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| Author | Comment | ||
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 boogieman |
Sprocket ratios and how they affect a bike? And what do I need? |
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Posts: 1169 (02/24/08 6:07 PM) |
I have an option of a 48 or 50 tooth rear. I am planning on an offset sprocket from cyclex (front) that come in 16, 17, or 18 tooth.
So I guess my question is what would be a good combination? EDIT: Oh yeah, does a harley sprocket take a 530 chain?
"A Chopper is the final romantic expression that is left in this country. Obviously the frontier is gone. The cycle is the one thing that
you can build from nothing, just a basket, and make into something very beautiful and really put yourself into it." -Cliff Vaughs
Last Edited By: boogieman 02/24/08 6:31 PM.
Edited 1 time.
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Houndog750 |
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Posts: 1300 (02/24/08 6:45 PM) |
I'm not certain on the HD chain, but most likely you're going 530 with that many teeth.
Stock ratio for most is around 2.66 revolutions at counter sprocket to one at rear. The higher the counter sprocket number, the higher the RPMs overall but the more torque at lower speeds. Stock at highway speeds has the RPMs fairly high but off the line it's still pretty wooly. 18/48 is 2.66 to 1, 17/48 is 2.88 which would be damn quick off the line but winding out on the highway. I am running 2.31 to 1 on my bagger which is a little tall but runs smooth on the highway, and my chop is 2.33 to 1 which is a little quicker. Number of rear teeth divided by number of front teeth will give the the ratio. larger number is more torque but higher RPMs, smaller number is less torque but lower RPMs.
It was Honda first, all through the middle, and if I have my way, till the end as well.
Most people say what they'll do. Very few actually do what they say. |
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oldhemi |
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Posts: 1746 (02/24/08 7:25 PM) Senior Member |
Old harleys took the 530 chain. last one I rode was in '76. I think that they are still the same.
HD750 is right in that a little change is certainally noticable on our bikes. I ran 17/45, switched to 18/48 and hated it in the twisties. 2.65 to 2.50 In a cage, you would not notice it at all. The smaller the front sprocket, the more stress on the chain. But today's chains are much better and can handle the smaller sprocket better. 17 tooth and less allows you to run the Honda case protector - if thats what you want to do. I do. What size tire are you going to? And what frame? Here is a sprocket conversion chart: http://www.dropbears.com/u/utilities/sprocket.htm Cant get yuka to cooperate with the link tonite
Last Edited By: oldhemi
02/24/08 7:30 PM.
Edited 4 times.
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jpswino |
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Posts: 409 (02/25/08 6:05 AM) |
Depending on how involved a discussion you want to have on this subject, there are other issues first to consider. Is it a stock motor? Usually, to optimize
performance, matching the cam, intake, exhaust configuration is what is balanced with the rear wheel ratio in conjunction with what has been previously stated
above. Second question then becomes what type of performance i.e. stop light drags (torque most important) or top end speed (horsepower). The gearing you use
will optimize the power output of both torque and HP depending on use of the machine. Good torque is not produced on these motors from idle so a few rpm's
are needed but for the most part torque is produced first and HP builds with rpm. Gearing allows you to be in the "sweet spot" of where your motor
makes power (and the type of power needed) for your application. Keep in mind overall rear tire size matters. The bigger the wheel, the harder to spin, but
probably won't come into play for you build. "Racer's" rant over.
"In the wind, with my mind on my money and my money on my mind"...now I just gotta get some.
Last Edited By: jpswino
02/25/08 6:08 AM.
Edited 1 times.
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ubique2 |
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Posts: 2677 (02/25/08 6:50 AM) G.O.T.F. Member |
I went with an 18/50 combo on one of the bikes that I am building. It is, as I recall, is a 2.77:1 ratio which is comparable to the 2.82:1 that a 17/48 ratio
is. The difference will be minimal on the old SOHC's but would give you decent on the hiways and good off the line. The 18/48 that came stock on many bikes
would have a better top speed but less off the line. I have done as low as 3.2:1 (15/48) and although it sucked for top speed, getting to my top speed was
quick and fun.....
I would run the 17/50 combo from Ken
Maple Leaf Customs
I think I've lost my mind.....again My sandbox etiquette sucks but you all knew that.......and now I am off to the sandbox........ |
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74rat |
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Posts: 4234 (02/25/08 7:31 AM) |
I run the stock 18/48 and am very happy with it..I average/run around 70MPH+ on the highway for fairly long distances..no problems..aint no slacker around the
city either..
74rat when in doubt..knock`um out...H.C.C.M.F LOCAL 6978 Flint Michigan..3rd most dangerous city in the USA..come back and visit us..sorry we "missed" you the first time..LOL |
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boogieman |
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Posts: 1173 (02/25/08 10:59 AM) |
This is for my black chop (look at my profile). It is a custom frame. It is going to have a 2006 HD night train wheel, which takes a 200/55/R17 tire. It's
pretty wide (as wide as I would ever want to go anyways since I'm not a fan of crazy wide tires lol). I am going with an exile sprocket-rotor setup
(sprotor) for clearance issues. I think a regular setup with a rotor on one side and a sprocket on the other would work. Problem is, the wheel took a pully. I
could get an adapter sprocket, but by the time I did that and bought all the stock stuff (man are they proud of that take-off stuff $$$$$$) I would have close
to the same money in it. I think the sprotor setup is cool anyways so why not?
oldhemi, What case protector are you talking about? Is it the little metal part that goes inside the case? I would think that would be good insurance against chain breakage but do the newer chains really have issues? I doubt if I will be doing burnouts/wheelies/stuff like that. I used the 530 chain ken sells on my purple chop and will probably be using it again, it's a good chain. It sounds like an 18/48 or a 17/48 would be the best for me. An 18/48 sounds better but I am wondering about that case protector now.
"A Chopper is the final romantic expression that is left in this country. Obviously the frontier is gone. The cycle is the one thing that
you can build from nothing, just a basket, and make into something very beautiful and really put yourself into it." -Cliff Vaughs
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 Sasquatch |
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Posts: 2603 (02/26/08 9:18 PM) |
I've got a 17/37 combination with a 16" rear tire on mine.Thought it would be a little tall for living in the mountains,but it seems to work
well.It's not shy getting off the line and has plenty of balls on the freeway............
Only Bikers understand why dogs love to stick their heads out the car window................. 
When I die,I want to go quietly in my sleep like my Grandfather......  ...Not screaming and yelling like the passengers in his
car........ 
Last Edited By: Sasquatch
02/26/08 9:25 PM.
Edited 1 times.
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