Gearing? confused

7 replies to this topic
  • RMK800

Posted March 09, 2014 - 10:06 AM


Yesterday me and my son got out for a great ride. I just got him an 06 250x. What I really like about his bike was the gearing, especially the engine braking on steep down hills. We do a lot of that where we ride.

The stock gearing for this 250x is 14/53. This is where I'm confused. My 07 wr450 is 13/50. It's not even close when coming down a steep hill. I use a lot more brakes on my WR then that Honda. Going by those number the WR should have more engine breaking. They are obviously two different bikes and maybe that's the reason.

Another question I have is I want to go to a 52T in my rear. I think this would be ideal for what I ride. Can I use the stock chain? I heard if it does fit you have a shorter
wheelbase and it a wheely machine. Maybe a new chain and sprocket Is required.

  • Krannie McKranface

Posted March 09, 2014 - 10:56 AM


The WR has less engine braking than a CRF. I own both.

....but all you have to do is down shift....


...and the stock gearing on the CRF is 13/54

  • RMK800

Posted March 09, 2014 - 11:27 AM


Are you sure on the 250x. Ramsey and this website show


Downshifting is fine, but when you got more terrain ahead and it doesn't allow you to go fast. Then you use your breaks. I also find if it's loose dirt, engine breaking is easier then running the breaks. I can ride the stuff I ride, but trying to make things easier for me. I don't need as much top end 60mph is plenty for what I ride.

  • Krannie McKranface

Posted March 09, 2014 - 01:11 PM


You are right, I mixed it up with the 450X


Internal transmission gearing and net final drive ratios are the only thing that matter


14/54 and 13/51      : 13/51 is geared lower, so you have less engine braking in the same gear, assuming the internal ratio is exactly the same.

Edited by TheKoolAidMadeMeSick, March 09, 2014 - 01:16 PM.

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  • flyandride

Posted March 09, 2014 - 06:49 PM


Another good site for gearing related questions and calculations is

  • RMK800

Posted March 10, 2014 - 08:15 AM


Ya, I saw that site also.    It goes to show you, you can't compare two bikes with gearing.  I have confirmed both bikes have stock gearing.


The 250x with a 14/53 - gear ratio 3.78


The WR450 with a 13/50 - gear ratio 3.84


By the numbers you would think that the WR450 would have more engine breaking.  In my testing and I did this many times on the same steep hill with both bikes. The WR had less engine breaking then the 250x.

Edited by RMK800, March 10, 2014 - 09:28 AM.

  • grayracer513

Posted March 10, 2014 - 10:19 AM


You haven't figured out what the actual overall gear ratio is, in the first place.  The primary reduction ratio, the gearing between the engine and clutch, is going to be considerably different, for one thing.  Then there's the question of what the transmission ratios are in the gears being compared.  You're comparing final drive ratios as if that were it, but the 3.846:1 ratio the chainset produces is only a part of the equation.  In second gear, you're working with a 1.733:1 ratio, and your primary gearing is 2.652:1.  Your true overall gearing is primary x trans x final, or 2.652 x 1.733 x 3.846, which comes out 17.676:1.  What's the overall ratio on the X?


Then you have vehicle weight.  The presumably heavier WR will not be slowed as much by the same amount of resistance as will the lighter X even if all factors of either are equal.  Other things related to internal engine design influence the amount of engine braking you have, too, such as rod angle, wrist pin offset, stuff like that.  You're not comparing like-to-like at all.

  • RMK800

Posted March 10, 2014 - 01:45 PM


Good point not a good comparison. This gearing is new to me and you make a great point about bike weight, that is most likely the difference as well as your other points.   I obviously have lots more to learn besides comparing sprocket sizes. Thank you for your feedback Grey and everybody's feedback.

This brings up a funny reminder. You read and read, all these things have numbers from gearing to HP. But as I have read from others... My seat of the pants testing tells me this :ride:

Edited by RMK800, March 10, 2014 - 03:46 PM.


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