Gearing Recommendations for 630 SMS

[rocko]

I plan on changing my gearing but not sure which route I want to take.

If I understand correctly, going down one tooth on the front sprocket is about the same as going up 3 in the rear.

Which do you recommend? Up three on the back? Down one on the front? Something else?

I plan to ride 75 percent street, 25 percent track.

I thought of some pros/cons of each, let me know if you agree:

Down one on the front:
Pros - cheaper part, and don't have to get a longer chain
Cons - Smaller radius on front sprocket may increase chain wear, harder to install

Up three in the back:
Pros - easier to install than front, doesn't increase chain wear
Cons - more unsprung weight, may need longer chain, more expensive part

Thanks for any info!

 

[RDTCU]

Pros:
-Better acceleration

Cons:
-Higher RPM's on the highway.
I hit 5000 at around 72 with stock gearing, and that's a bit buzzy, but if most of your driving is around town, you should be OK...

What makes you say the front is harder to change? It's actually much easier as you have one snapring, and two cover bolts, then pop the masterlink off the chain and that's it...

 

[rocko]

What I meant by harder is higher torques involved. I never changed a front sprocket on my SV but I changed the rear sprocket. But I heard from other SV owners that you need a huge breaker bar because the front sprocket torques are much higher. I just assumed it would be similar on this bike. I have a cheapy torque wrench that only goes up to about 60 ft lbs or something in that range and I thought the front is usually torqued to in the neighborhood of 200 ft lbs.

 

[RDTCU]

What I meant by harder is higher torques involved. I never changed a front sprocket on my SV but I changed the rear sprocket. But I heard from other SV owners that you need a huge breaker bar because the front sprocket torques are much higher. I just assumed it would be similar on this bike. I have a cheapy torque wrench that only goes up to about 60 ft lbs or something in that range and I thought the front is usually torqued to in the neighborhood of 200 ft lbs.

Except on the 630SMS the sprocket isn't held on by a bolt and flange, it is held on by a snapring.
Here's a pic i just took on my phone of mine, pulling the shield back:

 

[rocko]

Cool so what tools do you need to take off and replace the front sprocket? Just some pliers?

 

[Ketek]

I've gone up 6 in the rear + new chain. So 44 tooth sprocket. Bike pulls like mad Highway and stuff like that sucks tho. But it's a supermotard.. I don't need no high speeds

 

[RDTCU]

Cool so what tools do you need to take off and replace the front sprocket? Just some pliers?

Good set of Snap Ring Pliers, don't fubar the snap ring with the wrong tool. You can find them at most auto parts stores for fairly cheap...
If you're careful and don't over-stretch the ring (just enough to get it off), you can re-use it, but if you go too far you should replace it.

 

[rocko]

I've gone up 6 in the rear + new chain. So 44 tooth sprocket. Bike pulls like mad Highway and stuff like that sucks tho. But it's a supermotard.. I don't no high speeds

Wow that rear sprocket must be as big as an extra large pizza!

So why did you go up on the rear and not go down on the front sprocket and keep your stock chain?

 

[rocko]

Good set of Snap Ring Pliers, don't fubar the snap ring with the wrong tool. You can find them at most auto parts stores for fairly cheap...
If you're careful and don't over-stretch the ring (just enough to get it off), you can re-use it, but if you go too far you should replace it.

Cool, sounds easy! I think i'm going to do the front sprocket

 

[motogo1]

Cool, sounds easy! I think i'm going to do the front sprocket

You have to take off the chain also, because of the interferance with the clutch housing. Still is easy, just an added step. I went with a 14. 5000RPM=65MPH

 

[Gardezy]

I went to a 43 rear on mine... if I did it again id go 42 anything is better than that stock gearing .
shit feels like its lugs to much with a 38

 

[TE 450 Pilot]

How big can you go on the rear and still keep the stock chain ?

 

[MrClean]

On my SM630 I swapped-out the stock 38t for a 40t. I probably could have gone to a 41 and still used the stock chain. With the 40 my highway cruising speed dropped from a maximum of about 80MPH to about 75.

Eventually, I put a 14t on the front and I'm still running the 40t on the rear. That combo puts the rear tire in almost exactly the same position as stock. Now I don't take the bike past 70MPH except for short bursts. But, it's totally worth the trade-off. The bike is way more fun down low.

 

[husky666]

15/42 and two more links in the chain. Bigger rear sprocket is better than a smaller front, the chain will live longer.

 

[tool46n2]

noob here, If I am going to go up to the 42t, what size chain do I need to get to accommodate, how may links? not sure what stock is?

 

[willie]

noob here, If I am going to go up to the 42t, what size chain do I need to get to accommodate, how may links? not sure what stock is?

Previous posts stated that you can run stock chain with 40t sprocket. If you still find 40 too high you can swap out the 15 front for a 14 and still use stock chain. Have used 14 and 15 t sprockets on various bikes and see no difference in chain life. 12 t sprockets are another story. Check out www.gearingcommander.com for combos.

 

[Gardezy]

noob here, If I am going to go up to the 42t, what size chain do I need to get to accommodate, how may links? not sure what stock is?

GET A 120 LINK CHAIN SIZE IT UP TO 112 OR 111 I used a 112 on a 43 sprockets once chain stretched a bit is sits perfect. hope that helps.

 

[tool46n2]

thanks for the info...taking a look at the gearingcommander site, looks like I would be happy with changing either to 14 up front or a 43. Will probably go with the 43 as I will be doing 90% riding in the city with some back roads.

 

[TCP]

A pro roadrace tuner once told me "small circles", meaning whatever gearing you run, set it up with the smallest size sprockets. Ex. go down 1T in the front vs. up 3 or 4T in the rear.

 

[rocko]

A pro roadrace tuner once told me "small circles", meaning whatever gearing you run, set it up with the smallest size sprockets. Ex. go down 1T in the front vs. up 3 or 4T in the rear.

My guess is for lower unsprung weight?

I went with the 14/38. Dealer says he thinks I could go lower, but that this setup is a good compromise for doing freeway riding. I'll tell you guys what RPM I am at on the freeway tomorrow.