Gears

[deanE]

Saw this on another thread "Have used a gear of 219.29 inches." What does it mean?

 

[guitarpete247]

It is a way of showing how many revolutions the rear wheel goes round and therefore the distance covered by 1 revolution of your crank. Think about the old penny farthing (ordinary). The pedal was connected to the front wheel directly so with a bigger wheel you travel further per pedal revolution. With gears you get the same effect as being able to change the size of the wheel. 219.29 inches is a gear that would be the equivalence of riding with a wheel of that diameter.

 

[HovR]

Basically the higher the number of gear inches, the higher the gear is (harder to pedal, but you'll go faster.)

To put this into comparison, the highest gear on my road bike is somewhere around the 100 gear inches mark.

Here's two links you may find more helpful than my explanation.

Gear Inches: The size of the front wheel needed to achieve that gear if you were riding a penny farthing style bike.
http://sheldonbrown.com/gloss_g.html#gearinch

Development: The number of inches (or meters) the bike will travel for one revolution of the crank.
http://sheldonbrown.com/gloss_da-o.html#development

 

[cyberknight]

Feck me what size legs has that guy got? 219 " , pros max gearing on a stage race is normally 127 "

 

[snailracer]

At 90 pedal rpm, 219 gear inches would indicate 60mph :O

 

[guitarpete247]

I remember a guy on Roy Castle's "Record Breakers" on a bike on stand getting up to something like this speed. I believe he had a single speed with enormous chainring and miniscule rear cog. I can't find a youtube link but I'm sure someone here will either remember it more accurately or know the cyclist's name.

 

[deanE]

Thanks everyone. I now understand. Now where is that tape measure? I think the original quote was a bit tongue in cheek.

 

[Wankelschrauben]

Is that sort of gearing off a drag style bike? The ones where the cyclist drafts a motorbike on a strip?

 

[arallsopp]

I remember a guy on Roy Castle's "Record Breakers" on a bike on stand getting up to something like this speed. I believe he had a single speed with enormous chainring and miniscule rear cog. I can't find a youtube link but I'm sure someone here will either remember it more accurately or know the cyclist's name.

Dave Legrys:
View: http://www.youtube.com/watch?v=q77GMkXzOVE

 

[guitarpete247]

Dave Legrys:
View: http://www.youtube.com/watch?v=q77GMkXzOVE

That's the guy. I knew someone would know it.

232" gear. 126.6mph

Just watched his 110mph on the M42 from 1986. Thanks for remembering his name .