Jump to content

Sprocket weights!!!!!

Recommended Posts

So I did some measuring of weight on three sprockets trying to find a reason of why I felt a drag on my 250 two stroke. Pics included. I was running a renthal 51 and the bike felt great with a 13oz flywheel weight.  Now I bent the renthal (broken chain guide) and went to a sunstar works z. When I changed I felt a massive drag, I mean like I was dragging something and please don't say I'm not good enough to feel it lol.  I have shaved my flywheel down to 10oz and it seemed to help a wee bit. So today I took the works z off and weighed it. The sunstar as you can see is a whole 11oz heavier (last picture and first picture) than the renthal. The stock sprocket (sunstar) is 12 oz but is only a 50 tooth. Both the renthal and sunstar works are 51 teeth.  Do not mind the first pic with the sprocket being off too far up top it was so I could take a pic. It was the same weight centered as it was in the pic.

Here is my dilemma. I want a new rear sprocket. And my two choices are IRONMAN 51 or RENTHAL 51.  I have talked to TM DESIGNWORKS AND ALSO DIRTTRICKS. They have reassured me that the IRONMAN is only 3OZ heavier than the RENTHAL or any other aluminum sprocket. I do not want to feel a drag anymore. I want what I used to have, that nice flow in where I could lug the bike in 3rd with no issues.  Could I actually feel 3OZ's?????  

 So $69 for renthal every season or $99 for IRONMAN and who knows how long of a time frame????? I race a250 harescrambles.  Any help with deciding would be nice thanks. Have a good one. 

IMG_1225.thumb.JPG.b94f68402961127ac33387739ce59159.JPG

IMG_1226.thumb.JPG.b79207f6867ac39029d491c21bbe3181.JPG

IMG_1227.thumb.JPG.84ed5019632968533358972970190d60.JPG

IMG_1224.thumb.JPG.52c6f9bc789dbb8f965fca53a11e4fea.JPG

 

Share this post


Link to post
Share on other sites
So I did some measuring of weight on three sprockets trying to find a reason of why I felt a drag on my 250 two stroke. Pics included. I was running a renthal 51 and the bike felt great with a 13oz flywheel weight.  Now I bent the renthal (broken chain guide) and went to a sunstar works z. When I changed I felt a massive drag, I mean like I was dragging something and please don't say I'm not good enough to feel it lol.  I have shaved my flywheel down to 10oz and it seemed to help a wee bit. So today I took the works z off and weighed it. The sunstar as you can see is a whole 11oz heavier (last picture and first picture) than the renthal. The stock sprocket (sunstar) is 12 oz but is only a 50 tooth. Both the renthal and sunstar works are 51 teeth.  Do not mind the first pic with the sprocket being off too far up top it was so I could take a pic. It was the same weight centered as it was in the pic.
Here is my dilemma. I want a new rear sprocket. And my two choices are IRONMAN 51 or RENTHAL 51.  I have talked to TM DESIGNWORKS AND ALSO DIRTTRICKS. They have reassured me that the IRONMAN is only 3OZ heavier than the RENTHAL or any other aluminum sprocket. I do not want to feel a drag anymore. I want what I used to have, that nice flow in where I could lug the bike in 3rd with no issues.  Could I actually feel 3OZ's?????  
 So $69 for renthal every season or $99 for IRONMAN and who knows how long of a time frame????? I race a250 harescrambles.  Any help with deciding would be nice thanks. Have a good one. 
IMG_1225.thumb.JPG.b94f68402961127ac33387739ce59159.JPG
IMG_1226.thumb.JPG.b79207f6867ac39029d491c21bbe3181.JPG
IMG_1227.thumb.JPG.84ed5019632968533358972970190d60.JPG
IMG_1224.thumb.JPG.52c6f9bc789dbb8f965fca53a11e4fea.JPG
 

IMG_1233.JPG

Share this post


Link to post
Share on other sites

Any drag you are feeling is most likely due to misalignment of the chain and sprockets rather than 3 ounces of weight.

  • Like 1

Share this post


Link to post
Share on other sites
Any drag you are feeling is most likely due to misalignment of the chain and sprockets rather than 3 ounces of weight.

Try 11ozs of weight look at weights. And no I'm not nuts 11oz is what the difference is. U think I'm misaligned? Okay, try 50 minutes of measuring lengths of swingarm bolt to axle bolt and from back of axle block to rear of swingarm like in videos on YouTube. I've done digital readings to tape measure readings to a taped on piece of string measurement all stating that I'm perfectly centered on the left and right axle block alignment. I'm telling you add a flywheel weight as well as a 11oz heavier sprocket and tell me you won't feel it. Bs.

Share this post


Link to post
Share on other sites

So you did the measurements and alignment correctly, I apoligize for my previous comment.  I just don't believe that you can detect a performance difference due to an 11 ounce difference in weight when compared to the total weight of the motorcycle.

  • Like 1

Share this post


Link to post
Share on other sites
So you did the measurements and alignment correctly, I apoligize for my previous comment.  I just don't believe that you can detect a performance difference due to an 11 ounce difference in weight when compared to the total weight of the motorcycle.

But don't forget a 13 oz flywheel weight too.

Share this post


Link to post
Share on other sites

Where does the 13 0z flywheel weight come in?  I thought you changed a sprocket and didn't like the results.

Share this post


Link to post
Share on other sites

I also have a 13 oz weight on too. I have read that a heavier sprocket can actually sometimes act as a flywheel weight in itself

Share this post


Link to post
Share on other sites

Okay, now I sort of understand.  A flywheel weight is connected directly to the crankshaft, call that 1:1 gearing.  After the primary gear reduction, the transmission gear reduction and the secondary gear reduction of the chain and sprockets you will need a much greater difference of weight than 11 ounces on either sprocket to notice it. 

Share this post


Link to post
Share on other sites

the flywheel weight is way different, thats directly attached to the crank and keeps momentum going when the RPM gets low.   the weight on the rear wheel is transfered through the clutch, chain, etc... so much lost energry and other sprung weight, that adding 11 oz weight alone to the overall system adds about .02% resistance.  a lubed chain? a over tightened chain?  over tightened axle nut?  now THOSE will add resistance.  an extra few ozs on the sprocket.. nah.

 

think of the mud build up on your rim, etc. do you notice that?  how about the diff between a HD and a XHD tube?    the 11oz is insignifcant.   some tires can vary by up to 4 lbs which is slightly noticeable. but not a sprocket IMO.  you wanna lose 11 ozs... ditch the valve cap lol.

 

whats really nuts is the fact that youre comparing any other sprocket to the ironman... come man. its not even a question on which is better by miles.

Edited by cdf450
  • Like 1

Share this post


Link to post
Share on other sites

I wouldnt worry about it. youre gonna run a junk sprocket just to save an insignificant 3 ozs?!?!?!  nothing is better than the iron man.

 

are you running a non o ring, lightweight chain?  youd be sick if you seen the drag/resistance that a chain creates.  or brand new wheel bearings vs 1 month olds...

Edited by cdf450

Share this post


Link to post
Share on other sites

Can you provide the primary gear ratio, the transmission gear ratios and the secondary gear ratio (counter shaft sprocket/rear wheel sprocket)?  Given these numbers I can prove, mathmatically, that you are crazy.

  • Like 2

Share this post


Link to post
Share on other sites
15 minutes ago, Wild Alaskan said:

lol get a lighter rear tire, it will make a much much more significant difference in the inertia of the rear wheel. 

yep. the further out the weight is the bigger effect it has. 11 ounce difference that close to the center of axis would have a very minimal effect. also the difference in weight of your sprockets it because two are aluminum and one is steel. I always choose steel, its stronger and lasts longer

  • Like 7

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×