dalegribble

I commute on a Trek SS Beach Cruiser. Although heavy, its very comfortable. I wanted to change the tires out for something with a little narrower width. Currently it has 26x2 on matrix 550 wheels. I was wanting to do something like a 26x1.75 Continental Urban but didnt know if I'd need new tubes or not. Maybe someone can recommend another alternative?

Additionally, is anyone running offsets (thinner in the front, thicker out back) tires. Basically im trying to pick up less rolling resistance. I will eventually buy a hybrid but just dont have the funds currently.

Wolfwerx

If it were me, I wouldn't rush out and buy new tubes. What you have will work. When you need to buy replacements, down the road, then pick up the size that corresponds with whatever tire you end up with.


As for "less rolling resistance" you can get some good slicks/ street tires in 1.75-1.85 that wouldn't look bad on your bike and may be a little quicker on the road, but I doubt anything is going to make a difference on a heavy cruiser in any real meaningful way.

rumrunn6

go directly to a road bike, maybe with straight bars.

clarkbre

If the wheels allow, I would step down to maybe a 26x1.5. A 1/4" change is good but not as noticable as dropping a full 1/2" in the tire width. If you can find a tire that you can keep around 80psi, the change (lack of) rolling restitance will be very noticable.

dwinks

Skinny tires are slower than fat ones, especially if the skinny tires are higher PSI.

The "skinny tires = faster" misinformation was caused by a few things, one of which was the fact that skinny tires beat the heck out of you on the road, making slower speeds FEEL faster. The other was from a series of tire-against-steel drum tests, which proved that a hard, skinny tire WITHOUT a bike and rider above it was lower rolling resistance. When tested with a rider on board, on real roads (even super super smooth ones), fatter tires (between 1.75 and 2.0 in 26" sizing, 42-47mm otherwise) were always faster.

The difference in air resistance between a skinny tire and a fatter one is nearly immeasurable. Weight difference is noticeable, but only in sprints. Rotational inertia only matters when accelerating. A skinny tire doesn't absorb shocks from the road, and instead transmits them to the bike and rider. This not only feels awful, but it slows you down, considerably. Jan Heine performed some tests riding a bike on the rumble strips on the side of a highway at one point and found that it took THREE TIMES as much energy to maintain speed. He also found that even on the smoothest of smooth roads, the road was still rough enough that the losses from high-pressure skinny tires made them slower than fatter tires. That's right, even the smoothest road was rough enough that a fat tire rolled faster.

Bottom line: don't worry about the width of your tires. Casing, tread, construction, etc matter far more than width. Something like Schwalbe Big Apples in 2.0 would give you just about the lowest rolling resistance you can get on this bike. Narrower WILL slow you down. Especially on an upright bike which has more "suspension losses" (the term used to describe losses in energy from hard, narrow tires transmitting road shocks to the bike/rider), since you will be putting more weight on your rear and less on "sprung" parts like your feet and hands (which can more gently absorb shocks by "un-weighting").

Read more here:https://janheine.wordpress.com/2010/1...-and-pressure/

clarkbre

Yes, scientifically skinny, highpsi tires may roll slower…

However, where the rubber meets the road (very literally),is a different story. It’s all aboutavailable energy and resistance. Take tiresA and B (A=26x2.0@40 PSI B=26x1.5@80 PSI) mounted on a bike that weighs30 pounds with a 170 pound rider. Withthe weight of the bike and rider, Tires A may have a contact patch of 10 squareinches each. However, Tires B have acontact patch of 6 square inches. Inturn, Tires B have a 40% smaller contact patch on the ground allowing 40% lessenergy from the cyclist to turn the tires at the same speed of Tires A. The 40% of energy saved from not having topush Tires A can be converted into more efficiency. This allows the cyclist to move the bikeequipped with Tires B at the same speed as Tires A using much less energy. The saved energy also allows the cyclist touse different gearing which can help create higher speeds with Tires B asopposed to A.

So…yes, a skinnier, higher psi tire may roll slower but takeinto account all parts of the equation.

BassNotBass

I agree with this. Materials and construction are more important than width. Big Apples and even Fat Franks are deceptively fast tires.

*Here's some interesting reading of something that really goes against the grain of popular thought. Also Alex Moulton addressed the issues pertaining to thin high pressure tire's shortcomings with suspension fore and aft.
https://www.moultonbicycles.co.uk/her...#recordsracing

Wolfwerx

How do you arrive at this calculation? Does area directly relate to work at a 1:1 ratio? I doubt it.

Show your references, please.



Edited to add:
Additionally, tire composition plays a part as well as road/surface conditions.
Say you have a 1.5" wide knobby and a 1.5" wide slick tire... the contact area from the knobby will be less than the slick, but it will require more work to spin on the road.

dwinks

That just isn't how it works. First, barring some (minor) losses of contact patch size caused by sidewall stiffness, 40PSI tires (regardless of width) will have a contact patch of 10sqin TOTAL. Bike + rider = 200lbs, 200lbs / 2, since there's two tires = 100lbs per tire (a bit more in rear, depending on bike, usually). 100lbs / 40lbs/sqin = 5 sqin of contact per tire. An 80PSI tire would be 2.5sqin each. Thankfully, under normal circumstances, the addition weight per sqin on the higher PSI tires cause them to have approx the same grip on the road. However, as they have half the area on the road, they have half the chance of maintaining that grip on slick areas. If 3sqin of tire contact slips on the skinny tire, you go down. If 3sqin of the fatter tire are on something without grip, you still don't slip since there's 2 more sqin to hold. Fatter tires also don't get caught in rail tracks, grooves, bridges, etc.

Now, here's the kicker, the fatter tire will have to have significantly less drop (deform to flatten against the road) to deform the tire at the contact patch, and if all else is equal (casing, construction, rubber compound, etc), the fatter tire will lose less energy from this deformation. Combine this with the fact that a fatter, softer tire will deform more easily on road bumps, rather than sending the shock of road bumps and holes to the bike and rider and you end up having less total energy losses at normal cruising speeds. Every time you feel a bump or even vibration on your bike, that's energy that USED to be carrying you forward, but is now being lost as shock and vibration. Fatter tires can simply roll over a lot of smaller bumps, have the tire deform around the bump and continue forward with minimal losses. A skinny tire will buck the bike and rider upward on the same bumps, losing a LOT more energy (and being annoying/painful). Because fatter tires roll over so much of the road irregularities, they feel much smoother. Skinny tires transmit all of that as vibration and shock to the bike and rider, which make them FEEL faster, since the road is beating you up more.

Fatter tires weigh more, which is important in road races with LOTS (not more some, but basically constant) attacking and acceleration. Constant, rapid, all-out acceleration doesn't occur on anything approaching a normal ride. Fatter tires are also wider and have more air resistance, however due to the exponential way speed affects air resistance, this only matter above about 30MPH or so...as the difference between a 21mm tire and a 23mm tire and a 25mm tire is almost un-measurable. The difference between a 26x1.25 and a 26x2 is more, but still not a factor at anything under 30mph, at least not one that's measurably significant.

I ride on 26x1.85 tires (ISO 559x47) and my commute speeds average around 18-21MPH depending on direction, wind, and temp. If I ride without really trying, I still average 15-18, and that's at a "leisurely" pace. My 47mm wide tires definitely don't slow me down. They are also pretty much flat-proof, comfortable, and safe. Bottom line, there's no way in hell I'd be going 40% faster if I had different tires.