I really like the style of sprockets that Bonneville Performance uses on their custom street and super tracker bikes. They features round holes which I think would look good on my Bonneville, what with all the hole drilling I have done! So, I asked my friend Bill Gately where he gets those sprockets. He told me that he has them made by Rebel Gears, out of Tennessee.
I contacted Rebel Gears and explained what I was looking for… a rear sprocket design for a stock 525 chain in 41 and 42 tooth sizes. Sandy sent me a template of a design that would work on my Bonneville with a stock rear bolt pattern. They also told me they could only supply the sprocket in 7075 series aluminum for a price of $62.48 each, plus shipping.
Bonneville Performance style rear sprockets and the style recommended to me by Rebel Gears.
I decided to move forward with this order, and received the new sprockets about a week later.
New aluminum Rebel Gear and the steel gear I am replacing.
Last night I mounted the new sprocket on my rear wheel.
New aluminum Rebel Gear mounted on rear wheel hub.
I decided to start with the 41 tooth gear since I am already using a 42 tooth steel gear. I want to find out how much it affects high end cruising speeds and lower RPM for better fuel economy. Because of the one tooth difference, I also needed to adjust my chain tension by moving the entire wheel and axle back about 1/4.” This is easy to do with the Triumph Bonneville chain tension adjusters that come stock on the bike.
Finished shot of mounted rear wheel with new Rebel Sprocket.
The stock chain tension adjusters seen in the photo above use an 8mm hex head that is easy to adjust with a ratchet wrench.
Another view of new Rebel Gear.
I am very pleased with the initial quality and look of these gears. I noticed that the thickness of the gear matched the inside thickness of the chain much better than the former steel sprocket. It’s a much better fit.
Update May 19, 2014
This weekend I was able to put some miles on the Bonnie with the new rear sprocket set up. I really like the improvements in several ways:
- The new look is awesome!
- The slightly lower gear ratio lowers my RPM’s at cruising speeds making long rides more comfortable.
- The ratio is also still high enough that I do not notice any serious loss of “off the line” power… something I am not that concerned about anyway.
- The snug left to right fit of the chain on the sprocket seems to be quieter… maybe it’s also related to being aluminum.
I’m very pleased with the results, I may even order a 40-tooth and try that as well.
Aluminum? I’m confused. Wouldn’t steel be a better choice? (You just saw how aluminum affected my life…)
Or, is the application different, here?
Lee, apparently this type of aluminum is strong enough for this application. Bill uses it on his Bonneville Performance super trackers! Time will tell! – Randy
Are you still running the 19-Tooth Front Sprocket as well?
Kevin,
Initially I was still running the 19-tooth front. However, I recently switched back to the stock 18-tooth to test this setup out for potential track day use. For highway cruising (like for my upcoming Tail of the Dragon Road Trip), I like the 19-tooth front, 41-tooth back setup. For track days I will switch to an 18-tooth front and 42 or 43 tooth rear setup for added torque in cornering. That’s my plan at this point.
Hope that helps…
Randy
with the 19 front and 41 rear what is your rpm drop in top gear at 70 mph and will it pull this gearing without killing the engine
Dennis,
Thanks for the question/comment. With this gearing setup I am experiencing 3500 to 3700 RPM at 70 MPH… this depends somewhat on wind and road conditions. At 4000 RPM I am right around 75 MPH, and at 4500 RPM I am at around 80 MPH. My Bonnie has no problems getting off the line with this setup as well. It’s not quite as quick off the line as an 18 tooth would be, but it is acceptable to me and a fair trade-off for the lower top end RPM’s. I am even considering getting a 40 tooth rear sprocket.
Hope that helps you make your decision.
Randy
Randy my name is Dave from Washington St.. I read your comment on july 20 2014 about your gear setup with a 19 front and 41 rear. I was wondering if you ever went to a 40 tooth rear and if so did you like it ?
Dave,
Thanks for your question/comment. I never did go to the 40 tooth as I was happy with the performance with the 19 / 41 combination. However, now that I am having my engine rebuilt and bumped from 865cc up to 1100cc, (see http://triumphbonneville.org/taking-a-triumph-bonneville-865cc-engine-to-1100cc/) with an increase to 94HP and 76 ft. lbs. of torque, I may need to drop it to 40 tooth rear just for gas mileage considerations. The rebuilt engine will require premium gas because of the higher compression.
I’ll post here again if I make this change.
Randy