Lets Talk Gearing....Caution!

5 replies to this topic

Posted November 05, 2001 - 06:53 AM


Found out why I got hurt last week...and to make a long story short it was ALL my fault. A month of so ago I decided that I was tired of stalling in the tight stuff and just adding a flywheel weight wasn't quite doing the trick. So in my infinite wisdom (NOT) I decided to change out the rear sproket (50) for a Renthal (53) and a new chain. Not bad, it resolved the stalling problem.

I have learned to setup for jumps and technical stuff by listing for a specific engine sound (RPM). This works very well for me when I'm busy checking out the competition on the fly and trying to make decisions about the terrain ahead of time. The one factor that I failed to take into consideration at the time of the gearing change was the condition of the front sproket. When I cased the double a week ago which tore my calf muscle, I could not understand why I had come up short. The engine did not give me any indication that I was not up to speed, In fact It sounded very close to the rev limiter (Which I should have taken as a warning). Especially since I was in 4th gear... :)

Yesterday, out of the blue I decided to remove the front sproket cover and inspect the chainwheel. To my surprise (Because of my stupidy) I found that it was completely worn out.....I mean completely...plus ALL of the teeth were bent oppisite of the chain travel.....meaning that for the most part it was acting like a poker card on a bicycle spoke. I broke the number 1 rule of gear maintenance....ALWAYS CHANGE BOTH SPROKETS AT THE SAME TIME.... By not doing so I have put myself out of action for atleast another 2 to 3 weeks (atleast serious riding anyway).

The moral of this story is "Don't take shortcuts with maintenance" It's easy enough to get hurt by the terrain we ride in, It sucks to get hurt when the weather is nice because of carelessness.

Additionally: I picked up two new sprockets this morning, a new 14 and a 13. Anyone out there running a 13/50 13/52 or 13/53 combination out there? I'm thinking that the 13 is going to make 1st gear obsolete, and make 5th gear usable....

Comments welcome....

Bonzai :D

  • Scott_F

Posted November 05, 2001 - 09:46 AM


Yet another reason to remove those stupid plastic mud catchers. Be sure to retain the aluminum case guard though.

  • WR_Jason

Posted November 05, 2001 - 12:48 PM


Hey I had a similar experience and almost tore my foot off my leg doing a hill climb when all the teeth on the counter sprocket snapped at the same time and I got high sided off the bike going backwards down the hill :) . I knew the sprocket was pretty beat but since I had never changed it yet I did NOT know it was alumimum!!!! I did not even know they made such a stupid thing. Needless to say I dont and will never run aluminum sprockets.
I am running 13 52 gearing on my 99 WR 400, Its the best combo for me. Yup, 1 st gear is almost usless except for starting out on steep hills, riding in VERY slow kiddi rides and engine braking, but it makes 2nd gear very usable and eliminates the uncomfy flogging of first gear or constant shifting between 1 and 2. Oh yeah you can use 5th too. I ride alot of tight trails and hills and I can practicly live in 2nd gear unless there is a pretty big straight away or fast jumps. Being on it in 3rd on a hill means getting air at the top :D .

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  • The_Missile

Posted November 05, 2001 - 11:08 PM


Yamakaze....'no comprende'.... :)

If you changed to shorter gearing (which I believe you did) for the same engine noise (RPM) you would be travelling slower and therefore coming up short???

Or are you saying that you were fooled by the additional noise from the chain/cog. But wouldnt that noise/vibration have been different from a high(er) RPM ????

Or have I got my head in my &%ç and missing the obvious ??

Anyway....mend well.

  • MN_Kevin

Posted November 06, 2001 - 01:17 AM


One tooth smaller on the countershaft, and very pleased w/ the results!

I agree, REMOVE THE STUPID SPROCKET GUARD. Rocks can get pulled in and crack that beautiful engine case. Learned this little trick a long time ago.


Posted November 06, 2001 - 02:19 AM


The higher than normal RPM was caused by the chain slipping across the countershaft sproket because the teeth were worn and bent in the direction of the pull to a point where it was not biting as it should have. A couple more hard rides and the sproket would have probably disintergrated or rounded off completely.

Bonzai :)


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