Best to change front sprocket or rear?

[Shibumi]

I'm looking to increase acceleration by raising gear ratio, and thinking something like a 42 rear (165 pound rider).

Somewhere I saw something about front sprocket size and the load it places on the engine and the drivetrain, and can't find it anywhere. I could replace the front sprocket with a 16 to accomplish the same thing.


So what is the best to replace and for what reasons, front or rear sprocket? I have to have the rear off for a new chain, so that isn't a factor.

And as an aside, why is the 2008 Busa going to an 18/43 sprocket combo? What would be the advantages?

P.S.- Just for reference-



Gear Ratio Calculator

Front Rear Final
16 39 2.44
16 40 2.50
16 41 2.56
16 42 2.63
16 43 2.69

17 39 2.29
17 40 2.35 Stock
17 41 2.41
17 42 2.47
17 43 2.53

18 39 2.17
18 40 2.22
18 41 2.28
18 42 2.33
18 43 2.39

 

[boosted]

Go with the rear only. Easier on the chain and if your bike makes good power, it's much easier to fine tune with one or two teeth.

 

[Charlesbusa]

This is a useful website,



The rear is easier on the chain, but the front sprocket is cheaper. For Busas, most guys go up in the rear only.

With the '08 Busa having a 18 front, means you could go to a 17 front and not worry about the chain.

 

[HeloMech74]

I just went to a 42 tooth rear and kept the stock 17 tooth front. The difference was VERY noticeable. I would go with just the rear sprocket to make it easy on the chain.

 

[The Big Red One]

(Shibumi @ Sep. 15 2007,08) I'm looking to increase acceleration by raising gear ratio, and thinking something like a 42 rear (165 pound rider).

Somewhere I saw something about front sprocket size and the load it places on the engine and the drivetrain, and can't find it anywhere. I could replace the front sprocket with a 16 to accomplish the same thing.


So what is the best to replace and for what reasons, front or rear sprocket? I have to have the rear off for a new chain, so that isn't a factor.

And as an aside, why is the 2008 Busa going to an 18/43 sprocket combo? What would be the advantages?

P.S.- Just for reference-



Gear Ratio Calculator

Front Rear Final
16 39 2.44
16 40 2.50
16 41 2.56
16 42 2.63
16 43 2.69

17 39 2.29
17 40 2.35 Stock
17 41 2.41
17 42 2.47
17 43 2.53

18 39 2.17
18 40 2.22
18 41 2.28
18 42 2.33
18 43 2.39

Do the rear....I put a 16 front on my stock wheelbase/chain busa and lost most of my chain adjustment. It moves the wheel too far back

 

[chevelle]

We are close in weight. (i am 158) With a few lb's out of the bike,alum. subframe,late 1k wheels and a few other bits. 17-42 works well,but honestly i prefer 17-41 with higher cruise speeds.

As to your other question,the larger 18-43 sprockets spread the load out a bit better.

When i am using bigger nitrous jets i like using a 18-43/44 for peace of mind.

 

[BusaWhipped]

The more power you make, the larger the front sprocket you want to use to prevent binding. That's why the change from 17 to 18 on the '08. The rear sprocket change is to compensate for the bigger front sprocket. The factory is going to error on the conservative side of things.

 

[Shibumi]

Ahhhhhhh, NOW I get it- the chain doesn't have to turn such a tight corner with the larger front sprocket!

Okay, I'm thinking rear sprocket.

Besides, those Vortex hard coated black aluminum alloy are just back-wheel porn...

 

[Red05]

(The Big Red One @ Sep. 15 2007,15:30) Do the rear....I put a 16 front on my stock wheelbase/chain busa and lost most of my chain adjustment. It moves the wheel too far back  

Another good point about the 42 rear is that it sucks the rear wheel in a bit, about 3/8", shortening the wheelbase, which should make the bike turn a little more quickly.

 

[BusaWhipped]

If you are going with a 190/55 rear tire, the shortened WB may cause some clearance problems. Otherwise, you are GTG

 

[vman1300]

(BusaWhipped @ Sep. 15 2007,21:48) If you are going with a 190/55 rear tire, the shortened WB may cause some clearance problems.  Otherwise, you are GTG

+1!

 

[Poppy]

(Charlesbusa @ Sep. 15 2007,14:02) This is a useful website,



The rear is easier on the chain, but the front sprocket is cheaper.  For Busas, most guys go up in the rear only.

With the '08 Busa having a 18 front, means you could go to a 17 front and not worry about the chain.

Charles, Thanks for posting that link. Good information.

 

[Don Hardcastle]

(BusaWhipped @ Sep. 15 2007,20:48) If you are going with a 190/55 rear tire, the shortened WB may cause some clearance problems.  Otherwise, you are GTG

Couldn't you just put a chain on it with 113 links and solve the clearance issue when running a 55 series tire?

Don

 

[Charlesbusa]

(USN05LE @ Sep. 16 2007,07:26)

(BusaWhipped @ Sep. 15 2007,20:48) If you are going with a 190/55 rear tire, the shortened WB may cause some clearance problems.  Otherwise, you are GTG

Couldn't you just put a chain on it with 113 links and solve the clearance issue when running a 55 series tire?

Don

Yup.

 

[Shibumi]

(Charlesbusa @ Sep. 16 2007,10:25)

(USN05LE @ Sep. 16 2007,07:26)

(BusaWhipped @ Sep. 15 2007,20:48) If you are going with a 190/55 rear tire, the shortened WB may cause some clearance problems. Otherwise, you are GTG

Couldn't you just put a chain on it with 113 links and solve the clearance issue when running a 55 series tire?

Don

Yup.

That's what I will do.

Just got my 190/55 Quali...

 

[BA BUSA]

(Shibumi @ Sep. 16 2007,08

)

(Charlesbusa @ Sep. 16 2007,10:25)

(USN05LE @ Sep. 16 2007,07:26)

(BusaWhipped @ Sep. 15 2007,20:48) If you are going with a 190/55 rear tire, the shortened WB may cause some clearance problems.  Otherwise, you are GTG

Couldn't you just put a chain on it with 113 links and solve the clearance issue when running a 55 series tire?

Don

Yup.

That's what I will do.  

Just got my 190/55 Quali...    

+1 go with a 43 rear, 190/55, and just add a link or two  

****You don't have to add a link for the 43...ONLY if you go bigger on the rear...44 and up with a 17 front****

 

[Don Hardcastle]

This is sorta w/i the realm of this thread. I am doing a 1397 build this winter. Would it be advisable to go to 18/43 post build or stay at 17/40? The ratio is only .04 apart.


Don

 

[BA BUSA]

By the way a 43 rear fits with a stock length chain (112 links) and the 190/55 will clear the swing arm too...that's what I ran @ Miller two weeks ago

 

[Lamb busa]

(BA BUSA @ Sep. 16 2007,08:43) By the way a 43 rear fits with a stock length chain (112 links) and the 190/55 will clear the swing arm too...that's what I ran @ Miller two weeks ago  

Lamb too!

 

[BA BUSA]

(USN05LE @ Sep. 16 2007,08:42) This is sorta w/i the realm of this thread.  I am doing a 1397 build this winter.  Would it be advisable to go to 18/43 post build or stay at 17/40? The ratio is only .04 apart.


Don

Go with the 18/43...you'll get more life out of the chain with the added torque