Bonneville America Forums Forums Technical Forums Performance Mods Front sprocket options: 17? 18? 19?

Never been much of a mech I'm afraid so this question is likely to be elementary to most of you. The product description at NewBonneville.com says something like changing the number of teeth on the front sprocket will "help resist the urge to look for that elusive 6th gear on the highway". I have a 17 tooth bumped up from stock 16. If I want to get rid of that "inclination" to search for the 6th gear do I want to go up to 18 or 19 or drop back down to a 16 or 15 tooth? The whole ratios discussion is lost on me. Appreciate the help.

18 or 19 will be what you're looking for, but you'll notice a decline in acceleration

My Speedmaster came with a 16 tooth. I changed it to a 17 tooth after had modified the engine some to get more power. There was slight difference. That changes the ratio only slightly. I think it was maybe only a couple of 100 less rpm at 70 mph. I changed it back to the 16.

I just installed a 17T front on my 07SM stock head/piston 865. The OEM front sprocket was 18T. So far, I am very pleased with the 17T JT sprocket. It just seems natural. Yeah, it revs a bit more at highway speed, but so what, it performs really well.

I would have done this sooner but a series of very serious health issues have basically precluded any normal type of riding since 2016. Man, it sure is great to be back on the bike again.

I still run the 16 tooth front, tried a couple others but like the 16.If I get on it I shift into 5th at about 90MPH why would I want to give up the bottom end tq? I regularly cruise the highway at 80 mph + or -. I ride across several states at times and am happy with it. I can be in Orlando in about 21hrs from NE PA. I have done that several times, Wendys sister lives there. I have never seen any reason to change and can't understand why anyone would want to, with the 16 I can hit 120mph with throttle left. These are all indicated speeds on the speedo with the stock size tires.

Hi Tad !!! Long time no hear from. Hope your doing well.

I run a 19 tooth on mine and love it. Ride it like a 4 speed with overdrive.

I have done some extensive mods for performance so I do not have much lag off the line.

18 tooth would be a better gear for a stock engine.

19 was always my choice. Gears are twice as tall, no trouble two up riding and cruising in 5th was a joy at 75MPH.

After ten years of ownership I finally decided to give a 19 a go.. the bike runs out of puff a little earlier than before in top gear but still quick enough to easily get my licence taken of me, but can hit its all time best top speed in fourth. At the speeds I normally sit on ( 110 - 130 kph or 60 - 80mph ) the loafy feel of the bike makes for a chill out cruise, just what I want in todays hustle and bustle, maybe not the best gearing depending on how you want to ride but it suits me at the moment...

Thanks guys...gonna order the 18 and see. Don't really want to lose a lot of acceleration light to light but I'd like to see what my experience is, specially on the highway where my rpms are screaming in my ear. I'm at just over 4000 RPM's at 70mph which is the sweet spot for my current gearing to shift.

I rode a 19t all over the mountains between Prescott and Grand Canyon twice, never had a problem. I think I kept up with everybody when I was there. You just drive a gear lower than the other people.

Well..I went for the 18...small steps. However, he's up on the lift right now looking like he's in open heart surgery. Cannot remember how the hell I broke out that sprocket nut.

Loving the 18 tooth. Lose a little oomph at a red light but fine after. And the thruway is a gas. Bike sounds just right

You can change your ratio by close to a half value of the front by going up or down a tooth on your rear sprocket.