nz6666

Note I am not saying small wheels are slower. I know it's the gearing. A small wheel can be as fast as or faster than a bigger wheel if using higher gear (assuming other factors are the same, e.g. same person, same gear, same road etc). But would that mean the person on a small bike have to use more effort to keep up at that speed because of higher gearing? If this is true, so the person on the small wheels will get tired earlier/more easily than the person on the bigger wheels?

I am asking because I use my folder for commuting everyday, I cycle 7.5 miles one way on the folder from the train station. If I cycle from home that is 15 miles one way. I haven't done the whole route using my big bike so just wondering will I be more tired after 15 miles on my big bike? I know I need to have a try but just wondering what you guys think in theory?

tdong

between my Dahon mu sl and Kestrel Pro 4000. I don't see a any different in speed when I put the same effort. However when i ride the Kestrel, my brain is telling me that you are riding a race bike put more effort into it. So for the same distance i usually ride 40km. I felt more tire when I used my kestrel vs my dahon . I am only riding for exercise what do i know hehehhe

rhenning

It on paper should be less effort. Two main reasons given equal quality wheels and hubs. Small wheels should be less weight and second require less effort to over come centrifical force needed to spin the wheel. In my case I have a Bike friday Pocket Rocket and several equal quality road bikes and the Friday is easier to get up to speed. Roger

LWaB

Rolling resistance is greater with small wheels but wind resistance is somewhat reduced. For several years, my partner and I have ridden lots of brevets of between 200km and 1200 on both 406 and 622 wheels. There is negligible difference in road speed but our riding positions are identical, whether on little or big wheels.

qclabrat

from my experience on my Llama, the flats are comparable to my 700c road bikes, but climbing is another story. going to a lower gear in the front requires me to almost spin twice as fast than the other bikes

Ozonation

That's my experience too.

cplager

Please stop confusing gearing issues with wheel size.

I've got a 26" wheel bike with gear range from 16" to 107". I've got a 20" wheeled bike with gear range from 17" to 106".

There's almost no difference in speed between these bikes (and when there is, it's tire choice, not wheel size that has been the decisive factor).

So, yes, if you don't have the needed gear range, it won't work as well for you. Wheel size has very little effect otherwise on (mostly) smooth roads.

nz6666

Gear inches formular: [chainring] / [cog] * [rear tire effective diameter measured in inches]

So if two bikes (big and small wheel) are at the same speed, that must means small wheel bike using a higher gear, so that means more effort, right? I am talking theory only. I know in practice other factors can never be the same so it's hard to compare. And lot of you are still talking about speed, I am talking about effort spent though. In theory, if there is a crazy gearing on a insanely small wheeled bike, it can still beat any bike in terms of top speed, but it sure takes tons more effort to do that, no?

tdong

no the same effort with everything else constants.

fietsbob

I'd only worry about Time on the way in , so you dont get sacked for poor Punctuality , missing your Train connection , etc.

on the way home enjoy the ride & the miracle of your existence in time and space.

Ozonation

We should rename this the Folding Bike and Life Philosophy Forum!

ThorUSA

its for me ...

cplager

Yup.

1nterceptor

You don't mention what type of folder you have; and which big wheel
bike you're comparing it to. Some folders are designed for fast riding
while others are concerned with weight, compactness, etc. Big wheel
bikes come in many flavors as well; mountain, touring, road, etc. My
Brompton was designed with taking up as little space as possible. My
roadbike(2014 BMC GF02) was designed to be quick and comfortable
on long rides. I have done over 100 mile rides on both and was faster
and more comfortable with the roadbike. in this video I'm passing all
of the bikes at the 35 mile point of a 40 mile ride. Not sure if I'm using
more energy than them or just have better gearing for that uphill section

https://www.youtube.com/watch?v=lmFU...aIoDLA&index=7

thugpipe

If two bikes are traveling at the same speed one with big wheels and one with small and each have the appropriate gearing to translate into the same distance covered per pedal stroke then all else being equal you should be expending the same effort on each to acheive the same speeds. This is because essentially the two bikes are geared the same, gear inch calculations take wheel size into account for a reason, in essence your wheel is just another gear. When you talk about the small wheeled bike needing a taller gear you are only talking about one part of the system but taking into account the whole system the two bikes would have the same gearing and if you are pushing the same weight with the same gearing its the same thing unless one had a massivly more convoluted gearing system with more cogs and chains to add drag.

If a bike takes more effort to achieve or maintain a given speed than another then it is not "just as fast" a bike, it is a slower bike the rider would just have to be spectacularly strong to make it seem faster.

nz6666

Can't understand how do you get the same effort conclusion. For example, to get the same gear inches (hence same speed or distance per pedal stroke) on both bikes the small bike has to use a bigger chain ring and/or smaller rear cog due to the smaller diameter of the wheels. Any of these (bigger chain ring, smaller rear cog) translates to more effort right? It's like you are riding then suddenly switch to a higher gear (front or rear) then you must spend more effort.

cplager

If you put crank length into the gear inch calculation, you get mechanical ratio out. In other words, riding two bikes with the same gear inches and the same cranks, you are pushing equally hard on the pedals to maintain a given speed (assuming the same aerodynamic drag and ruling resistance).

Not the most easily parsable sentences ever written, but everything you need to know is in there.

energyandair

You are missing the smaller size of the wheel.

The purpose of the larger chain ring and/or smaller rear cog is to offset the smaller rear wheel and end up with the same distance down the road for each rotation of the pedals and chainring. Same distance, same effort.

fietsbob

Air resistance is the same at a given speed-constant, no matter what the wheel size is ..

to be more similar, a tire of the same construction and width only differing in diameter would be in your comparison test.

Azreal911

you also have to take into account the smaller wheel, with a smaller wheel and the same gears as a big wheel bike then it's like you are switching to a LOWER gear and you expend LESS effort. So higher gear on the chainring and rear cogs would only EQUAL it out not make it harder.

thugpipe

My point is that a gearing ratio is a gearing ratio. You are acting like there are only two components making that up, the chainring and the rear cog but you are not factoring in the wheel. All the wheel does is shift your gearing ratio so you compensate with different gears to get the same overall ratios.

My mini velo has 20"×1.95" tires and 56t chainring and an 11t rear cog which equals 99.83 gear inches which means that every time I rotate the crank one full rotation I move the vehicle forward 99.83".

I take a road bike with 700c 25c wheels+tires with a 53t chainring and a 14t rear cog which in turn has 99.87 gear inches and rotate the cranks one full rotation the bike will move an almost identical distance forward as the 20" wheeled bike. If the two bikes+riders weight the same and the tire inflation was adequate to have similar levels of rolling resistance the two bike would require the same effort to move the same weight the same distance.

When you change gears on a bike to a bigger gear or smaller cog it gets harder or more effort because it is a different ratio not just because the cog is bigger or smaller.

nz6666

Thanks for the explanation. I understand the gear ratio and gear inches. But I was thinking same gear inches only means same speed not necessarily same effort so I asked whether the higher gear ratio on small wheels means more effort. But it seems you all think same gear inches means the same effort. I am still not convinced on this although I tend to agree with you.

thugpipe

Well your initial question was centered around gearing. There are many other factors that go into effort and all those are dependant on the individual bike, hell I have two near identical minivelo and they feel quite different in the level of effort needed to maintain a given speed (I am working on that btw). Really tire choice/inflation level, bike+rider weight, drive system type, rider fit, and quality of setup are far more important. I really think all these things have a greater effect on effort put in than just the wheel size I personally take it on a bike by bike basis, you really can't just put it all on one feature, there are just too many variables.

cny-bikeman

NO, for two reasons:

1. A bigger chainring or smaller cog does not matter if the gear inches are the same. The larger chainwheel is only "harder" if you keep wheel size the same.

2. A higher gear is not necessarily "harder." It requires more pedal pressure but a smaller distance (fewer rev's) to do the same work. That may be more or less biodynamically efficient.

Sixty Fiver

The gearing on my Moulten (16 inch wheels) and P20 (20 inch wheels) is very close to that of my touring bike which rolls on 26 inch wheels, the riding positions and weight of each bike is very close.

It is not quite apples to apples but for practical purposes, I think things are fairly close.

I do not notice a lot of difference between these bicycles, the P20 is a little quicker while the Moulten has the best ride quality, and the touring bike handles really bad roads better than either.

The folder and the Moulten are not as fast as my road bike since they are heavier and do not run as high a top gear so I cannot exploit tailwinds and descents, a folder that had the same set up and weight as the road would perform as well and with a small wheel there is an aerodynamic advantage because of less frontal area, and weight advantage because they use less material, and they accelerate faster.