BergForce Posted May 9, 2012 Share Under stress you will have flex in the tire, rim, spokes, and fork, all adding up to the total amount of flex. The thru-axle will reduce the total amount of front end flex. Link to comment Share on other sites More sharing options...
sometime Posted May 9, 2012 Share The answer to your question is yes, since it will have the same sidewall consturction, with the same amount of PSI to leverage the weight there will be no difference whatsover, there will be a difference on the amount of rubber contact on the ground though. So if I follow your reasoning you can also run your road bike tyre (assuming the same sidewall construction) at 2 bar for a 100kg rider? Link to comment Share on other sites More sharing options...
covie Posted May 9, 2012 Share So if I follow your reasoning you can also run your road bike tyre (assuming the same sidewall construction) at 2 bar for a 100kg rider? If the tyre is the same width and height with the same sidwall construction yes it will work, The total diameter is irrelevant in this equation as it will take more air to get a 29'er tyre to 2.0 bar, but the resistance of 2 bar is guess what 2 bar. So yes its still irrelevant. Link to comment Share on other sites More sharing options...
sometime Posted May 9, 2012 Share If the tyre is the same width and height with the same sidwall construction yes it will work, The total diameter is irrelevant in this equation as it will take more air to get a 29'er tyre to 2.0 bar, but the resistance of 2 bar is guess what 2 bar. So yes its still irrelevant. Agreed - now we're getting somewhere. So on the assumption that the surface area is the same for all tyre sizes then 2 bar for any tyre diameter is 2 bar. But the surface area of a 9" tyre is quite different as is that of a road bike tyre hence the very different pressures required on each to support the same weight. Question is is the surface area of a 29" tyre the same as a 26" tyre? Link to comment Share on other sites More sharing options...
covie Posted May 9, 2012 Share Agreed - now we're getting somewhere. So on the assumption that the surface area is the same for all tyre sizes then 2 bar for any tyre diameter is 2 bar. But the surface area of a 9" tyre is quite different as is that of a road bike tyre hence the very different pressures required on each to support the same weight. Question is is the surface area of a 29" tyre the same as a 26" tyre? No you still lost the plot here, If yo u have a 9" tyre with a 5cm high sidewall, and 2.2 inches widthand a 26" tyre with a 5cm sidewall and 2.2. inches widthand a 29" tyre with a 5cm sidwewall and 2.2 inches widht all running at 2 bar they will all do exactly the same thing. The surface diameter you describe will assist in grip acceleration and breaking and thats it mate. Link to comment Share on other sites More sharing options...
Dicky DQ Posted May 9, 2012 Share Agreed - now we're getting somewhere. So on the assumption that the surface area is the same for all tyre sizes then 2 bar for any tyre diameter is 2 bar. But the surface area of a 9" tyre is quite different as is that of a road bike tyre hence the very different pressures required on each to support the same weight. Question is is the surface area of a 29" tyre the same as a 26" tyre?No it is not. This is also why when motor vehicle manufacturers try to get better performance out of their cars they opt for lower tire profiles. So again it (for Covie, does make a difference what happens away from the tire) the final amount of flex what what depends more on the tire than anything else. Link to comment Share on other sites More sharing options...
covie Posted May 9, 2012 Share No it is not. This is also why when motor vehicle manufacturers try to get better performance out of their cars they opt for lower tire profiles. So again it (for Covie, does make a difference what happens away from the tire) the final amount of flex what what depends more on the tire than anything else. jeeez ok i give up what does a low profile tyre do increase or decrease the sidewall height?.... FFS dude seriously enough is enough you dont have a bloody clue. Edited May 9, 2012 by covie Link to comment Share on other sites More sharing options...
Dicky DQ Posted May 9, 2012 Share Anyway I am over and out...... I know what is and what is not, one day you peeps can show me the difference in a lab.. Link to comment Share on other sites More sharing options...
Dicky DQ Posted May 9, 2012 Share jeeez ok i give up what does a low profile tyre do increase or decrease the sidwall height?.... FFS dude seriously enough is enough you dont have a bloody clue.?? http://en.wikipedia.org/wiki/Tire?? Link to comment Share on other sites More sharing options...
covie Posted May 9, 2012 Share ?? http://en.wikipedia.org/wiki/Tire?? you found wikipedia.. I am truely amazed now. Link to comment Share on other sites More sharing options...
Dicky DQ Posted May 9, 2012 Share Profile is the ratio of the sidewall vs the width of the tire. Link to comment Share on other sites More sharing options...
covie Posted May 9, 2012 Share Profile is the ratio of the sidewall vs the width of the tire. Exactly dude, i.e having a 5cm sidwall vs a 2.2 inch width as stated in my post above. Got buggerall to do with the DIAMETER damn. Link to comment Share on other sites More sharing options...
sometime Posted May 9, 2012 Share No you still lost the plot here, If yo u have a 9" tyre with a 5cm high sidewall, and 2.2 inches widthand a 26" tyre with a 5cm sidewall and 2.2. inches widthand a 29" tyre with a 5cm sidwewall and 2.2 inches widht all running at 2 bar they will all do exactly the same thing. The surface diameter you describe will assist in grip acceleration and breaking and thats it mate. Thanks Mate! Physics tells us that in order to support a given weight, with a given pressure, the surface area must be the same. (all other things being the same) So back to my original question which you dismissed as me "missing the plot". Does a 26" MTB tyre have the same surface area as a similarly constructed and dimensioned 29" tyre? Link to comment Share on other sites More sharing options...
Dicky DQ Posted May 9, 2012 Share Have a beer on me Covie...I got to go get one myself and work out all this stuff, but hopefully other peeps will get insight........... or not. Link to comment Share on other sites More sharing options...
covie Posted May 9, 2012 Share Have a beer on me Covie...I got to go get one myself and work out all this stuff, but hopefully other peeps will get insight........... or not. Im drinking wine like mad to try and get drunk enough to continue this conversation, you have demostrated you have no idea how tyres work, you dont have a clue how the forces are applied to your bike rims, spokes, and hubs. And yet you argue. I dare you to mail all the bike manufacturers and let them know your gem of knowledge so they can convert all DH bikes to QR as it will same them some weight. Please post the replies here. Link to comment Share on other sites More sharing options...
RockCoach Posted May 9, 2012 Share Thanks Mate! Physics tells us that in order to support a given weight, with a given pressure, the surface area must be the same. (all other things being the same) So back to my original question which you dismissed as me "missing the plot". Does a 26" MTB tyre have the same surface area as a similarly constructed and dimensioned 29" tyre? In your physics calculations... Which surface area are you going to put into your formulae? The circumferential surface area (around the outside perimeter) or the cross sectional area (if you cut through across the tyre)? Link to comment Share on other sites More sharing options...
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