higher tyre pressure = tougher ride?
 

hello,
i am 6ft 10ins,47 year old and about 330lbs..i cycle with several fit riders over very hilly terrain and we are too competitive at times..anyhows i have my specialised armadillos at 85 psi and have struggled and been lagging behind..feels like riding with the brakes on!..now 6 weeks after last pump tyres seem a littlr deflated and riding is easier...logic suggests higher psi = less tyre on the deck=less friction etc etc but, i am finding it easier ridng lower psi ...any thoughts?
BTW which part of your foot do you taller fellas use to pedal?..i have tried the ball,arch and now finding the heel gives me a little more drive..the ball stretches my leg muscles a lot at times..
cheers
mark
plymouth
uk

I the lower tire pressure may make for a smoother ride so you may feel more comfortable, but I can't believe it is easier. On my road bike I check my tire pressure regularly. I find the pressure goes down after a day or two. On my MTB the pressure doesn't decrease as fast, so maybe at 85 psi you aren't loosing much pressure. It seems odd that you feel like you are riding with the brakes on, I would say that is the low pressure, but then you say it is easier at even lower pressure humm. Maybe it is easier six week later, because you are in better shape.

I use the ball of my foot over the center of the pedal. I would suggest you check your fit. For starters with your riding shoes on put your heel on pedal and extend your leg. Then when you move to the ball of your foot you should have a slight bend. You should feel more power using the ball of your foot...maybe win a few of those sprints to the speed limit signs.

Hi,
I run 90 psi and need to top them up once every two - three days. If I am reading your post correctly, you need to check the air before you go out again. I think that if you run your tires at max psi for the tire, you tend to get less flats - could be an urban myth. I think it is correct to say that most folks use the ball of the foot. BTW - what bike do you have and the size?

The manufacturers started testing rolling resistance on steel drums a few decades ago. This may have been a big step backwards, as those tests showed that rolling resistance decreases with increased air pressure -- no exceptions. The problem is that the real world is not a smooth steel drum. It turns out that over real-world roads -- ie. ones with bumps -- narrow high pressure tires aren't always as fast as wider lower pressure tires, and that increasing pressure in those narrow tires can make them even slower. Essentially, it takes energy to bounce you and your bike around, and the more you and your bike are bouncing the more energy it takes. The bouncing you and your bike will do when riding, for instance, cobblestones on 19 mm clinchers at 180 PSI sucks up a surprising amount of energy, and if you've tried it, you'll know how much it slows you down. Try a pair of 28 mm tubulars with 90 PSI and you'll actually go faster -- and without nearly so much bouncing. Hmm...

I have no experience with Specialized Armadillos, and I have no idea what a bike feels like with 330 pounds aboard, but perhaps the above ideas may be useful for the OP.

The general rule is that rolling resistance is reduced with higher pressure, the cost of that is a harsher ride. With an AL frame that harshness can be very tiring.

If you need to ride with the heel of your foot, either your saddle is not positioned correctly or the frame is the wrong size. A lot of riders with platform pedals do ride more on the arch then the by the proper position by the front of the foot (behind the toes), which is where clips or clipless pedals position your foot. This can also making riding more difficult. If you could post a picture of you riding, from the side, it would be easier to tell what the issue is.

I pump up to 110 psi.

FWIW I'm 220 and ride 700x23 on my roadbike. For me the perfect setup is 120 on back and 110 on front. Bouncing around with 120psi may be an issue for a little guy but reality check, I ain't doing much bouncing at 220lbs. If your bike fits right you should have ball of foot on pedal or better yet try clipless.

+1 almost exactly the same but 5 lbs heavier. Not too harsh and no pinch flats (which I used to get, but it depends on the road conditions you ride)

yup. 25 wide and at least 120psi. conti ultra gatorskins w/kevlar. durable, reasonable ride and grips well enough. theyre like fat black donuts around my rim.

i would run a 28 if i could, but the frame will only handle a 25.

im as gentle on wheels as a 100lb 14year old female junior, but id never, ever, ride under 100psi. i dont understand how some of you, us, clydes are running 85psi, or what i would consider a partial vacuum, without pinchflating getting on, your bike.

enjoy, spin classes are almost done for the year :) the women are pretty hot, though :(

u also have to consider tire size, with the 23x700c's i have on my road bike, i run 125 psi... but on the hybrid i had a while back, i had 37x700c's at ~100psi, and sometimes i'd over inflate them to ~110psi...

also, most tires have a minimum pressure, run to close to that minimum pressure and add the weight of a clyde, and u can run the risk of pinchflats... in fact i think Sheldon Brown suggests over inflating based on total weight (rider, bike, and gear), but following the guide he created i should inflate my 23's to over 200 psi :twitchy:

Selected tire pressure should be a result of the load put upon a tire.

Maximum tire pressures, suggested by manufactures indirectly represent a "load maximum" as well.

If a tire deforms "excessively" during use while inflated to it maximum pressure, then the tire is being used beyond its suggested load capability.

However, most tires can be used beyond their "suggested" pressure/load capability. It is up to each cyclist to study the tire deformation, at both pressures, and determine if excessive pressure will lessen tire/wall deformation and thereby increase performance.

In many cases, over inflating a tire will not improve performance. For at least some tires it will.

Here in S E Michigan the roads are so bad I can't imagine trying to ride skinny rode bike tires !! I started out at 371 # on a cruiser 7 speed . Not to bad a ride considering the roads I have to deal with . Switched to a comfort bike with a front shock and 700x35 tires and its much better ! But ive lost a ton a weight . I run my tires at max + 5 pounds nary a problem . I am even running cheap tires price wise Kenda kouriers seem like awful good tires for the $$ but only a couple hundread miles on them so far . Max on my tires is 85 and I run them at 90 psi .

I am of the mindset that higher/lower pressure has no material effect on speed/resistance. There may be roll resistance factors at work, but not enough to feel on the average rider. It may provide a smoother/rougher feel for some rides. Lower pressure certainly does provide a tad more stability on wet roads however due to a slightly larger tire footprint. That said, I usually maintain between 100 - 110 psi. My tires are rated to 140psi, but I see no reason to go that high. I am 6'4" 237lbs. At my weight, I would however caution against having not enough tirep pressure, leaving me prone to punch flats, AKA snake bites. I would never ride below, say 90psi for that reason.

As for foot position on the pedals. Ball of the foot brings the more of the action of your entire leg into your pedal stroke. The more muscles you have "on deck", the less work load each has to bear-to draw an overly simple model. Imagine the the advantage in leg power a person swimming in flippers as opposed to a person swimming without them. The same is true with pedaling. With heels on the pedals, you use the upper leg, and eliminate the boot/ankle action.

After getting the balls of the feet on the pedals, I would focus on makinng perfectly round pedal strokes. I think of "unweighing" the foot at the top of the pedal and scraping the foot back on the bottom of the pedal stroke. Toe clips may help, and cleats are even better for efficiency. Efficiency means you can go faster and longer at the same energy level.

its funny you mention that. i have such a one track mind, that it didnt occur to me that people ride anything but a pure road bike, with 25-28 max tire width. guess i forgot about my xbike and mnt bike. duh

i treat the minimum pressure guidelines like i do the minimum speed limit on the highway, as do, im sure, the rest of you...a theoretical number, never to be seen in actual life. yeah, i think i once saw a chart that suggested i just ride on my rims, to avoid pinch flats, based on rider weight.

i didnt know there was an accepted position, other than having the ball of the foot, directly over the spindle.

OP: take off your shoes stand and walk on the balls of your feet. Then try this with your heels. You will notice a considerable difference in dexterity. The solution should be obvious.

More likely you got fitter. Harder tires are faster/easier. If you prefer riding with your heel on the pedal, your seat height may be a tad low.

Depends on riding conditions. On rough chip and seal pavement or sectioned concrete, lower pressure will ride easier and faster. On smooth, new asphalt, or a velodrome (not likely for many of us), pump it to the max.

That makes a lot of sense. Do you know of any research on the issue?

I feel sluggish pedaling anything other than rock hard tubes. Big dudes can make squishy tires.

When analyzing the system, you really need to consider energy. When you hit a bump you translate horizontal momentum into vertical momentum. In most cases, this does not get translated back into the horizontal momentum (a pump track is a noticeable exception). It gets bled from the tire bouncing. That flexes the tire wall which translates kinetic energy into heat energy. The heat energy then just drifts away.

In general the bumpier a surface gets, the more prudent it is to lower tire pressure. To a degree ... you don't want pinch flats. XC racers run tubeless and put as little pressure in their tires as is possible.

It's reasonable that road racers inflate their tire to a maximum. A well paved road does not require a highly compliant tire. At some point though, you wont gain any roll resistance from more psi. Your psi will require experimentation.

If you're on a bike with thin tires and you're actually bouncing up and down, you're doing something wrong. 19mm @ 180 psi on cobblestones? It wouldn't be bouncing that slows you, it would be just trying to stay in control. Most people riding on the road are not on cobblestones - or 180psi razor blades for that matter.

Rolling resistance as a function of road roughness
 

Maybe you can give some lessons to these guys, then. :rolleyes:

To the best of my knowledge, the work reported in Bicycle Quarterly is the most definitive to date. They have repeatably demonstrated that under real world conditions, wider tires (at least up to 27 mm or so) have lower rolling resistance than narrower (19-20 mm) ones of otherwise identical construction.