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-   -   Smaller Wheels = Better Acceleration? (https://www.bikeforums.net/folding-bikes/962445-smaller-wheels-better-acceleration.html)

 Kevin Backalive 07-29-14 10:32 AM

Smaller Wheels = Better Acceleration?

Is it true that smaller wheels, let's say 20" offers better acceleration whereas Bigger Wheels offers higher Top Speed?
And does Smaller Wheels climb road better? :)

 tdong 07-29-14 11:09 AM

Everything is still depend on the engine which is you. different bike use for different purpose.

 bikemig 07-29-14 11:13 AM

https://www.bikefriday.com/bicycles/small_wheel_myths

 tds101 07-29-14 11:54 AM

All depends on the sprockets/cogs & the engine powering the wheels. I can get pretty much the same speed on all my bikes.

 fietsbob 07-29-14 12:28 PM

Kevin , climbing a hill is working against Gravity , are you wanting to go faster as you climb the hill you shift to a harder gear..

to go fast the air had to be pushed out of the way..

Mass at rest takes energy to accelerate it. weigh everything.. its math .. go for it. calculate .. Newton is a start.

'gear' is a ratio x wheel diameter , same gear F:R in a smaller wheel is a lower one..

Heavy duty tube + puncture resistant tire of small diameter , Vs the super light rims and tires on a pro racing bike though larger

too many variables for a Blanket Generalization ..

 jur 07-29-14 02:23 PM

Acceleration is better on small wheels. Simple physics.

 fietsbob 07-29-14 02:40 PM

Physics is Math, the heavy small vs light and larger . got the calculations on that?

 smallwheeler 07-29-14 02:59 PM

Quote:
 Originally Posted by jur (Post 16986406) Acceleration is better on small wheels. Simple physics.
Quote:
 Originally Posted by fietsbob (Post 16986473) Physics is Math, the heavy small vs light and larger . got the calculations on that?
http://s2.quickmeme.com/img/7f/7f0ce...01b13f2676.jpg

 dynaryder 07-29-14 04:07 PM

1 Attachment(s)
Srsly. :rolleyes:

Hay FeetsBob,ever see these?
http://bikeforums.net/attachment.php...hmentid=396202

 fietsbob 07-29-14 05:12 PM

Meh, who cares.. :roflmao2: wheres the frickin spokes ? .. 406-47 on 32 hole .. CR 18are bomb-proof

the lower mass + short trail have some complaining about 'twitchyness' .. cant please everyone..

set them all side by side, stand back and see which one moves first

 cplager 07-29-14 05:39 PM

Quote:
 Originally Posted by jur (Post 16986406) Acceleration is better on small wheels. Simple physics.
If it were the wheels by themselves, it would depend on the weight, not size (light 700 c wheels would accelerate faster than heavy 20" wheels).

All that being said, the weight of the wheels is almost irrelevant compared to the total weight of the system (rider + bike + wheels).

Or, as correctly posted above, it's the engine.

 tds101 07-29-14 05:45 PM

Choo-Choo!

 jur 07-29-14 06:41 PM

Not just the weight of the wheels but more importantly the moment of inertia. For two wheels of identical weight, one 700c and the other 20", most of the mass is concentrated at the rim. Therefore the 20" wheel has a much smaller moment of inertia, which is a function of radius squared. Hence faster acceleration. Simple physics.

 smallwheeler 07-29-14 07:01 PM

from an ancient, dust-covered thread entombed in the sands of time (but, readily available because: the internet- where nothing ever truly dies). suitable entertainment whilst devouring the best nasi goreng you've never tasted:

https://i.imgur.com/KfbyDFS.png

Quote:

 keyven 07-29-14 07:26 PM

Quote:
 Originally Posted by jur (Post 16986406) Acceleration is better on small wheels. Simple physics.
Pretty much this.

Someone asks a simple question and ends up with a dozen complicated answers.

It's like they suddenly turn to one another and start discussing astrophysics - at least to noobs like me. Sometimes generalization is good.

 cplager 07-30-14 04:55 AM

Quote:
 Originally Posted by jur (Post 16987158) Not just the weight of the wheels but more importantly the moment of inertia. For two wheels of identical weight, one 700c and the other 20", most of the mass is concentrated at the rim. Therefore the 20" wheel has a much smaller moment of inertia, which is a function of radius squared. Hence faster acceleration. Simple physics.
tl;dr: You're wrong. And you're wrong.

Do the math. If the weight distribution of the wheels is the same (e.g., the mass is all at the edge of the wheels - not a bad approximation if you drop the mass of the hubs), the radius drops out of the energy equation. So, it's the weight of the wheel, not the size that matters. (Hint -bigger wheel spins more slowly for the same linear speed)

And again (and most importantly), you're not just accelerating a wheel, your accelerating wheels, a bike frame, and a rider with her stuff. So, even if the wheels were lighter, it would hardly matter.

Saying "simple physics" over and over doesn't do anything useful (except possibly convince us about you except how little attention you paid in your high school physics class).

 cplager 07-30-14 04:58 AM

Quote:
 Originally Posted by keyven (Post 16987286) Pretty much this. Someone asks a simple question and ends up with a dozen complicated answers. It's like they suddenly turn to one another and start discussing astrophysics - at least to noobs like me. Sometimes generalization is good.
That's great and all. But it's wrong.

I like the KISS principle, but keeping it so simple that it is wrong isn't helpful.

If you don't want to do the math yourself, at least listen to somebody who did.

 chagzuki 07-30-14 05:39 AM

This is a laugh.
I have to say, what seemed simple when unformulated in my head seems more complex as I try to picture all the factors.

And I can't be bothered.

But yes, small wheels accellerate faster, and that's what provides the fun factor.
At traffic lights on the brompton I shoot off in front of all the regular sized bikes and then shortly after the roadies overtake me and I watch them slowly recede into the distance.

 keyven 07-30-14 08:09 AM

Quote:
 Originally Posted by cplager (Post 16988175) That's great and all. But it's wrong. I like the KISS principle, but keeping it so simple that it is wrong isn't helpful. If you don't want to do the math yourself, at least listen to somebody who did.
Ok fair enough. I like simple too, but I guess I was looking at it the wrong way.

 prathmann 07-30-14 08:24 AM

Quote:
 Originally Posted by cplager (Post 16988168) tl;dr: You're wrong. And you're wrong. Do the math. If the weight distribution of the wheels is the same (e.g., the mass is all at the edge of the wheels - not a bad approximation if you drop the mass of the hubs), the mass drops out of the energy equation.
I think you meant to write that it's the radius of the wheel that drops out of the energy equation - the mass definitely stays in. And tends to be smaller if the wheels are smaller with the same type of construction. While I agree that the wheel mass is such a small part of the total that it doesn't affect the overall speed or acceleration much, it's a part that is felt quite easily by the rider when starting up and the bike is being tilted from side-to-side and also steered back and forth a bit. So there's a different feel to a bike with light wheels.

 cplager 07-30-14 05:10 PM

Quote:
 Originally Posted by prathmann (Post 16988621) I think you meant to write that it's the radius of the wheel that drops out of the energy equation - the mass definitely stays in. And tends to be smaller if the wheels are smaller with the same type of construction. While I agree that the wheel mass is such a small part of the total that it doesn't affect the overall speed or acceleration much, it's a part that is felt quite easily by the rider when starting up and the bike is being tilted from side-to-side and also steered back and forth a bit. So there's a different feel to a bike with light wheels.
Um whoops. Yes, the radius drops out leaving only mass.

Whether or not you can feel the difference between light wheels and heavy wheels is another question entirely...

 iFold 07-30-14 09:39 PM

There are many factors concerning acceleration. My skateboard doesn't accelerate faster than my 20"er, on a rough road. :p

But all else equal except wheel diameter, then the smaller wheels has better acceleration than bigger wheels due of course to wheel diameter. You can complete a pedal stroke (single revolution) easier on small wheels.

 cplager 07-31-14 04:54 AM

Quote:
 Originally Posted by iFold (Post 16990985) But all else equal except wheel diameter, then the smaller wheels has better acceleration than bigger wheels due of course to wheel diameter. You can complete a pedal stroke (single revolution) easier on small wheels.
You're talking about hearing differences, not things inherent smaller wheels. (My 26" wheeled bike is geared (very slightly) lower my 20".

 fietsbob 07-31-14 12:02 PM

Quote:
 does Smaller Wheels climb road better?
the work is getting You , and the bike, up the Hill . the smaller wheel really wont help or harm .. the gravity pull remains the same.

tell us about the hills on your island. Kevin .. (you still there?)

a sprint from a stop sign on the flats is another situation entirely , though not really its the Mass of You and the bike
you have to accelerate .

that is the same Newtonian situation. taking a Body at rest into a body in motion..

start in a Low gear and upshift as you over run the gear, and either will move you ahead fast enough.

 mconlonx 07-31-14 12:18 PM

It depends.

In a perfect world, because math and physics, the same person applying the same amount of force after overdrinking the same amount the night before should theoretically be able accelerate small wheels faster.

However, we don't live in a perfect world and we really don't care about wheel acceleration, do we? No, we don't: we care about how fast we can accelerate ourselves. Assuming we did not overdrink the night before, in which case we don't really care about the acceleration characteristics of different diameter wheels, and only vaguely about how fast we can accelerate ourselves, usually maxing out somewhere south of the PukeLevel of exertion.

Try this test: go to the the beach with a high-performance 20" (451) wheel running 23mm wide tires pumped to 120psi. Also bring along a fatbike with 26 x 4.8" tires set at 8psi (note, actual diameter on these can be larger than most 29" wheel/tire setups). In deep, loose sand, you will probably accelerate the wheels of the 20" bike faster; you will accelerate yourself faster on the bike with much, much bigger wheels/tires.

In any case, bring along a pitcher of bloody mary you mixed up before you left for the beach test -- because of the overdrinking the night before, you will need it, and because you did this physics test on the beach after a night of overdrinking, gosh-darnit, you deserve it.

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