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Gear inches
I have this utterly boring book with a snipit of interesting technical information as a footnote. Quoting;
The calculation of gears is an abiding legacy of the Ordinary (A penny farthing) ...Take the diameter of the rear wheel, mutiply this by the number of teeth on the chainwheel...divide the result by the number of teeth on the rear sproket...you have gear inches. So, counting the cogs I have; Chain wheel Cluser 48 13 snip snip 28 34 which for a 27 inch wheel gives me a range of 100 to 22 inches. It is the 22 inches which interests me as that what I use to stuggle up hills just before getting off to walk. After 6 years of social/group riding, I have *never* heard anyone talk of gear inches, although when thinking about a Rohloff hub, it seems it would be a useful measurement. So I was just wondering if the more profession riders that read this group sit around at night sipping their beer and talking about gear inches, or is it a purely pommy thing from whence this book came? (maybe it's gear centimeters these days?) TIA Owen |
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#2
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Gear inches
It still is a used concept, especially when considering a singlespeed bike. What number is a useful number for SS? I had a 77GI; many people run approx 70GI. Or talking loaded touring: A useful range might be 30-90GI, just what a 11-34 cassette can give if you only have a single chainring as on a folding bike. Or as you suggest, with an internally geared hub it gives you nice insight about choosing the sprocket and chainwheel size to end up with useful range. The other units used are meters development (wheel circumference used instead of diameter) or Sheldon Brown's gain ratio, incorporating crank arm length. The one which seems to be in widespread use is GI. -- jur |
#3
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Gear inches
Owen wrote:
I have this utterly boring book with a snipit of interesting technical information as a footnote. Quoting; The calculation of gears is an abiding legacy of the Ordinary (A penny farthing) ...Take the diameter of the rear wheel, mutiply this by the number of teeth on the chainwheel...divide the result by the number of teeth on the rear sproket...you have gear inches. So, counting the cogs I have; Chain wheel Cluser 48 13 snip snip 28 34 which for a 27 inch wheel gives me a range of 100 to 22 inches. It is the 22 inches which interests me as that what I use to stuggle up hills just before getting off to walk. After 6 years of social/group riding, I have *never* heard anyone talk of gear inches, although when thinking about a Rohloff hub, it seems it would be a useful measurement. So I was just wondering if the more profession riders that read this group sit around at night sipping their beer and talking about gear inches, or is it a purely pommy thing from whence this book came? (maybe it's gear centimeters these days?) I don't know about the professionals, but I started talking about gear inches back in the 70's because that was the only way you could make gearing understood. I still think and talk that way, although Sheldon Brown thinks the writing's on the wall: http://www.sheldonbrown.com/gain.html My 7-speed internal hub gears are set up (by chainwheel and sprocket size) to give me a gear-inches range from 31.38" in first to 95.80" in 7th. John |
#4
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Gear inches
Owen wrote:
I have this utterly boring book with a snipit of interesting technical information as a footnote. Quoting; The calculation of gears is an abiding legacy of the Ordinary (A penny farthing) ...Take the diameter of the rear wheel, mutiply this by the number of teeth on the chainwheel...divide the result by the number of teeth on the rear sproket...you have gear inches. So, counting the cogs I have; Chain wheel Cluser 48 13 snip snip 28 34 which for a 27 inch wheel gives me a range of 100 to 22 inches. It is the 22 inches which interests me as that what I use to stuggle up hills just before getting off to walk. After 6 years of social/group riding, I have *never* heard anyone talk of gear inches, although when thinking about a Rohloff hub, it seems it would be a useful measurement. So I was just wondering if the more profession riders that read this group sit around at night sipping their beer and talking about gear inches, or is it a purely pommy thing from whence this book came? (maybe it's gear centimeters these days?) TIA Owen I think it's still used in racing. For a long time junior track riders weren't allowed to have greater than 100 inch gearing to protect their knees. I don't know if that rule still applies. Friday |
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Gear inches
"Owen" wrote in message ... After 6 years of social/group riding, I have *never* heard anyone talk of gear inches, although when thinking about a Rohloff hub, it seems it would be a useful measurement. So I was just wondering if the more profession riders that read this group sit around at night sipping their beer and talking about gear inches, or is it a purely pommy thing from whence this book came? (maybe it's gear centimeters these days?) If you head down to your local velodrome again it's the only gearing language spoken.....and can't see it dying out anytime soon (rollout measurement in metres seems less 'meaningful', although that is what the juniors are restricted by) Gemma (90inches is my favourite gear) |
#6
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Gear inches
"Gemma_k" wrote in message
... "Owen" wrote in message ... After 6 years of social/group riding, I have *never* heard anyone talk of gear inches, although when thinking about a Rohloff hub, it seems it would be a useful measurement. So I was just wondering if the more profession riders that read this group sit around at night sipping their beer and talking about gear inches, or is it a purely pommy thing from whence this book came? (maybe it's gear centimeters these days?) If you head down to your local velodrome again it's the only gearing language spoken.....and can't see it dying out anytime soon (rollout measurement in metres seems less 'meaningful', although that is what the juniors are restricted by) Gemma (90inches is my favourite gear) Only last week I made up an excel spreadsheet to plot gear inches of all possible combinations of Chainrings (48,49,51,53,54) and cogs (14,15,16) that I got with my track bike.....This gives me a range of 81 to 104.1 inches. I am currently running 81 inches on my road fixie but I am not sure how this translates to the track.....hopefully I will be able to get out next week for my first ride on the new bike. Gags |
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Gear inches
On 2007-01-21, Owen wrote:
So I was just wondering if the more profession riders that read this group sit around at night sipping their beer and talking about gear inches, or is it a purely pommy thing from whence this book came? (maybe it's gear centimeters these days?) I had several long conversation re. gear inches yesterday & today, most likely 'cause I've redone my postie bike as a single speed with a 22t chainring and a 19t cog on the rear. for a grand total of 30ish gear inches. The tiny chainring on the large bike garners a bit of attention :-) (and I almost get two of the require chain lengths from a single store bought lenght of chain) Cheers Joel |
#8
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Gear inches
Gemma_k wrote: Gemma (90inches is my favourite gear) You must be racing indoors |
#9
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Gear inches
"Gags" wrote in message ... "Gemma_k" wrote in message ... "Owen" wrote in message ... After 6 years of social/group riding, I have *never* heard anyone talk of gear inches, although when thinking about a Rohloff hub, it seems it would be a useful measurement. So I was just wondering if the more profession riders that read this group sit around at night sipping their beer and talking about gear inches, or is it a purely pommy thing from whence this book came? (maybe it's gear centimeters these days?) If you head down to your local velodrome again it's the only gearing language spoken.....and can't see it dying out anytime soon (rollout measurement in metres seems less 'meaningful', although that is what the juniors are restricted by) Gemma (90inches is my favourite gear) Only last week I made up an excel spreadsheet to plot gear inches of all possible combinations of Chainrings (48,49,51,53,54) and cogs (14,15,16) that I got with my track bike.....This gives me a range of 81 to 104.1 inches. I am currently running 81 inches on my road fixie but I am not sure how this translates to the track.....hopefully I will be able to get out next week for my first ride on the new bike. Gags Here are some gear charts I modified from the cycling NSW ones, I added a Inch gear table as I am a trackie and somehow I can't bear to for go my years of talking in inch gears. http://users.g-node.com.au/boostlinux/Gear_Charts.xls Here is one you can easy print out on a A4 for use at the track http://users.g-node.com.au/boostlinux/Gear_Charts.pdf On Newcastle 200 meter track I usually ride a 88.7 inch gear, but as I don't currently have a 46 chainring for my new Miche cranks I am using 88.2 I am entered into the Sydney cup on wheels next weekend and will probably be using a 94 to 96 inch gear as the Dunc Gray indoor timber track is quite fast. http://www.nsw.cycling.org.au/files/...7011/07011.htm |
#10
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Gear inches
Owen wrote:
So I was just wondering if the more profession riders that read this group sit around at night sipping their beer and talking about gear inches, or is it a purely pommy thing from whence this book came? (maybe it's gear centimeters these days?) From what I can tell, track riders still talk almost entirely in gear inches. They want to know how far each pedal stroke will take them rather than the specific tooth number I s'pose. -- Bean "I've got a bike You can ride it if you like It's got a basket A bell that rings And things to make it look good I'd give it to you if I could But I borrowed it" Pink Floyd Remove "yourfinger" before replying |
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