[dhkid]

http://www.ridemonkey.com/forums/showthread.php?t=190856&highlight=barracuda



i did it because barracuda's are very underrated. other tires i use are really main stream so no point.

 

[Rick205]

I dont want to add to the pot of worms but...

I was under the assumption more weight over a tire = More grip.

Is this not the reason were all lowering our front ends like sam hill?

 

[Banshee Rider]

I could have swore I typed in ridemonkey into my browser, not MTBR...

 

[Cant Climb]

i did it because barracuda's are very underrated. other tires i use are really main stream so no point.

What is your feeling on the proper PSI to run in all these different tires........have you experimented....?.....what are your findings.....?....

 

[dhkid]

cant climb - i run lower pressures then most people because i am very light, 130lbs. so take it with a large pinch of salt.

in maxxis 2.5s, i run around 21- 23 psi. the 2.5 barracuda's lower, in michelin comp 16 2.2, slightly higher.

i can only state the pressure i run on the maxxis because thats the only time i had a accurate pressure gauge.

the standard way of checking pressure for me is by cornering hard, sometimes on tarmac, to see if the tire folds over at all. i generally run a few psi higher so that i cant feel it fold over at all.

except for one track where i flatted on all my tires, i dont generally have problems with flats.

back home i was running high 30s in my michelin 24's 2.2 tho. i had those tires on so it would roll fast, might as well make it roll even faster, i wouldn't do that in a race, but it was just for fun, drift everywhere. makes riding a bit more fun. kinda like putting a HR semi slick on the back to keep things fresh.

 

[ChrisKring]

I dont want to add to the pot of worms but...

I was under the assumption more weight over a tire = More grip.

Is this not the reason were all lowering our front ends like sam hill?

It's more complicated than that. As the COG moves, the dynamics are affected.

 

[Steve M]

I dont want to add to the pot of worms but...

I was under the assumption more weight over a tire = More grip.

Is this not the reason were all lowering our front ends like sam hill?

As ChrisKring said, you get more grip force at that particular tyre (non-linearly) but then that tyre has to deal with more of the lateral load because more of your mass is up that end of the bike. In a static/steady-state cornering situation, you will get more grip from whichever end has LESS of your mass over it because available grip doesn't increase proportionally to the force on the tyre (on dirt anyway, it's somewhat linear on asphalt, with cars, up to a point anyway haha). Slip angles (the difference between the way your tyre is pointing and the way it's actually traveling relative to the ground) and slip angle differences between front and rear tyres complicate things even more. However, the way your weight is shifting as you enter a corner, hit the apex, and exit the corner is what really determines the grip available, and the way your suspension compresses/rebounds (ignoring significant leaning effects) delays changes so that you can hold the tyre against the ground more or less hard than the amount of weight over it. It's all to do with transient dynamic effects, and simply looking at it as a static system WILL give you inaccurate, misleading, and/or flat out wrong results.

I don't know of anyone who has actually quantified much of this with regard to mountain bikes, maybe DW has, but right now it's a black art.

 

[Cant Climb]

cant climb - i run lower pressures then most people because i am very light, 130lbs. so take it with a large pinch of salt.

in maxxis 2.5s, i run around 21- 23 psi. the 2.5 barracuda's lower, in michelin comp 16 2.2, slightly higher.

i can only state the pressure i run on the maxxis because thats the only time i had a accurate pressure gauge.

the standard way of checking pressure for me is by cornering hard, sometimes on tarmac, to see if the tire folds over at all. i generally run a few psi higher so that i cant feel it fold over at all.

except for one track where i flatted on all my tires, i dont generally have problems with flats.

back home i was running high 30s in my michelin 24's 2.2 tho. i had those tires on so it would roll fast, might as well make it roll even faster, i wouldn't do that in a race, but it was just for fun, drift everywhere. makes riding a bit more fun. kinda like putting a HR semi slick on the back to keep things fresh.

I was just curious if you experiemented as much with psi as you have with didferent tires....to me that seems to make the most difference....but most tires have a limited range of psi options because that flat soo easily (not a tubeless guy)......

Stick with maxxis try a couple different psi......find a your favorite mud tire for thoose rare occasions when you need them....OR if you love giving tires so much thought then carry-on with that too...but seems to me you're over thinking it.....

 

[dhkid]

well, i hope i am not over thinking it. i just classify each tire in a condition that would be optimal for it.

again, tire pressures, i just run as low as i can, which is still quite reasonable. so that they dont fold over, and that seems to be the biggest limiting factor to tire pressure, and i wont have problems with flats.

i generally dont run really hard pressures on most tires, but i do with tires like comp 24's. but comp 24's are naturally very round anyways since its designed for groomed courses. so the high pressures dont help anything except help it be more solid and roll faster.




anyways, could you explain how different pressured might effect the tires, ie what you have felt personally. and what do you mean by trying different tire pressures? go higher or lower? i cant go lower coz the tires will start to fold over. higher is the only way i guess, but when i was running my comp 24's rock hard, i was getting problems with high speed vibrations, my hands were going numb.