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RADBMX.CO.UK  |  Technical & Reference Section  |  Tech and Restoration  |  chainwheels
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Author Topic: chainwheels  (Read 791 times)

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fritz78

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chainwheels
« on: February 11, 2008, 06:58 PM »
should i get a 43 tooth chainwheel or a 44 tooth one? does it matter? i have 17t freewheel if that makes any difference

Offline meticulous

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Re: chainwheels
« Reply #1 on: February 11, 2008, 07:10 PM »
i would say 44t at front, as a rule 44t front and 16t rear was always a good combo, it depends on how fast you  want to go or how fast you want to pedal, bigger the cog on the back the faster you pedal, the smaller the cog on the front the faster you pedal,thew!!! got that! go for 45 if you can at front, that would give you the same gearing as 44x16 :daumenhoch:
R.I.P  O.M. Far short of the finish line...

eloopnai

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Re: chainwheels
« Reply #2 on: February 11, 2008, 10:25 PM »
was gonna post a question about gearing myself so will ask it here now
ive got a 46 chainwheel so does that mean 18 freewheel ??
cheers lads

Offline Brandy Truffle

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Re: chainwheels
« Reply #3 on: February 11, 2008, 10:33 PM »
Hmmm, i got an old mag somewhere which gave a complete explanation of the gearing for BMX'ing and consequences of running bigger/smaller/front/back gearing and all the combos in between. Will dig it out,as thats one thing that foxes alot of people still...

I ran 44t/16 racing back in 83..but to be honest,only because thats what i read in most of the magazines top riders were using. Looking at what i know now,i'm sure if i'd have ran a 43,i could have got a few more Holeshots on some tracks  ;D

Will see if i can locate that mag.May make some interesting reading. After all in 25 years,the bikes and technology may have changed quite a bit... but the science and physics of gearing haven't.

Although the 'micro gearing' concept alot of freestylers subscribe too these days i'd like to understand too. I'm sure there are topics here already surrounding gearing,best do a search and see before Mods kick arses,eh?  ;D
« Last Edit: February 11, 2008, 10:37 PM by Brandy Truffle »

SaMAlex

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Re: chainwheels
« Reply #4 on: February 11, 2008, 10:45 PM »
got that! go for 45 if you can at front, that would give you the same gearing as 44x16 :daumenhoch:

44:16 is not the same as 45:17

roughly speeking, you need to go up 3 teeth on the front for every 1 on the rear. The real way to work it out is if you divide the chainring teeth by the freewheel teeth. like this:

44 / 16 =  2.75
45 / 17 =  2.65
47 / 17 =  2.76

44:16 is almost the same as 47:17

You can then take this number and multiply it by the circumference of the tyre you are running to give you your gearing as the distance that one pedal will take you. (not just by 20" or 24"!)

This also shows that one tooth on the back makes quite a big change to the gearing, where as one tooth on the front makes very little.
« Last Edit: February 11, 2008, 11:01 PM by S&MAlex »

lodge

  • Guest
Re: chainwheels
« Reply #5 on: February 11, 2008, 11:00 PM »
Hmmm, i got an old mag somewhere which gave a complete explanation of the gearing for BMX'ing and consequences of running bigger/smaller/front/back gearing and all the combos in between. Will dig it out,as thats one thing that foxes alot of people still...

I ran 44t/16 racing back in 83..but to be honest,only because thats what i read in most of the magazines top riders were using. Looking at what i know now,i'm sure if i'd have ran a 43,i could have got a few more Holeshots on some tracks  ;D

Will see if i can locate that mag.May make some interesting reading. After all in 25 years,the bikes and technology may have changed quite a bit... but the science and physics of gearing haven't.

Although the 'micro gearing' concept alot of freestylers subscribe too these days i'd like to understand too. I'm sure there are topics here already surrounding gearing,best do a search and see before Mods kick arses,eh?  ;D



Its funny when you watch old skool vids that so many people were obviously running the wrong gearing for there riding.



motomagII

  • Guest
Re: chainwheels
« Reply #6 on: February 12, 2008, 10:33 AM »
ive just put 3 bikes together and used what i had gearing wise and they are def odd
ones 39x13 the other is 41 x14

before i chaged the wheels round etc i was running 33 by 13 on me park bike and was quite happy with it .39x13 will be interesting at bradford on saturday


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