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+--- Thread: How To :19 tooth front, and now, a 37 tooth rear sprocket on 2013 (/showthread.php?tid=4634)
How To :19 tooth front, and now, a 37 tooth rear sprocket on 2013 - pekingduck - 10-05-2014
I've written about installing the 19 tooth countershaft sprocket on my 2013 model to reduce engine rpms (and vibration) at highway speeds. It dropped the 70mph rpms from 4000 to about 3775, a noticeable improvement, but I wanted more.
The sprocket needed to be steel for it to last at all. The sprocket bolt pattern/inner diameter are common to a lot of big Hondas (VTR1000, '94-'95 CB1000, Blackbird) but none used anything smaller than 39T. I called all the US manufacturers, found one back East, but there were problems, and not all their fault.
I met Jim Alfaro of 7th Gear Design at the Venice Vintage show, saw the quality of his sprockets, and knew this was the answer. I gave him the dimensions and requirements, ordered it and got it in less than 2 weeks. The sprocket had to have lightening slots, and the stud holes had to be counter-bored to clear the nut flanges. It is about 7 ounces lighter than stock and looks just great - I should have bought 2 so I could hang one on the wall!
The last pic shows from left to right, 7th Gear Design, Stock, and less than satisfactory first (and 2nd) ones.
Installation was a breeze. Here's a tip - to loosen or tighten sprocket nuts, do it with the wheel in place. Stand on the right side, put your foot on the rear brake, use a 19mm socket and a 1/2" drive ratchet/breaker bar, and you can break loose the nuts with ease. If you take the wheel off before loosening the nuts, you will be fighting to hold the wheel. Reassemble and torque the nuts in the same way - 80 ft/lbs torque.
Now, 70 mph is about 3600 rpm, roll on torque is still strong, and vibes are noticeably more comfortable. (Yes, you can record accurate rpm/speed on the centerstand).
7th Gear Design also makes countershaft sprockets and aluminum rear sprockets with any type of lightening holes/slots. Price was $75 plus $12 shipping. I cannot say how happy I am with the outcome.
RE: 19 tooth front, and now, a 37 tooth rear sprocket on 2013 - Kai Ju_imp - 10-05-2014
Good info, nice write up and pics. Thanks.
A whole lot cheaper than trading your '13 in on a '14.
RE: 19 tooth front, and now, a 37 tooth rear sprocket on 2013 - Randy B - 10-05-2014
This looks as if it has moved back considerably. Could it be necessary to remove a link from the chain?
(10-05-2014, 02:29 PM)pekingduck_imp Wrote: I've written about installing the 19 tooth countershaft sprocket on my 2013 model to reduce engine rpms (and vibration) at highway speeds. It dropped the 70mph rpms from 4000 to about 3775, a noticeable improvement, but I wanted more.
The sprocket needed to be steel for it to last at all. The sprocket bolt pattern/inner diameter are common to a lot of big Hondas (VTR1000, '94-'95 CB1000, Blackbird) but none used anything smaller than 39T. I called all the US manufacturers, found one back East, but there were problems, and not all their fault.
I met Jim Alfaro of 7th Gear Design at the Venice Vintage show, saw the quality of his sprockets, and knew this was the answer. I gave him the dimensions and requirements, ordered it and got it in less than 2 weeks. The sprocket had to have lightening slots, and the stud holes had to be counter-bored to clear the nut flanges. It is about 7 ounces lighter than stock and looks just great - I should have bought 2 so I could hang one on the wall!
The last pic shows from left to right, 7th Gear Design, Stock, and less than satisfactory first (and 2nd) ones.
Installation was a breeze. Here's a tip - to loosen or tighten sprocket nuts, do it with the wheel in place. Stand on the right side, put your foot on the rear brake, use a 19mm socket and a 1/2" drive ratchet/breaker bar, and you can break loose the nuts with ease. If you take the wheel off before loosening the nuts, you will be fighting to hold the wheel. Reassemble and torque the nuts in the same way - 80 ft/lbs torque.
Now, 70 mph is about 3600 rpm, roll on torque is still strong, and vibes are noticeably more comfortable. (Yes, you can record accurate rpm/speed on the centerstand).
7th Gear Design also makes countershaft sprockets and aluminum rear sprockets with any type of lightening holes/slots. Price was $75 plus $12 shipping. I cannot say how happy I am with the outcome.
RE: 19 tooth front, and now, a 37 tooth rear sprocket on 2013 - pekingduck - 10-05-2014
Thanks for embiggening the pics.
I'm not too worried about chain wear as I am generally easy on chains. My 1980 CBX had its chain adjusted only about 5 times in 20k miles, and my previous WeeStrom's chain was still going strong when I sold it at 48k miles.
New chains are so much more durable now that they have lube sealed inside. Also helps to not grab a big handful at low rpms, get it spinning up first.
Adding a tooth in front and reducing 2 in the back had the least impact on the wear indicator - they almost negate each other.
I'll take a picture of a new bike to compare starting adjustment.
RE: 19 tooth front, and now, a 37 tooth rear sprocket on 2013 - CIP57_imp - 10-05-2014
Thanks for doing the footwork and the rear sprocket looks great. So, 1 extra in front minus 2 in rear, I'm wondering how much it has changed the line of travel on the chain slider?? There are wear indicators on the slider and would be a good idea to keep an eye on that in the next 1000 miles.
RE: 19 tooth front, and now, a 37 tooth rear sprocket on 2013 - Kai Ju_imp - 10-05-2014
I don't think the slider would be affected all that much since the reduction in diameter is at the rear wheel while the C/S sprocket went up in size, which should reduce slider wear.
It would be interesting though to see if there is any effect on handling in regards to the torque effect on the swingarm.
That custom sprocket looks so much nicer than either the stock or your first try at a smaller sprocket.
RE: 19 tooth front, and now, a 37 tooth rear sprocket on 2013 - CIP57_imp - 10-05-2014
(10-05-2014, 11:38 PM)Kai Ju_imp Wrote: I don't think the slider would be affected all that much since the reduction in diameter is at the rear wheel while the C/S sprocket went up in size, which should reduce slider wear.You may be right since the chain hits the slider in the front and you have at least a quarter inch clearance in the back on a stock set up
It would be interesting though to see if there is any effect on handling in regards to the torque effect on the swingarm.
That custom sprocket looks so much nicer than either the stock or your first try at a smaller sprocket.
RE: 19 tooth front, and now, a 37 tooth rear sprocket on 2013 - CB4ME_imp - 10-05-2014
I did +1 in front and -1 in rear. But the rear sprocket is gold anodized aluminum. So far no signs of wear but I'll keep an eye on it.
![[Image: 33a8a9c66168e8a9cc28cafb2d634e12.jpg]](https://cb1100forum.net/forum/uploads/imp/201410/33a8a9c66168e8a9cc28cafb2d634e12.jpg)
I really like the mod. Thanks for posting the original thread and this one.
RE: 19 tooth front, and now, a 37 tooth rear sprocket on 2013 - redbirds_imp - 10-07-2014
I'm interested in doing this mod when the original sprockets are worn but what about speedometer accuracy. I went to a larger counter shaft sprocket on my Triumph Tiger 1050 to reduce rpm's at cruise speed. This mod had the added benefit of making the speedometer dead on where as before it had been a bit optimistic. The CB1100's speedometer is quite accurate with stock gearing. Does the change in gearing have an effect on the speedometer's reading? If the speed sensor is located at the front wheel there's no problem but most bikes have the sensor located to measure speed at the counter shaft sprocket.
RE: 19 tooth front, and now, a 37 tooth rear sprocket on 2013 - Pauley - 10-07-2014
The speed sensor is on the back wheel (front wheel sensor is for ABS if so equipped). Changing the drive sprockets won't effect the speedometer. If you switch tires to something with a different width/aspect ratio (tire with a circumference that's different from the stock 140/70-18's) - that will effect the speedometer calibration.