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Question on gearing up, sprocket change

14K views 27 replies 16 participants last post by  Sal Paradise 
#1 ·
I have a mechanically stock '07 Bonneville. I need feedback from anyone here who has done this. I would like to change sprocket to gear the bike up for lower rpm at highway speed. How did you like this change and how did it effect the rest of the gears? Is this a definite thing you recommend or were there some cons to this. Thanks for any feedback.
 
#2 ·
I've done it on my 05 Speedmaster. Put a 19T front on in place of the stock 17T. Lowered overall revs by about 400-500. Does require a little more revs and clutch slip to get going but not noticeable after a few times doing it. My bike does breathe a lot freer than stock and I found i needed to fit Barnett green springs as was getting a little clutch slip when cold under acceleration. I highly recommend it. Some say you lose low down drive when going through the tighter corners but really all you need to do is drop down another gear.
 
#4 ·
Going up on the front lowers the gearing, as does going down on the rear. I've seen a 19 front with a 39 rear on a 2001 before - heavily overdriven, lots of clutch slipping to get it going, but a nearly 1000RPM drop in 5th gear. That should do wonders for engine life.

I have used a 19 front with the stock rear and liked it a lot on long, less interesting rides. Just that much less buzziness. I missed shorter gearing during more interesting rides. Just that much less ooompf.
 
#5 · (Edited)
Like rweb, I had a 130/80 rear matched with the 19T front sprocket. It was no dragster off the line but she cruises along beautifully with plenty of top end speed to be Illegal if required. :D
On a side note, I did have my CDI breathed on by Pieman many years ago, he upped the Rev limiter to 8200rpm for me which enhances the other two changes as mentioned above for my 04 Bonnie.

Penske, I'm bias but I say "Do it!" :D
 
#6 ·
I fitted the 19T sprocket to get that more relaxed feeling, and it works for me. I haven't noticed the problems of too high a gear for town, but I guess it must have some effect.

There are other benefits : -

Your speedometer will be accurate
You will (probably) improve your mpg, but that is difficult to quantify, as your readings have changed.
Your engine is less stressed (but maybe your clutch works a bit harder ? )

Like I say, it suits me.
 
#8 ·
Running 19 tooth and a 140 80 rear which further raises the gearing. My bikes running the TTP high torque setup with Breathe, Airbox baffle removed an tracker 2-1 exhaust. The bike is a real tractor and pulls well from idle. Don't see many hills in my area so the 19 tooth works well, but on my occasional trips to the mountains the difference is noticeable. Gear selection is more critical with the higher gearing with some tight uphill hairpins requiring 1st gear.

It really depends where and how you ride, cruising the flat areas high gearing is fine and helps a little with fuel consumption. The stock gearing works well over a variety of situations and is better for the twisties or around town.


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#12 ·
Back to stock

I had a 2007 Bonneville for a couple of years until I got my current bike. Never changed the sprocket. I did however change from the 18T to 19T on the Mag bike. I did not realize just how it had taken the zip out of the bike. So, Monday night back to stock sprocket. As usual, I don't know what the engineers know. My advice is stay stock.
 
#14 ·
@bobscogin No bad side effects other than a slight feeling of a small loss of zip as can be expected. After mounting it I went to the N. Ga. mountains and it was great, probably because it was new more than changing rake from the slight height difference. This is on my T100, it is now worn out and I have a new one on order. I would recommend it for all around riding. On my Thruxton I stayed with the original size.
 
#23 ·
Last year I went up one tooth on the front sprocket to slow the engine a bit on the highway. After about a week, the change was forgotten. The engine is just a bit less frantic on the highway and when the bike needs new sprockets, I will go further with this; down one tooth on the rear sprocket. It's not much of a change; just a tendency in the right direction for my liking.

I did similarly with my Sportster, up one tooth on the front and later down one on the rear, and it makes the bike a more calm highway cruiser. Some accept frantic to get max. acceleration and that's ok but I am moving more to calmness. It's a personal choice and if you don't like it, you can easily go back to stock.

Gas mileage goes up but not much.
 
#25 ·
Going back to 18 tooth.


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I just did this. And I really wish I had asked this question first. Its a mixed bag. My T100 is stock, and I found the bike drags a bit coming out of a corner. OTOH, it gets a bit better range per tank and it really does seem like the revs are lower and the whole ride is smoother. So I like that. Its nice for just cruising.

But, personally I like carving the curves and accelerating out of turns. Now, when I'm exiting the turn and I roll on the throttle the bike is in no rush. I'm surprised it makes so much difference.

I will be going back to the 18 tooth front sprocket soon.
 
#26 ·
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I just did this. And I really wish I had asked this question first. Its a mixed bag. My T100 is stock, and I found the bike drags a bit coming out of a corner. OTOH, it gets a bit better range per tank and it really does seem like the revs are lower and the whole ride is smoother. So I like that. Its nice for just cruising.

But, personally I like carving the curves and accelerating out of turns. Now, when I'm exiting the turn and I roll on the throttle the bike is in no rush. I'm surprised it makes so much difference.

I will be going back to the 18 tooth front sprocket soon.
You can always just change down a gear and you have best of both worlds.
 
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