inflation guidance

[mikebaileyvienna]

Reading the manual, it says if you are heavier than 198lb to increase the tire pressure, but goes back to the lower pressure if you plan "high speed riding." Questions:
**Do you increase the pressure in some sort of continuum as you increase weight? With my daily gear, I'm at about 195lb. My pressures right now are 34/38, kind of in the middle. Thoughts?
**My spring is currently set at 5. Thoughts?
**Why do they recommend reducing pressure for high speeds, and by "high" do they mean track speeds, or highway speeds?


Thanks

 

[Michael Wilson]

1psi of air pressure in your tire is equal to 10 pounds of spring rate from the suspension. Don't ask why I know this or how I know this I just do lol. I'm assuming they say lower the pressure for high speeds so you have a wider contact patch on the ground. I've always ran 35 in both and been just fine.

 

[Detrich]

Stock suspension setting (3) is for a rider weighing about 150 lbs. My Yamaha dealer sets up the tires at 36 front 40 rear for street, and for me, it works well for street & canyons. It really depends your weight, how hard you ride, and how hard you work your tires.

 

[Fizzer6R]

mikebailey, i wouldn't concentrate on a specific number, see what feels best for you as it may not for another rider. my numbers are usually closer to yours, instead of higher like Detrichs

 

[buzzbomb]

All I can add is that I made the mistake of running my tires at the pressure stated on the side, rather than in the factory recommended. It very quickly resulted in a flat stripe, down the center of my rear tire.

I've always done my tires that way. I just thought they wore that way because that's how tires wear. I now ride with the pressure according to my weight, and what the manual says. It'll take a new set of tires to gauge the impact of that, for me, and that hasn't happened, yet.

As for increasing tire pressure in a curve with load-weight? Once again I'd try to match it to the manual, or the sticker on the swing-arm.

Your spring setting seems a bit high, but without some pretty complicated setup that involves multiple people loading for you (as taught in "Twist of the Wrist II) I just go by what I like. The end result probably isn't perfect, but to get it perfect takes a lot.

Your last question is something of a conundrum, as I also don't know what they mean by "high speeds." My assumption is that it's related to track riding, and not highway. Or a person who rides the street like they think it was a track.

It's still iffy, though. Higher pressure increases the roundness of the tire, while decreasing deflection. There's a lot to be said for that. Lower pressure increases the contact patch and allows the tire to deform more in a turn. Also a good argument.

I don't ride track. I truly have not clue how to properly set up a bike for a race. I'd say that for most of us, just sticking to what the manual or the sticker says is a pretty good bet.

 

[Detrich]

From what I understand, tire psi expansion at the track is very high- due to the high heat and hard riding. On a hot day riding hard you can prolly observe psi's go up 5 or 7+... That's why track riders always under-inflate. Normal riding prolly only raises psi's by 2 or 3+ max. Canyons maybe 3 or 4 psi max.

Again, it all depends how hard you work your tires. As long as you inflate them within a safe range that matches how you ride, you should be ok.

Obviously, using street psi settings for track may not work well, because your tires will expand too much and might be overinflated- sacrificing much needed traction. Under inflating will make your bike handle like crap and more sluggish. You'll have more difficulty cornering and also wear out the tread prematurely.

There are no exact perfect settings. That's why finding the right range is the safest way to go. Unless you measure your tire pressure religiously and monitor that is. But it's often impractical or inconvenient.

 

[FastFreddy]

Thoughts :

- My pressures right now are 34/38, kind of in the middle.
Personally I find 34 too squishy at the front, I like 35 or 36 PSI, so its 1 or 2 PSI above that too squishy feeling for me.


- **My spring is currently set at 5. Thoughts?
That's too hard at the back for me. I weigh about 210-220 lb and find 4 perfect for me. 5 was restricting the rear travel (in droop) for me, that's bad, it means the tyre is losing contact with the tarmac. 5 does feel good when its not topping out or hitting a bump, but I prefer softer and slightly slower steering for me. (in the middle of flighty quick steering or too slow steering, just right is what you want)

One thing to understand is that with the combination of spring preload and tyre pressure (and shocks if you have adjustable clickers), you are establishing a front to rear stiffness balance. The stiffer you go in the rear, the quicker the bike should turn, there should be a ratio of rear to front stiffness that suits you. If you go too hard up front, the bike will be harder to steer but have more stability. I've found with car suspension tuning which I have more experience in, its the overall stiffness of all the components, you have to keep the balance and ratio's similar. What this means if you change one setting, you should be compensating front to rear with the other components to keep a similar desirable balance.

 

[FastFreddy]

I'm talking about general riding settings, if you are on track you'd drop it more as Detrich explains.

 

[FastFreddy]

I had a dodgy puncture self-repair the other week on the rear and its was down to 25 PSI. It hooked up good in a straight line like that, I suspect 25 PSI would be good for drag strip work.

(I put a new rear tyre on the next day)

 

[FastFreddy]

If the rear gets too hard, it'll spin up easier (more slip) and also give less feel at the rear. 38 PSI is a good start, try 37 and 39 and see what you prefer.

I'm 36/38 at the moment and sometimes go 35/37.

With the new rear tyre which has more tread flex, I'm on 42 PSI (Road 2) rear and it feels the same as the old tyre on 38 PSI (Q2)