saying is even if I put on 20kg I can still ride at 2 bar cos I am a girl?

[Johan Bornman]

The lower the pressure the lower the rolling resistance

 

Nonsense.

[Red Zone]

the best way to avoid punctures is, Dont ride over sharp objects!

[Ox_Wagon]

No, it even simpler. DO NOT RIDE Ox_Wagon2007-11-27 23:21:47

[Red Zone]

how can you not ride! just take the tyres off

[_Daemon_]

perma tubes!

[Thug]

 

The lower the pressure the lower the rolling resistance

 

Nonsense.

 

Why is that Johan ?

 

According to a graduate dissertion on rolling resistance utilising Schwalbe tyres, tyres at a lower pressure reduces rolling resistance.

 

http://www.bicicletta.co.za/Downloadable%20docs/Rolling%20Resistance%20Eng%20illustrated.pdf

 

 

 

 

 

[Ox_Wagon]

When I studied I commuted on what my dad called a Plumbers job (Tubes made of lead pipe).  I ended up install purma tubes.  It was amazing the amount of part that simply died from fatigue, including two forks. I have nice scars to show after a catastrophic fork failure.    <?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

[paulvs]

 

The lower the pressure the lower the rolling resistance

 

Nonsense.

 

Why is that Johan ?

 

According to a graduate dissertion on rolling resistance utilising Schwalbe tyres' date=' tyres at a lower pressure reduces rolling resistance.

 

http://www.bicicletta.co.za/Downloadable%20docs/Rolling%20Resistance%20Eng%20illustrated.pdf

 

 

I O think JOhan should stick to building road wheels and drinking beer

 

[/quote']

[Johan Bornman]

Why is that Johan ?

According to a graduate dissertion on rolling resistance utilising Schwalbe tyres' date=' tyres at a lower pressure reduces rolling resistance.

http://www.bicicletta.co.za/Downloadable%20docs/Rolling%20Resistance%20Eng%20illustrated.pdf


[/quote']

 

That study wasn't controlled well enough to tell us anything meaningful. To say that he rode over the same grass or gravel patch in each leg of the test is wishful thinking. Futher, how do you maintain a constant speed on a bike? You cannot.

 

The only way to create a perfectly controlled study is on a drum in a lab. That way you can control the surface, speed, input power and of course, measure the resistance. If you look at the figures in the study, they're so close together that the slightest bit of noise skews the data. For instance, the tested said he maintained a constant speed to eliminate wind resistance. Well, what about wind. How did he control the elements? How did he control the deformation of the grassy strip after ten passes?

 

It's a nice attempt, but like with so many of these things, the most obvious variables were not controlled.

 

As to your question why a lower pressure produces a lower RR? When a tyre is deformed, energy is lost in reforming it at the exit end of the cycle. The more rubber in there, the more energy lost. Air also loses energy, but very, very little inthe case of pneumatic tyre.