| permachief |
06-15-2014 07:07 AM |
Quote:
Originally Posted by DC.chief
(Post 10688680)
So I picked an 03 shadow spirit 750 as my first bike not even 2 months ago. I've got fairly comfortable riding it and have started commuting back and forth to work on it which is a good 45 minutes to an hour long drive each way.
Here's my issue.. I hit fifth gear by like 45-50 mph. I could ride 4th out a tad more if I wanted but the bike doesn't like it. The pace of traffic here is 70-80. At 70 mph the engine is screaming at me.
I've read up on replacing the rear sprocket with one that has 3-4 less teeth. or just going down 1 tooth on the front sprocket. This should make the bike a tad slower on accel but give it more top end. Many shadow spirit 750 owners say it makes a huge difference.
My question is do any of you have any experience with making that change on a 750 shadow or any bike for that matter. Any tips or advice would be appreciated as I'm new to this. Or is this pointless to waste time and money on and should I just be looking to getting a bigger bike sooner than expected?
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I don't have gearing change experience with bigger bikes like yours but have done gearing changes on smaller (250cc) dirt and dualsport bikes.
If you want to gear the bike higher you would put a smaller sprocket on the rear and/or a larger sprocket on the front.
A 1 tooth change on the front typically is equal to about a 3 tooth change on the rear sprocket.
You calculate the final drive ratio by dividing the rear number by the front number (i.e., 43/14=3.07, 43/15=2.86, 40/14=2.85, etc.) The lower the result, the higher the gearing (I know, its sounds backwards).
The percentage change in the final drive ratio will have the same percentage effect on rpm/mph ratio. For example, changing the final drive ratio from 3.07 to 2.86 is gearing the bike 7.34% higher (3.07/2.86=1.073426). Therefore, assuming that 5,500 rpm in 5th gear previously produced 65 mph, the new gearing will now produce approximately 70 mph in 5th gear at 5,500 rpm (65x1.0734=69.77). (Note: This also assumes that the engine has the needed torque to actually pull the higher gearing which may not always be the case especially in smaller cc bikes.)
With the bikes I have experience on, you can typically change the front sprocket +/- one tooth without lengthening or shortening the chain. A change of +/- three teeth on the rear may require a chain length adjustment (it just depends on how much adjustment span is available on the swing arm where the rear wheel is mounted.) So typically, the front sprocket is the preferred sprocket for a gearing change initially (and front sprockets are typically cheaper than rear sprockets).
Getting your bike properly geared for your specific use is definitely worth it. It will only increase your enjoyment of the bike. |
