Single speed bikes.

[croyde]

What are the usual amount of teeth on the front and rear cogs on a typical single speed?

I just want to emulate the gear on my 24 speed to see what it is like.

Cheers.

 

[hubgearfreak]

i use 48/18 on a 27x1 1/4 wheel & tyre.

however, you're going the wrong way about it. ride around for a day in a gear that you can ride around for a day in, then re-produce that in a single speed bicycle.

you could ride your geared bike around permanently in one gear, but it won't be as quiet, light, efficient or as aesthetically pleasing as a single speed.

 

[croyde]

Cheers and my hybrid is on 26 inch wheels so another factor.

Good call, Ta.

 

[RedBike]

It doesn't work like that. SS bikes are more efficient so you'll get away with a much higher gear; and it's suprising just what gear you can climb a hill in when you haven't got the option of changing down.

 

[kyuss]

Here is a great gear calculator, that takes wheel size, tyre width, crank length etc into consideration when working out gear size. I think most off the peg singlespeeds come with a gear of around 68-72 inches. I'd aim for the lower end of that if singlespeed, the higher end if running it fixed gear as they tend to be a bit easier to climb with and you wouldn't want something so small you're spinning like a washing machine on the downhills.

 

[hubgearfreak]

and another calculator. http://www.sheldonbrown.com/gears/

around 68-72 inches.

is good advice, anywhere in that range will do, obviously it's only going to be right some of the time, so it doesn't really matter

fixed ... they tend to be a bit easier to climb with

why do you say this?

 

[MajorMantra]

why do you say this?

There's no 'deadspot' as you pedal. The forward motion of the bike keeps your legs turning through the top of the pedal stroke making it easier to keep going up a hill.

Matthew

 

[hubgearfreak]

ah, the old flywheel effect myth.

if the kinetic energy stored in the mass of a moving bicycle and rider were to drive the legs of said rider past TDC, then that's at the expense of the aforementioned kinetic energy.

so effectively you leg brake up hill, and that makes it easier?

 

[MajorMantra]

ah, the old flywheel effect myth.

if the kinetic energy stored in the mass of a moving bicycle and rider were to drive the legs of said rider past TDC, then that's at the expense of the aforementioned kinetic energy.

Yes, but since it makes you more efficient overall you still benefit.

Matthew

 

[hubgearfreak]

please explain?

 

[MajorMantra]

It's late and I lack the energy. This effect is well explained elsewhere and easily observable if you ride a fixed gear and compare it to a freewheel bike when climbing.

Matthew

 

[kyuss]

please explain?

I have neither the vocabulary or scientific knowledge to explain. I think anyone who has ridden fixed gear for any length of time would agree with the statement though. It's not a massive difference but it's real and tangible. I noticed an improvement in hill climbing when I moved from singlespeed to fixed with the same gear setup.

It's magic I think, or fairies or something. You could just try riding one and see for yourself.

 

[hubgearfreak]

if you ride a fixed gear

You could just try riding one

so in the absence of an explanation, you both suggest i simply try it? very good.

now, can i suggest that you fit a free-wheel to your fixeds and try some hills?

i have tried it, and i must say that theory and practice converge, both in theory and in practice. there's no difference to be observed, as theory tells us.

it's a myth chaps, please either state an explanation or stop peddling nonsense

 

[Pottsy]

The whole momentum of you and your fixed wheel bike drive the wheel, hence chain, hence cranks and ultimately your legs through the flat spots at the top of each stroke. It feels smoother and quicker.

However I agree this doesn't scientifically explain the benefit over a single speed being constantly pedaled.

Perhaps its all the additional weight of the bearings in the free wheel that slow you down.

 

[hubgearfreak]

feels smoother and quicker.

you're right, it may feel so to some, but there's no theory or demonstrable evidence to prove it. like god/religion really.

the additional weight of the bearings in the free wheel that slow you down.

that will make a difference.

lets say 50grammes for a 100kg bike & rider. is that 1/20 of 1%?