chain ring / sprocket ratios (again)

[JT71]

there was a really useful thread about this before, think it went down with the previous new school section.   

basically, if I'm using an 11t cassette driver on the back what do I want up front.

park and street and popping to the shops. 

[zed4130]

i did put up a site with a good chart before, wish it was kept as a sticky, ill see if i can find the site 

paul

[zed4130]

not sure if this helps  as only runs to 12  isnt it 11-30 ?
http://rocketbmx.com/Merchant2/merchant.mvc'screen=CTGY&Store_Code=RB&Category_Code=xC

[perry]

http://www.bmxultra.com/downloads/flash/gearchart.htm

make a note of the ratio and then have a play  ( higher ratio means harder to pedal  )

[zed4130]

thats a cool chart perry, ive saved that now, so 30-11 is kinda normal then, mine is 33-12 

[JT71]

thanks for the help chaps, the chart would be a good technical sticky,

30 it is...if i win the wheel on evilbay that it. 

[dodgydave]

this what was on the last thread...if its any help ..

44/16
39/14
36/13
28/10
25/9

[Dark Diggler]

In old money 44/16 with 20" wheels represents 55" gearing.

the equation for any size wheels is:  Front cog divided by Rear cog multiply by wheel size I. E   44 Div by 16 (2.75) multiply by 20 - 55" gearing

The higher then end number the harder you gearing will be.

My jump bike has 24" wheels and runs 25/11 so is pretty close to 44/16 bmx gearing at 54.55" gearing


SIMPLE 

[zed4130]

In old money 44/16 with 20" wheels represents 55" gearing.

the equation for any size wheels is:  Front cog divided by Rear cog multiply by wheel size I. E   44 Div by 16 (2.75) multiply by 20 - 55" gearing

The higher then end number the harder you gearing will be.

My jump bike has 24" wheels and runs 25/11 so is pretty close to 44/16 bmx gearing at 54.55" gearing


SIMPLE 

yeah just as he said   

[Gary72]

if you win the wheel, Stevie B has some lovely 30t Colony sprockets. £20 posted

[pickle]

they sure are nice!! 

[zed4130]

that does look nice rob , 

[SaMAlex]

the equation for any size wheels is:  Front cog divided by Rear cog multiply by wheel size I. E   44 Div by 16 (2.75) multiply by 20 - 55" gearing

Almost right but the "wheel size" needs to be the "wheel Circumference". (Put a tyre on a wheel and measure the outer Circumference and I bet it aint 20" (or 24" for a cruiser wheel)).

Then the number you end up with (ie 55") is the distance the bike will travel in one turn of the cranks.