Campag4life

Most drop bar road cyclists have at least 60% of their overall weight over the rear wheel. Some a bit more.

Kontact

Until they hit a bump with the front wheel and the weight shifts. But you are correct that the split might be higher than what I used as an example - it depends both on rider position and frame geometry, as longer chainstays shift weight to the front wheel.

CliffordK

It also varies with ride conditions. So, if I'm climbing seated, I can hit closer to 90%, I think. It is a bit disturbing when I hit 100% on the rear.

Standing, it puts at least some of the weight forward.

I would assume a steep descent in the drops would do the opposite, with at least 60%, or more of the weight forward (also a reason for a light touch on the front brake).

CliffordK

Oh... so another pissing contest about tires and wheels.

I've been riding my cross bike and drop converted hybrid all spring.

I just got my road bike back on the road... 23 or 25mm tires. Oh, it feels nice.

Not a lot of solid data, but I've been pushing my speed and hitting JRA PR's. Although, also feeling a bit of road buzz in the hands

Still, I suppose the question should be comparing apples to apples. For example, finding a bike that will fit multiple tire sizes, and sourcing a single brand like gatorskins in multiple sizes.

Campag4life

All true. I meant steady state on the flat. You are right of course.

f4rrest

Now I want some 21s for my commuter!

CliffordK

The 60/40 is probably a good rule of thumb, but riding is never really in a steady state. I like to stand from time to time even on the level which pushes the weight forward.

One's hands and one's rump are also very different contact points.

There are usually far more complaints of hand numbness than rump numbness (although numbness in the sitting area does occur and can be very serious).

I presume one's arms absorb shock a bit better too, while hitting a hard bump sitting hard on the seat can really pound the bike.

Lots of different theories... fatter tires up front, skinny on the rear. Fatter on the rear, skinny up front. Perhaps it doesn't really matter.

I have started setting the rear tire pressure slightly higher than the front, but even that doesn't seem to be a big deal.

Personally, I usually only pump with a gauge once every few weeks, then like the OP, the rest of the time, just use my thumb as a guide. And, of course, pumping after a flat is usually on the road with the hand pump and no gauge.

Cyclist0108

There are steep climbs in Wilmette?

CliffordK

My own driveway has a short section of > 15% climbing. And, I don't drive enough to keep the fir needles clear (they act like roller bearings), so when it is wet, there is a fine line between sitting and getting wheelies, and standing and spinning.

There are a few steep spots around here, but I don't hit them too frequently. I should try it a bit more. I did one ride towards Crater Lake that had a sustained 10% or so climb for several miles, put me over the top when I was riding a loaded touring bike.

Someone has developed 3 ABSOLUTELY INSANE half century rides up in Portland. I think the average climb is about 10%, with some hitting over 20%.

Anyway, mainly my experience on my driveway gives me a good view of weight distribution and traction.

I don't do much gravel/dirt, but can feel how it also affects that with a few climbs up to canal trails.

Cyclist0108

Sorry, it was in reply to the OP:


I grew up in the Chicago area, born in the adjacent suburb, so I know it is flatter than a witch's ...

DarrinNYC

I don't think even velodrome racers use 21mm anymore. Unless you're averaging 25mph+, the better time had almost nothing to do with tire width; and if you were averaging that speed, the 28mm would likely still be faster.

Myosmith

On the open road, there is more to consider than weight and rolling resistance. I went from 23 mm on a narrow rim to 25 mm on a slightly wider rim and the difference in comfort and confidence has lead to a noticeable increase in overall speed on 20-100 mile rides. Road buzz was reduced and the bike feels much more secure on curves and sketchy surfaces, such as sand kicked or washed up from a shoulder or old rough pavement. In short, the tires might not be faster, but I am because my hands aren't numb and I can keep my speed up in situations where the 23s might feel squirrely.

BTW, on my long rides (50-100 miles) the difference in speed between my road bike with 25 mm tires and my flat-bar mutt bike with 32 mm tires, of the same brand and model, is between 1 and 2 mph on the same route under similar weather conditions. Even with the same bike and the same tires, my rides can vary by 1 mph or more because of slight differences in weather, hydration, or how I'm feeling that day.

TimothyH

The OP had a completely different brand and model of tire mounted on a different wheelset.

Tire width isn't the only thing which changed. It is a completely different setup.

ted ward

+1 on specific tire mattering. My training gatorskins have noticeably high rolling resistance when I run much less than 100 PSI with their stiff/durable sidewalls. Whereas 320 TPI vittoria corsas roll and ride great at the right (low) pressure.

Jax Rhapsody

Hmm... I had a set of 700/23 cst corres that had max pressure of 119, and I ran them at 90, I'd say probably max of 125, which is what 80 bar?

DrIsotope

1 BAR = 14.5psi

90psi = 6.2 BAR
125psi = 8.6 BAR

80 BAR = 1,160psi

Campag4life

Make no mistake, on average there is much more weight on the rear wheel of a road bike. Testament is the fact the rear tires wear out 2-3x's faster than the front.
Wheel slippage is a very small percentage of this difference. Front wheel also turns the bike therefore there is scrub angle in front as well. Difference in wear is due to the weight difference front to rear. The rear shoulders much more of overall weight baring for majority of riding. The butt of a rider can endure much more weight than the hands of a rider on a sustained basis. Why you don't see many 80 y.o.'s on a drop bar bike.

Sy Reene

Do they even make floor pumps for presta valves that don't have pressure gauges? Methinks you'd have to go out of your way to find one.

Wheever

popeye

I'm on Conti Supersonic 20's.

RPK79

I never run less than 1200 PSI. Don't want to get pinch flats.

colombo357

I just use a big solid O-ring instead of a tire, 6mm width.

RPK79

I once set a KOM on a MUP heading back from grinding some gravel with knobby 30s that I haven't come close to beating with my 23s. The science is in.

anon`

McBeth Road and Highway 242 come to mind.

On topic: my bike came with 23mm tires. I switched to 25mm tires. I rode felt faster. And I got faster as the season went on. Now, I'm slower, because I've been lazy this year, and have gotten fat and out of shape. Conclusion: tires help the bike roll, and not slide out in a corner.

Seattle Forrest

One time I heard my brakes rubbing, and was surprised just how much it was slowing me down. Then I looked at the computer and saw I was putting out something like 80 watts. It wasn't the brakes slowing me down.

Humans are natural story-tellers, it's how we related to the world. I changed my tires, and now I'm a lot faster. Maybe. Maybe it was the amount of shampoo he used that day that got him 1 mph. We also have a tendency to change one thing, because we believe it'll be a good change, and then to attribute any good or bad things that happen to it. Finally that also gives us this weird sort of placebo effect, where you expect some change to make you faster, the excitement makes you push harder. A power meter would let everyone know to what extent that last one is at play.