Think its time for a new sprocket?

M

madmike90

Member

Aug 3, 2007

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• Aug 7, 2007

• #1

this is my front sprocket off my cr125

http://www.putfile.com/pic.php?img=6236838
http://www.putfile.com/pic.php?img=6236837

im pretty sure its time for a new sprocket, this is a 12 tooth and the rear sprocket is a 52 tooth, is this the best gearing for a bike that will mostly see jumps?

i bought a new front sprocket. also, does this look like normal wear for a front sprocket, or does it look like there is a problem with alignment?

thanks,
mike

 

M

Mr.Selfdestruct

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Jul 28, 2007

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• Aug 7, 2007

• #2

Wow, it looks like a chinese throwing star.

 

M

madmike90

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Aug 3, 2007

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• Aug 7, 2007

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• #3

thats EXACTLY what i said to my dad lol

 

J

_JOE_

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• Aug 7, 2007

• #4

Are you serious? "is it time for a new sprocket?" :think:

 

M

MXer666

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Jul 15, 2007

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• Aug 7, 2007

• #5

thats not that bad at all, ive had worse :P

 

M

madmike90

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• Aug 7, 2007

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• #6

_JOE_ said:

Are you serious? "is it time for a new sprocket?" :think:

Click to expand...

:) i was being sarchastic haha.
my main point of the thread was to ask if 12-52 is good gearing for a jump bike.

 

Someone

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Mar 12, 2001

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• Aug 7, 2007

• #7

We call that "Ocean Spray".

125cc 2 smoke a "jump bike"?

 

F

FistFullofDirt

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Jul 15, 2007

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• Aug 7, 2007

• #8

Not bad at all? thats horrible, worse than bad. How did your chain last?

 

IndyMX

Crash Test Dummy

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• Aug 7, 2007

• #9

I'd run 13 but that's just me

 

M

madmike90

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• Aug 7, 2007

• Thread starter
• #10

im looking for the best gearing for jumps and wheelies, i have 2 other bikes and this one will be wheelie/jumps only. the others i bought set up already, 1 for trail riding, 1 a bit meaner for the track.

thanks in advance

mike

 

Jaybird

Apprentice Goon

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• Aug 8, 2007

• #11

The chain being worn out is what ruined the sprocket. If the rear doesn't look like that, it is either a super hard *steel rear, or will look like the front very soon.
*(even a super hard rear will be worn like the front if you continue to run the same chain.)
If the rear has even the slightest bit of deformation at all, change it too.

12/52 gearing is more suited for woods riding in sigle track.
For the track, a 13/49-52 would be a better ratio choice for the 125cc.

 

RM_guy

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Damn Yankees

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• Aug 8, 2007

• #12

Naw...that sprocket's fine. Now this one's bad! :laugh: :p

 

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• sprocket.jpg

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J

_JOE_

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May 10, 2007

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• Aug 8, 2007

• #13

RM_guy said:

Naw...that sprocket's fine. Now this one's bad! :laugh: :p

Click to expand...

Wow, a six tooth! Sweeet.

 

W

wake_rider

Member

Feb 21, 2007

481

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• Aug 8, 2007

• #14

I'd just keep it stock ratios and since you are replacing the front sprocket, replace the rear and the chain at the same time. Make sure you scrub your chain well after every ride, and immediately lube it afterwards to keep it from rusting. It will last a long time if you take care of it...

 

M

madmike90

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Aug 3, 2007

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• Aug 8, 2007

• Thread starter
• #15

Jaybird said:

12/52 gearing is more suited for woods riding in sigle track.
For the track, a 13/49-52 would be a better ratio choice for the 125cc.

Click to expand...

what makes the 13/49-52 gearing better than 12/52 gearing?
whats the difference and how does each apply to each application, sorry for all the questions, im just trying to get the best performance possible for what i need out of my bike.

thanks

mike

 

M

madmike90

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• Aug 8, 2007

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• #16

bump

 

BSWIFT

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• Aug 9, 2007

• #17

madmike90 said:

what makes the 13/49-52 gearing better than 12/52 gearing?
whats the difference and how does each apply to each application, sorry for all the questions, im just trying to get the best performance possible for what i need out of my bike.

thanks

mike

Click to expand...

Your 12/52 works out to a 4.33:1 ratio which is very low gearing. The 13/49 works out to a ratio of 3.76:1 and the 13/52 is 4.0:1. The larger the ratio the lower your overall gearing will be. You'll get quick accelleration but your engine will peak very fast resulting in slower overall speed for each gear. The 4.33 ratio is getting close to a trials bike gearing.
I was running just under a 4:1 ratio at one track earlier in the year but was setup for woods. I got a great start but was left in the dust after two turns and I was running WFO. I've since change to a 3.69:1 gearing. I still get outrun by 450's but at least I'm not getting blown away.

 

Last edited: Aug 9, 2007

M

Mr.Selfdestruct

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Jul 28, 2007

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• Aug 9, 2007

• #18

This is good info, im running a 13/49 on my bike, and i was wondering what my gear ration was .

 

Jaybird

Apprentice Goon

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• Aug 9, 2007

• #19

Divide the first number into the second number and you have your gearing ratio.

49 divided by 13 = 3.77
so, your gearing ratio is 3.77:1 or 3.77 turns of the small sprocket for every 1 turn of the rear sprocket.

 

K

Kwakasaki

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Aug 22, 2004

167

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• Aug 11, 2007

• #20

Jaybird said:

The chain being worn out is what ruined the sprocket. If the rear doesn't look like that, it is either a super hard *steel rear, or will look like the front very soon.
*(even a super hard rear will be worn like the front if you continue to run the same chain.)
If the rear has even the slightest bit of deformation at all, change it too.

12/52 gearing is more suited for woods riding in sigle track.
For the track, a 13/49-52 would be a better ratio choice for the 125cc.

Click to expand...

I agree with the chain being worn, done it myself and ruined a new sprocket quickly. Chain may "look" good but dont chance it. :coocoo: