17/30 or 18/32 sprockets? Replacing drive train.

[JayR]

Lots of great information regarding gearing on multiple threads. This one has a diversity of opinions, all great insight.

http://www.xs650.com/forum/showthread.php?t=1125

I am considering buying an 18/32 (or 31?) front and rear sprocket with new 530 chain from Mikes. OR a 17/30 setup.

Question: the gearing difference between the two is almost zero as nj points out in his post. Other than having to remove the shift shaft guard on the 18t front sprocket is there a reason to go with one or the other?

The late great XSJohn recommends retarding the TCI with some of the lower tooth counts - (his post # 6). Would that apply to any gearing change other than my stock 17/34 do your think?

Thanks for any insights you can share, grateful as always.

 

[fredintoon]

Hi JayR,
like you say, there ain't much difference in the gearing.
The one good reason to go with 17T instead of 18T is that the 18T set-up lets the chain gnaw at the shifter shaft and that can't be a good thing.

 

[Phail]

I went with the 18/30 combo and love it since I have to ride down the freeway for 50 miles anytime I want to go into town. It's 70mph and they are raising it to 80mph now.

Anyway, I tried it with the 17/30 once and didn't like it. Went back to the 18/30. I don't feel like it's slower off the line and if there is traffic I have to ride the clutch anyway not to run into people.

I rode from LA to Reno 70-80mph for 8 hours and it was totally fine.

I never removed the guard and just let it self clearance. No problems so far. I have about 10,000 miles on it.

I only weigh in at 150lbs also. So that might make a difference.

 

[Rockin Rolla]

Hello Phail! I WOULD LIKE TO USE THE 18/30 TO, But I dont know what size of chain am I need for that. I have an origoriginal 1976 typ 447 MODEL by the wa, and now I have 17/33 on it. Is there any chance that I can use the old chain?

 

[fredintoon]

Hello Phail! I WOULD LIKE TO USE THE 18/30 TO, But I dont know what size of chain am I need for that. I have an origoriginal 1976 typ 447 MODEL by the wa, and now I have 17/33 on it. Is there any chance that I can use the old chain?

Hi Rockin Rolla,
the #530 chain link size is identical and the chain's length will most likely be OK.
But don't do it.
Old chain eats new sprockets and old sprockets eat new chain.
Replace sprockets and chain as a set and they'll wear in together for the long haul like an old married couple.

 

[Phail]

New chain is like $30. I'm not sure if the old one will still fit. My bike is in no way stock.

 

[Rockin Rolla]

Thank you for your help guys! So I know that a new chan would be the best but I bouth mine nowadays, but I dont like it with these 17/33 spokets, so I wnt to go 18/30. That is why I dont want to spend for a new one. The other problem is that I dont remember wich size I have 520 or 530. How can I measure it, or whats the way to get know it? I know i have 104 chain links, so I have to cut 2 out to go 102, what will fits the 18/30. Am I right?! Please help me To ger know what size of the chain I have, and how much links I will need?

 

[nj1639]

Thank you for your help guys! So I know that a new chan would be the best but I bouth mine nowadays, but I dont like it with these 17/33 spokets, so I wnt to go 18/30. That is why I dont want to spend for a new one. The other problem is that I dont remember wich size I have 520 or 530. How can I measure it, or whats the way to get know it? I know i have 104 chain links, so I have to cut 2 out to go 102, what will fits the 18/30. Am I right?! Please help me To ger know what size of the chain I have, and how much links I will need?

530 is the normal chain size for a stock bike.
Once you put the sprockets on you can tell how many links on the chain to remove and depending on the sprockets used you may not have to remove any. Won't know untill you put the chain on.
I weigh around 180lbs........85 kilo?
I found that for my weight the 17/32 sprocket combo is the best. 18/32, 18/30, 18/29, 17/30 and 17/31 combos will have you lugging around corners in 2nd gear or dropping the transmission into first gear on those slow turns.

 

[irristeve]

I run 750 re/phase 17/32 is where mine's at tried 18/32 17/30 etc. if your mainly doing flat h/way work maybe 17/31, mine went slower & used more fuel on 17/30 which is a sure sign of over gearing

 

[fredintoon]

- - - I dont remember wich size I have 520 or 530. How can I measure it, or whats the way to get know it? I know i have 104 chain links, so I have to cut 2 out to go 102, what will fits the 18/30. - - -

Hi Rockin,
the only difference between them is that #530 chain has 3/8" width rollers and #520 chain has 1/4" width rollers.
Measure your rear sprocket thickness.
If it's 1/4" thick, #520 chain will fit.
If it's 3/8" thick it needs #530 chain.
#530 chain will run on #520 sprockets but I wouldn't recommend it.
It may be that the 104 link chain will still work on an 18/30 set-up if you move the axle back towards the end of it's adjustment. Or maybe not, but check before you chop the chain shorter.

 

[pamcopete]

Here is an Excel spreadsheet that shows RPM vs MPH for all combinations of sprockets, wheels, tires and gears.

REVS vs MPH

Click on the yellow (orange?) cells to reveal a pull down to select the numbers you want .

 

[Rockin Rolla]

thank you for your help guys, now I am going to measure the thicknes of the spocket to find out what size of chain I have. By the way I would like to get higher top speed for highway ride, because after I leave the city, riding is annoying... If you heve any other ideas to get better higway road experience, please help me!

 

[fredintoon]

- - - I would like to get higher top speed for highway ride, because after I leave the city, riding is annoying... If you have any other ideas to get better highway road experience, please help me!

Hi Rockin,
you don't mean "Buy a faster bike" right?
I'd switch the sprockets to 17/30 or 32 as the highest useable ratio, despite others succeeding with them an 18T sprocket does have clearance issues, especially if used with a heavy duty chain and ALL o-ring and x-ring sealed chains use the heavy duty chain's larger side plates.
There's also installing the MikesXS "overdrive" transmission gear which reduces the transmission's internal high gear ratio to reduce high gear RPM.
Try carefully balancing the carburetors to reduce engine vibration.
Re-phasing the engine will reduce the vibration if you want to take the effort and expense of doing that.
Your least-cost option is to slow down on the highway and enjoy the scenery.