gearing question

vs4b
vs4b Posts: 257
edited December 2007 in Road beginners
Hi there,

Bit of a newbie question...

does the gearing on a bike (mines scr2) operate in a linear way, hard to describe what i mean... so middle cog at the front small at at the back is easier to pedal than big at the front and big at the back (which i know you're not suposed to use) ??

does that make sense?

Comments

  • Smokin Joe
    Smokin Joe Posts: 2,706
    It doesn't work like that, it depends on the ratios.

    To work out your gear ratios multiply the number of teeth on your chain ring by the diameter of your rear wheel and divide by the number of teeth on the sprocket. This will give you the size of any given gear in inches.
  • richa
    richa Posts: 1,631
    Inside = Easier/Lower gear. Outside = Harder/Higher Gear
    Rich
  • gkerr4
    gkerr4 Posts: 3,408
    If your SCR is a 9-speed tiagra setup with a triple chainring - i.e. 27 gears in total - there are not 27 'different' gears - it isn't like a 27speed sequential gearbox or something

    there is overlap in the ratios as you move through the front chainrings - and as said in the first response, you need to look at the ratios and turn each combination into 'gear inches' to look for where the overlap lies.
  • vs4b
    vs4b Posts: 257
    ahhh, now it begins to make some sense.

    i was thinking of it as a sequential 27speed gear box... clearly this isn't right, but i'm not sure i can bothered working it all out. i guess i'll just have to experiment unless someone knows the standard gear setup on the scr??
  • willbevan
    willbevan Posts: 1,241
    if your interested I do have an excel spreadsheet that has all the figures and a graph showing the overlap if you want me to email it. PM me if you do

    Will
    Road - BTwin Sport 2 16s
    MTB - Trek Fuel 80
    TT - Echelon

    http://www.rossonwye.cyclists.co.uk/
  • ColinJ
    ColinJ Posts: 2,218
    vs4b wrote:
    ahhh, now it begins to make some sense.

    i was thinking of it as a sequential 27speed gear box... clearly this isn't right, but i'm not sure i can bothered working it all out. i guess i'll just have to experiment unless someone knows the standard gear setup on the scr??
    Just count the teeth on the chainrings and sprockets and put the numbers into Sheldon Brown's gear calculator. Actually, the numbers will be stamped into the metal, though they might be hard to read.
  • Cajun
    Cajun Posts: 1,048
    The following info will probably fall into the category of "Information Overload" :shock: but it should answer your questions.
    http://kenkifer.com/bikepages/touring/gears.htm
    http://www.panix.com/~jbarrm/cycal/cycal.30f.html

    Merry Christmas, and may Father Christmas be very kind to all.
    Cajun
  • John.T
    John.T Posts: 3,698
    Use Sheldon Brown's gear calculator here. Set the gear units to gear inches and ignore the crank length. Just put your chainring and cog sizes in and it will give you all your gear ratios in inches. This figure is the diameter of a penny farthing wheel that would give the same ratio. You will be able to see where the ratios overlap on each chainring.
    http://sheldonbrown.com/gears/
    It is worth bookmarking Sheldon's homepage as he is a mine of usefull info.