benoboy Posted November 2, 2009 Report Share Posted November 2, 2009 Hello there i am doing a University Project where i have to design and build a website, I am going to design a website on the gearing formulas on a bike. 22÷18=1.222 what does the 1.222 mean? does it mean that the lower the number the quicker your going to pedal? and the higher the number the harder it is to pedal??(20 x 18) ÷ 12 = 30(26 x 20) ÷ 17 = 30.588why is the 26(stock) more stiffer???sorry if i sound dumb.are there any more formulas i dont dont about?thankyou ben Quote Link to comment Share on other sites More sharing options...
Revolver Posted November 2, 2009 Report Share Posted November 2, 2009 The number means how many times the rear wheel will go round for one rotation of the crank.1.2 is low, 1.8 is hard, for example.Stock gears are lower because the wheel is bigger, which means to get the same motion out of a mod, a higher ratio is needed. Quote Link to comment Share on other sites More sharing options...
forteh Posted November 2, 2009 Report Share Posted November 2, 2009 The 1.222 is purely a ratio, it should be 1.222:1 meaning that for every 1.222 turns of the cranks the rear wheel turns 1 times. I find it a bit concerning that someone at university doesnt know what a ratio is though Depending on how much detail youre going into, you also need to take into account crank lengths and wheel diameters Quote Link to comment Share on other sites More sharing options...
Luke Rainbird Posted November 2, 2009 Report Share Posted November 2, 2009 The 1.222 is purely a ratio, it should be 1.222:1 meaning that for every 1.222 turns of the cranks the rear wheel turns 1 times. I find it a bit concerning that someone at university doesnt know what a ratio is though Depending on how much detail youre going into, you also need to take into account crank lengths and wheel diameters You might want to rethink which way round that ratio is before calling him someone out on it though Wheel diameters affect the required ratio, crank length is purely a question of leverage. Quote Link to comment Share on other sites More sharing options...
benoboy Posted November 2, 2009 Author Report Share Posted November 2, 2009 (edited) thankyou so much. just another quick question.what does this table mean? what does the numbers in the middle of the table represent? what is the magic number?http://43-bikes.the-up.com/mechanics-corne...nd-26-t2653.htmthis is the last question! thankyou very muchBen Edited November 2, 2009 by benoboy Quote Link to comment Share on other sites More sharing options...
forteh Posted November 2, 2009 Report Share Posted November 2, 2009 You might want to rethink which way round that ratio is before calling him someone out on it though Minor detail Quote Link to comment Share on other sites More sharing options...
sstein Posted November 2, 2009 Report Share Posted November 2, 2009 thankyou so much. just another quick question.what does this table mean? what does the numbers in the middle of the table represent? what is the magic number?http://43-bikes.the-up.com/mechanics-corne...nd-26-t2653.htmthis is the last question! thankyou very muchBenIt is a way of working out how many teeth you should have on a driver for street riders. To be honest it seems like quite a flawed system as it does not appear to have a ratio system and because of this it all means very little, however the numbers can be compared to see what equivalent drivers would be like, for instance an 11/12 tooth driver on a 26" would be roughly equivalent to an 8 tooth driver on a 20" providing you use the same size chainring. (Unless I am mistaken) Quote Link to comment Share on other sites More sharing options...
meony Posted November 2, 2009 Report Share Posted November 2, 2009 You also have to consider the wheel diameter as this will greatly effect the distance the gear actually propels you :26 inch in one revolution will travel along the ground further than a 20 inch will. I think this is the relevant equasion. Front sprocket- Divide by rear sprocket- Multiply rear wheel size.The lower the product number the shorter the total distance traveled, the easier the gear.Hope this helps, Meony. Quote Link to comment Share on other sites More sharing options...
duncan_echo26 Posted November 2, 2009 Report Share Posted November 2, 2009 (edited) If you multiply 1.2 (22 teeth/18 teeth or 18 teeth/15 teeth) by the circumference of the wheel (26 inch wheel-26xPi) you will get 81.681 which means in one turn of the cranks you will travel 81.681 inches.If you multiply 1.5 (18 teeth/12 teeth) by the circumference of the wheel (20 inch wheel-20xPi) you will get 62.832 which means you will travel 62.832 inches in one turn of the cranks.Obviously the size of the tyre etc. could make a difference but it would be so small it wouldn't be noticeable.Also to find the 'Gear Inches' use: (Number of teeth at cranks/Number of teeth at hub) x Wheel diameter = Gear inchesGear inches is different from the distance you travel in one turn of the cranks because it uses the diameter of the wheel instead of the circumference.Sorry this post was wrong before so I edited it. Thanks Luke Rainbird for pointing out I was wrong Edited November 2, 2009 by duncan_echo26 Quote Link to comment Share on other sites More sharing options...
Luke Rainbird Posted November 2, 2009 Report Share Posted November 2, 2009 Technically you're not travelling 32 or whatever inches per revolution, you'd need to multiply by the wheel circumference for that, but you're only a factor of Pi out which'll be the same for each wheelsize Quote Link to comment Share on other sites More sharing options...
duncan_echo26 Posted November 2, 2009 Report Share Posted November 2, 2009 Technically you're not travelling 32 or whatever inches per revolution, you'd need to multiply by the wheel circumference for that, but you're only a factor of Pi out which'll be the same for each wheelsize Thanks I never thought of that before I will edit my post Quote Link to comment Share on other sites More sharing options...
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