Rear Sprocket
- Thread starter Big Fred
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canyncarvr
~SPONSOR~
- Oct 14, 1999
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Are you looking for a number?
How about....6? ;)
It's enough of a difference that you'll most definitely notice it.
A 50T rear is a bit tight on the oem chain guide, if it fits at all.
If it's just a question of wondering what will happen, a 12T on the front is much cheaper, easier to change and has no bearing on the guide. Gets you about the same ratio.
......a favorite rant of mine. It takes a couple minutes to change the CSS.
IF your changing the rear to another gear cuz the sprocket is worn out (so why not try a different size?), you probably have more problems than just the rear sprocket.
How about....6? ;)
It's enough of a difference that you'll most definitely notice it.
A 50T rear is a bit tight on the oem chain guide, if it fits at all.
If it's just a question of wondering what will happen, a 12T on the front is much cheaper, easier to change and has no bearing on the guide. Gets you about the same ratio.
......a favorite rant of mine. It takes a couple minutes to change the CSS.
IF your changing the rear to another gear cuz the sprocket is worn out (so why not try a different size?), you probably have more problems than just the rear sprocket.
A 12 is hard on the chain, thus hard on both sprockets...
Which is cheaper, a chain guide or a chain and sprocket set??
Which is cheaper, a chain guide or a chain and sprocket set??
12 is fine for the front. Maybe at speeds faster than the KDX is capable of, there would be problems, but not here. My 1999 KDX220 has it's stock chain and a 12 since new, and it has almost zero wear and stretch. I'm hanging onto my 13 for the day I finally make it to the desert and some high speed stuff.
I guess they went up a tooth in the rear, it was 47 tooth for the longest time.
For my .02 worth, I would suggest leaving the gearing alone and put your money into engine mods or just the regular mods. That will give you all the torque you can handle. No kidding there.
Speed has little to do with it. It's torque and chain pull that works on the chain.
And, if you have a stock chain on a '99 I don't care what CS sprocket you have...you are not riding your bike. Zero wear and stretch? I'd be willing to bet money you have never properly measured your chain.
And if CC chooses to answer the question posed him, no matter what the answer is...it would have been longer if a larger CS sprocket was used.
Jaybird, I don't take kindly to being told I am a liar. I said almost zero wear. KDX220R comes stock with an o-ring chain. The bike is ridden, ridden hard and the chain never needs any maintenance. If it stretched then I would know from the adjuster on the rear. Speed has somethingto do with it. As the chain rollers move from wrapping around a sprocket, wear takes place and the friction will warm it up. If the movement occurs rapidly, friction starts to build and heat will cause problems. Once a chain goes through it's initial stretch, it will usually stop. The only thing I can think of, is that you bought a cheap chain. I wash my chain with a pressure washer and I let it drip dry without any other thing done to it.
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I really wouldn't worry too much about it ski...some people like to nit pick every little thing you say or do and to me at least gaging your wear by the snail adjusters is plenty fine. It's not like the bike was designed by NASA and made to run within a 1/10000th of an inch. I mean, honestly...it's not like your gonna FUBAR your bike or chain by running a 12 tooth sprocket on the front. If that were the case they wouldn't even make the darn things.
skipro3,
First, I didn't call you a liar. But as you provide more information it is obviously clear you have less than a clue about chain maintenance. And even less of a clue about me. I've probably owned more bikes than you can count.
Yes, it's ok....you can use your toes too, we won't call that cheating.
My point is that a 12 tooth sprocket is harder on chains than larger sizes. Some bike MFG's did go to a 12t CS sprocket on their stock offerings but their engineering staff realised it was a bad move and got away from that.
No, it's not going to FUBAR your fubsy bike. (what ever the hell FUBAR is...them fancy words really kinda stump me sometimes) It only will decrease the life of your chain and sprockets as opposed to running a higher tooth front. Usually dealing with mechanical issues there is math that can prove or disprove such an issue. I choose to trust math more than some anecdotal data from a guy who pressure washes a maintenance free ring chain.
BTW...I would really like to know just what chain it is that is maintenance free....a man could make a fortune selling those! Most folks who "really" ride their bikes hard get no more than 1-1.5 years out of a good ring chain. Much less if they pressure wash them and do nothing else as far as maintenance.
If you want to discuss an issue, try to keep your cool and realise that every experince you've had isn't the written word on things. And if someone calls you on your information, try to offer up more than a verbal attack because that really shows your lack of debating skills and places you instantly at a disadvantage.
First, I didn't call you a liar. But as you provide more information it is obviously clear you have less than a clue about chain maintenance. And even less of a clue about me. I've probably owned more bikes than you can count.
Yes, it's ok....you can use your toes too, we won't call that cheating.
My point is that a 12 tooth sprocket is harder on chains than larger sizes. Some bike MFG's did go to a 12t CS sprocket on their stock offerings but their engineering staff realised it was a bad move and got away from that.
No, it's not going to FUBAR your fubsy bike. (what ever the hell FUBAR is...them fancy words really kinda stump me sometimes) It only will decrease the life of your chain and sprockets as opposed to running a higher tooth front. Usually dealing with mechanical issues there is math that can prove or disprove such an issue. I choose to trust math more than some anecdotal data from a guy who pressure washes a maintenance free ring chain.
BTW...I would really like to know just what chain it is that is maintenance free....a man could make a fortune selling those! Most folks who "really" ride their bikes hard get no more than 1-1.5 years out of a good ring chain. Much less if they pressure wash them and do nothing else as far as maintenance.
If you want to discuss an issue, try to keep your cool and realise that every experince you've had isn't the written word on things. And if someone calls you on your information, try to offer up more than a verbal attack because that really shows your lack of debating skills and places you instantly at a disadvantage.
Although I really don't have a dog in this fight nor care to because the argument here is absolutely rediculous, jaybird has offered no "math" or "science" to back up his side of the argument. Although you could pull out the callipers and take a baseline measurement between links on the chain when it's new and then measure it again after a certain length of time to get the exact wear, who really cares??? What is that going to tell you? Unless you use the exact same brand of chain with certified specs from the manufacturer and they provide you with a list of tolerances, your efforts are not only done in vane, but they provide little foundation on which to raise an argument in the forums. Without specs, the point at which you consider your chain to be worn out is completely subjective. And, you're incorrect or confused about the strain being applied to the chain by reducing the sprocket size up front. Given the formula for torque is:
tau = r F sin q
where:
r=radius of sprocket
F=force exerted by the countershaft (function of the engine/constant)
q (theta)=the angle between the weight to move (chain coming from rear to front) and the arm (line from center shaft to outside edge of sprocket)
In this sort of application, after you do the "math", you'll see that what you're saying will have very little impact on the wear of the chain from a torque standpoint.
tau = r F sin q
where:
r=radius of sprocket
F=force exerted by the countershaft (function of the engine/constant)
q (theta)=the angle between the weight to move (chain coming from rear to front) and the arm (line from center shaft to outside edge of sprocket)
In this sort of application, after you do the "math", you'll see that what you're saying will have very little impact on the wear of the chain from a torque standpoint.
Tom Ludolff
Member
- Oct 3, 2002
- 250
- 0
KnoxKDX: If that formula is correct, then F = tau/R*sin q. This says that reducing the sprocket radius will increase the force exerted on the chain. That would be what everyone is referring to I believe. Whereas, a larger rear sprocket gives the engine more leverage to turn the rear wheel reducing the force needed on the chain.
Tom L.
Tom L.
I stand by my experiances and you never explained your math. I will be on the trail with evidence that chain is holding up. I live in Northern California around Lake Tahoe. Pull out a topo sometime. Last Friday I went riding like I do most every Friday. I started the trip at 4800' elev. and capped off at 7280' elev. rode 40 miles and completed in 3 hours. (Including a nap that was interupted by a bald eagle announcing he had just caught breakfast from the lake I was snoozing at.) If you have a Magellan GPS, I could e-mail the track I recorded for this ride. Just to let you know I do ride and ride quite hard. I think, but not stating as fact, that the conditions I ride in can not be found in, Indiana. Maybe that has something to do with a difference in wear. So, as far as experiance goes, even if a smaller counter tooth sprocket results in more wear and force, it isn't enough to affect the chain Kawasaki saw fit to put on this bike.
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So, another theory wins out over experiance. And another post from someone who doesn't read well or has a low comprehension to what he is reading. I said ALMOST zero stretch, not no stretch. Now, someone please tell me what difference it makes to an 0-ring chain to put it up wet or not. I thought o-ring chains were sealed with o-rings. No lubeing, oiling, no maintenance. I think there are some of you out there wasteing your money on chain maintenance products for no reason.
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KelvinKDX
LIFETIME SPONSOR
- Aug 25, 2000
- 1,622
- 0
Ya'll are really getting worked up about this aren't you!
IMOP it should be harder on a chain (read: reduced life) to wrap around a smaller diameter CS than a larger one. The links have to rotate amongst themselves a greater arc. Is this enough to significantly reduce the chain life? I'm not totally sure. I've run both 12 & 13 fronts and i will say one thing. I've never had a chain last forever. The chain that i put on 2 years ago is still working but i'll admit needs to be changed and will be at the end of this season. My bike is a 99' and it's been through 3 or 4 (at least) chains. I use D.I.D. X-ring chains and Sunstar sprockets.
Ski - Jaybird usually know what he's talking about when it comes to lubrication and chains (maybe he is a totally crappy rider, has poor personal hygeine, stutters a little, has a hard time keeping food in his mouth when he talks, with a purdy bike and who is afraid of heights - but that's another matter). If you jump on people for offering their advice or knowledge then you will tend to not get it in the future.
Now enjoy the holiday and go out and ride - i would if i could but Eric has my case split apart as my transmission bearings decided to take holiday the same time as me. :(
IMOP it should be harder on a chain (read: reduced life) to wrap around a smaller diameter CS than a larger one. The links have to rotate amongst themselves a greater arc. Is this enough to significantly reduce the chain life? I'm not totally sure. I've run both 12 & 13 fronts and i will say one thing. I've never had a chain last forever. The chain that i put on 2 years ago is still working but i'll admit needs to be changed and will be at the end of this season. My bike is a 99' and it's been through 3 or 4 (at least) chains. I use D.I.D. X-ring chains and Sunstar sprockets.
Ski - Jaybird usually know what he's talking about when it comes to lubrication and chains (maybe he is a totally crappy rider, has poor personal hygeine, stutters a little, has a hard time keeping food in his mouth when he talks, with a purdy bike and who is afraid of heights - but that's another matter). If you jump on people for offering their advice or knowledge then you will tend to not get it in the future.
Now enjoy the holiday and go out and ride - i would if i could but Eric has my case split apart as my transmission bearings decided to take holiday the same time as me. :(
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Good advice KelvinKDX "If you jump on people for offering their advice or knowledge then you will tend to not get it in the future." Look back and see who started this trash talking. Jaybird took a shot at me, and I'm tired of KTM'ers thinking they are superior to KDX riders. The facts are what they are: I have not changed the chain on my 1999 KDX since new, I do no maintenance on it except wash it, it is still well within it's wear limits, I ride it at least 2 times a month since I owned it. Still haven't heard back on why my chain (lack of) maintenace is wrong with the o-ring chain and what maint. you all do to yours. I notice that no one with a KDX220 stock o-ring chain has voiced their experiance with the longevity of their chain. HOw about some feedback on 220 chain life from some owners.
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I just replaced the stock chain and sprokets on my dads 98 220 last season. I have no idea how much they were ridden on, but when I bought it, they were shot and I still rode it for a year without the chain, or sprokets breaking. These chain and sprokets were completely shot, and thats why I replaced them, but I was impressed at how long they went without breaking.
Is bigger better...? (J. Burke 5-01-03)
The question was asked:
“If I use two different sprocket teeth combinations to obtain the same gearing ratio, are the effects such as torque on the shafts the same with either?”
When I asked why, the response was:
"I want to know which is better to use; a smaller countershaft sprocket or a bigger one, to obtain the ratio I want."
Lets do some math. I will state some constants for the sake of ease.
20HP @ 5000 Engine RPM's
1st gear ratio of 15:29(1.93:1 ratio) which means at 5000rpm our CS is turning 2591rpm's (5000/1.93)
To figure torque of shafts, we need to first figure chain speed and working load.
The formula for figuring chain speed is:
Number of Teeth x RPM's / Pitches per Ft.
I will figure for two separate gearing set-ups that make the same ratio.
11t x 44t (4:1 ratio) and 13t x 52t (4:1 ratio) using #520 chain.
11t x 2591= 28,501
28,501 / 19.2(# of pitches per ft.) = 1484 Ft. per Min.
13t x 2591= 33,683
33,683 / 19.2 = 1754 Ft. per Min.
Now that we know the Ft. per Min of each sprocket we can now figure the Working Load of the two.
Working load is figured as follows:
HP x 33,000 / Ft. per Min.
(11t) 20 x 33,000 =660,000 / 1484 = 444.74 in. lbs. working load
(13t) 20 x 33,000 =660,000 / 1754 = 376.28 in. lbs. working load
Now we know the working load of each sprocket, we can figure the shaft torques.
Shaft torque for driving shaft (or CS) is as follows:
HP x 63,000 / RPM = CS torque (expressed in in. lbs.)
20 x 63,000 = 1,260,000 / 2591 = 486.3 in. lbs.
(this remains constant no matter the CS sprocket )
Shaft torque for driven shaft (or rear) is as follows:
Working Load x Pitch Radius = Driven Shaft Torque
(11t) 444.74 x 4.3805 (pitch rad. of 44t) = 1948.18 in. lbs. torque
(13t) 376.28 x 5.1755 (pitch rad. of 52t) = 1947.43 in. lbs. torque
What we see when we do the math using engineering formulas is that torque on the CS remains constant with a constant output of horse power. We also see that the torque on the rear shaft remains virtually the same between the two drive set-ups at the same ratio. (11/44 =1948.2 in. lbs. torque vs. 13/52 =1947.4 in. lbs. torque)
We see that the chain speed is different between the two gearing set-ups.
(11/44 =1484 Ft. per Min. vs. 13/52 =1754 Ft. per Min.)
What we also see different is the working load that each set-up creates.
(11/44 =444.7 in. lbs. vs. 13/52 =376.3 in. lbs.)
THIS is where the problem lies in going to a smaller CS. The additional working load is directly transferred to the chain links, and as a result, a smaller CS sprocket puts a greater load on the chain. We also have a lesser number or sprocket teeth to accomplish the same amount of work.
So both the chain and the sprocket teeth have to work harder, and as a result, wear out faster with the smaller front sprocket set-up.
Oh...and, Kelvin....I am learing to hold food in my mouth just fine, thankyouberrymush! :)
AND....skipro, you have a lot to learn about geography as well, pal.
You should actually stop while you are way behind. You sound really rediculous.
The question was asked:
“If I use two different sprocket teeth combinations to obtain the same gearing ratio, are the effects such as torque on the shafts the same with either?”
When I asked why, the response was:
"I want to know which is better to use; a smaller countershaft sprocket or a bigger one, to obtain the ratio I want."
Lets do some math. I will state some constants for the sake of ease.
20HP @ 5000 Engine RPM's
1st gear ratio of 15:29(1.93:1 ratio) which means at 5000rpm our CS is turning 2591rpm's (5000/1.93)
To figure torque of shafts, we need to first figure chain speed and working load.
The formula for figuring chain speed is:
Number of Teeth x RPM's / Pitches per Ft.
I will figure for two separate gearing set-ups that make the same ratio.
11t x 44t (4:1 ratio) and 13t x 52t (4:1 ratio) using #520 chain.
11t x 2591= 28,501
28,501 / 19.2(# of pitches per ft.) = 1484 Ft. per Min.
13t x 2591= 33,683
33,683 / 19.2 = 1754 Ft. per Min.
Now that we know the Ft. per Min of each sprocket we can now figure the Working Load of the two.
Working load is figured as follows:
HP x 33,000 / Ft. per Min.
(11t) 20 x 33,000 =660,000 / 1484 = 444.74 in. lbs. working load
(13t) 20 x 33,000 =660,000 / 1754 = 376.28 in. lbs. working load
Now we know the working load of each sprocket, we can figure the shaft torques.
Shaft torque for driving shaft (or CS) is as follows:
HP x 63,000 / RPM = CS torque (expressed in in. lbs.)
20 x 63,000 = 1,260,000 / 2591 = 486.3 in. lbs.
(this remains constant no matter the CS sprocket )
Shaft torque for driven shaft (or rear) is as follows:
Working Load x Pitch Radius = Driven Shaft Torque
(11t) 444.74 x 4.3805 (pitch rad. of 44t) = 1948.18 in. lbs. torque
(13t) 376.28 x 5.1755 (pitch rad. of 52t) = 1947.43 in. lbs. torque
What we see when we do the math using engineering formulas is that torque on the CS remains constant with a constant output of horse power. We also see that the torque on the rear shaft remains virtually the same between the two drive set-ups at the same ratio. (11/44 =1948.2 in. lbs. torque vs. 13/52 =1947.4 in. lbs. torque)
We see that the chain speed is different between the two gearing set-ups.
(11/44 =1484 Ft. per Min. vs. 13/52 =1754 Ft. per Min.)
What we also see different is the working load that each set-up creates.
(11/44 =444.7 in. lbs. vs. 13/52 =376.3 in. lbs.)
THIS is where the problem lies in going to a smaller CS. The additional working load is directly transferred to the chain links, and as a result, a smaller CS sprocket puts a greater load on the chain. We also have a lesser number or sprocket teeth to accomplish the same amount of work.
So both the chain and the sprocket teeth have to work harder, and as a result, wear out faster with the smaller front sprocket set-up.
Oh...and, Kelvin....I am learing to hold food in my mouth just fine, thankyouberrymush! :)
AND....skipro, you have a lot to learn about geography as well, pal.
You should actually stop while you are way behind. You sound really rediculous.
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I only started on this thread cause you went off on some tripe about how going to a 12 tooth was going to cost a chain and sprocket as opposed to a chain guide. While I posted actual experiance with the product.
Your comment to me about geography, are you telling me that Indiana has the riding and elevation conditions I see in the Sierra Nevada Mountian Range on the edge of Desolation Wilderness?
Tell you what, Jaybird....I'll stop writing replys and you stop writing as well, O.K.?
P.S. If you deside not to take my offer, kindly let me in on the geography lesson of Indiana, this one I've GOT to hear.
Your comment to me about geography, are you telling me that Indiana has the riding and elevation conditions I see in the Sierra Nevada Mountian Range on the edge of Desolation Wilderness?
I am quite clear here that I am not stating your area's riding conditions. So, while I admitted then I may have something to learn about geography, (obviously not from you) you need a reading comprehension lesson as much or more.
Tell you what, Jaybird....I'll stop writing replys and you stop writing as well, O.K.?
P.S. If you deside not to take my offer, kindly let me in on the geography lesson of Indiana, this one I've GOT to hear.
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If the information I have provided is not valid, then don't just call it tripe...disprove the information. I will be glad to accept that I'm all wet if you can indeed show me such. If it's your 5 day a week job, that shouldn't be too hard. Oh, wait....I see you've been editing your posts. Probably a good thing too.
Jaybird, if you're going to get all mathematical on us, at least use the right numbers.
You forgot the primary drive ratio. :silly:
I don't know about you but I'd be concerned with gearing that had my bike doing 2591 c/s revs (about 50mph) at five grand in first gear.
I actually agree with you and your formula (apart from the error - call me pedantic ;) ) is a great way of proving it.
You forgot the primary drive ratio. :silly:
I don't know about you but I'd be concerned with gearing that had my bike doing 2591 c/s revs (about 50mph) at five grand in first gear.
I actually agree with you and your formula (apart from the error - call me pedantic ;) ) is a great way of proving it.
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I like the math as well, you never know when it can come in handy. But the thing is, the actual wear on the chain is still going to be different from brand to brand, bike to bike, and location to location. And at the end of the day, when it's all said and done, you're the one who has to decide if your chain needs to be replaced and when.
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