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Discussion Starter #1
Ok so I'm putting this here because I don't know where to actually post this. So the 500 tops out for me (a 230 lb man) at about 95 mph, but this happens in 5th gear. Since there still seems to be some headroom (6th gear) I was thinking of changing the sprockets to gain some mechanical HP. I know the mpg will take a hit but the $6 a week fill up right now is not keeping me up at night. I wanted to play around with Gearing Commander but I don't have the info needed, eg primary drive ratio, final drive ratio, chain pitch and chain links. Any one have the info? Here's the URL to Gear Commander ( http://www.gearingcommander.com ) what do you guys think a good idea?
 

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Someone has already done this, but not sure if it was a 300 or a 500 thou.
But there is a thread here somewhere.

But in regards of the 6th gear, you won't be able to gain any more speed from it. The bike max out at 105 mph, doesn't matter if you're in the 5th or 6th gear. So the 6th gear is simply a cruising gear to get the mpg down a notch. Nothing else. If you want higher speeds you need higher ccm.
 

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Discussion Starter #4
Ok so mechanically I would hit the Rev limiter in 5th gear at 105. Where do you think I can get the Gearing info for gear Commander from?
 

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And keep in mind I'm not trying to gain top speed. I was just kind of guessing there might some room to raise the oomph without loosing so much top end speed since there is still a sixth gear left.
 

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Since it's the same engine from the CBR bikes, I would start looking there. There will be some difference thou, since Honda re-tweaked the engine when they put it in the 2017 Rebel. So the engine allready has better "oomph" as you call it, than the CBR bikes.
Exactly what Honda did to achieve this I do not know. Could look into that, see if it's possible to gain even more from whatever they did.
Besides this, I do not know. The Rebel ain't meant to win any street races, so can't really see the need for anymore "oomph", but to each their own ofc.
 

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Discussion Starter #7
Yeah I get that. And it's not so much I want to win any street races but if there is a little more in there that can be had without sacrificing too much why not
 

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I geared mine to drop the RPM's on the highway. So overall I lost a bit of off the line and overall acceleration, also mine is the 300. I was able to use cbr300 sprockets. Hopefully the 500 CBR sprockets could interchange as well.
 

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Yeah me too. I'm hoping to do the opposite actually trade a little top speed for some power
You don?t really need to work it out to the end degree. All you need to do is either put on a bigger rear sprocket or a smaller front sprocket. 1 tooth on front is roughly equal to 2.5 teeth on rear. You may have to lengthen the chain if you go with the larger rear sprocket. If you have the ABS model to speedo should stay true. If not, you may need a speedo healer.
 

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I geared mine to drop the RPM's on the highway. So overall I lost a bit of off the line and overall acceleration, also mine is the 300. I was able to use cbr300 sprockets. Hopefully the 500 CBR sprockets could interchange as well.
Would you be able to tell us more about how you would compare the re-gearing?
I'm noticing that my 300 feels "comfortable" up to about 45-50 and above 50 it seems to be working significantly harder and torque seems to drop off.
Did you you re-gear 14 teeth to 15 teeth?
What MPHs are you noticing changes at now?
Is highway riding more comfortable?
 

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Here's a great website that let's you compare sprockets.

https://www.gearingcommander.com/
Cool, super useful site.
Did you use the Honda CBR 300? It looks like they don't have settings for CMX300 yet.

Looks like +1 front tooth will gain less then 10 mph top speed, and only about 4mph where I'm looking for it.

I also learned that I am not pushing my bike hard enough. Without the tachometer I wasn't exactly sure where to shift and would shift when it started to get loud, but now it seems like I'm been shifting too early based on RPM calculated from that site.
 

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Being slightly mechanically impared ... could someone tell me how to calculate the sprocket size change. I hate the fact that the bike feels like it's maxed out at 60mph as well as the tight ratio in low gears (I'll get ankle fatigue just running thru the gears) and so thought of changing the rear sprocket (less futzing with fit even if it means different chain). How do I calculate the impact of changing the sprocket ratio ?
 

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Being slightly mechanically impared ... could someone tell me how to calculate the sprocket size change. I hate the fact that the bike feels like it's maxed out at 60mph as well as the tight ratio in low gears (I'll get ankle fatigue just running thru the gears) and so thought of changing the rear sprocket (less futzing with fit even if it means different chain). How do I calculate the impact of changing the sprocket ratio ?
check out the website https://www.gearingcommander.com/
 

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Changed my front sprocket up one tooth on 500 , much smoother at 60 mpg and easier taking off with smoother take up of drive.
Small downside is the speedo is out by 4 to 5 mph , so watch the speed limit
 

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Being slightly mechanically impared ... could someone tell me how to calculate the sprocket size change. I hate the fact that the bike feels like it's maxed out at 60mph as well as the tight ratio in low gears (I'll get ankle fatigue just running thru the gears) and so thought of changing the rear sprocket (less futzing with fit even if it means different chain). How do I calculate the impact of changing the sprocket ratio ?
I will give you the example for my CB500X that I have not yet needed to install (OEM chain is still OK).

Rear sprocket changes are all that I ever do after the minuscule but significant differences between CRF230F and CRF230L drive sprockets: current 41 teeth; replacement 39 teeth

Change = |41-39| / {(41 + 39) / 2} = 2 /40 = 1/20 = 5% change

This change will lower the engine speed by 5% in top gear.

For my CRF230L I needed much more climbing power, so I went from a 39 to 48 tooth rear sprocket.

Change = |39-48| / {(39 + 48) / 2} = 9 / 43.5 = 0.207 =20.7% increase in engine speed compared to the stock gearing. I no longer have to feather the clutch on steep climbs. :eek:

 

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looking at the gear commander page. seems like a 17-38 gearing wouldn't be that bad. might be slower off the line but better for highway cruising. lower rpms at highway speeds. would a 17 even fit the front on these?
 
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