sprocket and chain question

[guitarking135]

So I'm going to get a 14t front sprocket which is 2 down from stock. I need a new chain...very badly would stock size chain be good or would I be better to go a link or two smaller so that I have the adjustment room as it stretches? what is the stock chain I think its like 520 110? maybe somthing like that. Anyone?

[ineedanap]

If you're chain is already very bad and you're replacing that and the front sprocket it's a good idea to replace the rear too.   That way they wear together. 

You can't go "a link" smaller.  Chains have even numbers of links.  Stock is 110 links.  Running the stock 110 chain with a 14 would move the axle back .3 inches from where it would be with a 16 tooth.  Running a 108 with a 14 tooth would move the chain forward .3 inches from stock.  

.3 forward might not be possible, but .3 back is. 

Running the 110 with the 14 also has the advantage of less occurances of "same link same tooth" That's when the same link of the chain hits the same tooth of the sprocket.  It happins more frequently with some chain/sprocket combinations and results in faster wear.  It happins 3 times more often with 108 compared to 110. 

This can be found at gearingcommander.com   

[drewbytes]

Having recently gone to a 15t sprocket, I wouldn't recommend a 14t. 15t is probably the perfect compromise, IMO a 14t would just be ridiculous. Each to their own though.

[joshr08]

14/45 love it 112 link chain

[guitarking135]

the 14 will give me a better bottom end eventurally I'm going to change out the rear one. The sprockets aren't worn just doing it for performance reasons the chain needs to be replaced either way I just figured do it all at once ..

[fred]

If you're chain is already very bad and you're replacing that and the front sprocket it's a good idea to replace the rear too.   That way they wear together. 

You can't go "a link" smaller.  Chains have even numbers of links.  Stock is 110 links.  Running the stock 110 chain with a 14 would move the axle back .3 inches from where it would be with a 16 tooth.  Running a 108 with a 14 tooth would move the chain forward .3 inches from stock.  

.3 forward might not be possible, but .3 back is. 

Running the 110 with the 14 also has the advantage of less occurances of "same link same tooth" That's when the same link of the chain hits the same tooth of the sprocket.  It happins more frequently with some chain/sprocket combinations and results in faster wear.  It happins 3 times more often with 108 compared to 110. 

This can be found at gearingcommander.com   

The sprockets don't wear together. The wear on an individual tooth of the sprocket is a function of how many teeth are engaged at a given point and how often they are engaged. Since the front sprocket turns faster and has fewer teeth engaged, it wears a whole lot faster than the rear sprocket does. I believe GS Jack never or almost never has had to replace a rear sprocket in some insane amount of miles. Other people do the rear every other front sprocket. Check both your sprockets as described in the manual and only replace the ones that don't look good. Chances are your rear sprocket is fine...

[sledge]

Designing chain drives for optimum performance and reliablity is a science. In addition to poor maintainance, sprocket/chain wear is down to whats known as Chordal Action. Its an inherrent problem that cannot be engineered out and it has to be worked around and accomodated in the design stage. In simple terms the lower the number of teeth on a sprocket the more the chain is subject to speed variation as it engages and disengages. A figure of 2% is seen as the maximum allowed variation in speed for a well designed high-speed chain drive system. Anymore than this and the chain will see a dramatic rise in snatch and vibration and its lifespan and that of the sprocket and probably other components in the drivetrain will be dramatically reduced.

http://books.google.co.uk/books?id=BIJjtXB_qHQC&pg=PA131&lpg=PA130&ots=R8ONcFRzDL&dq=chains+chordal+action&ie=ISO-8859-1&output=html

Notice on the graph where the the line crosses the 2% mark and it becomes obvious why the Suzuki design Engineers chose to use a 16t sprocket as standard. You can also see the effect a smaller sprocket will have on chain speed variation.

[ineedanap]

I didn't realize my post implied that sprockets wear at the same rate.  That's not what I meant.  My point with "good idea to replace your rear, that way they wear together" was that putting a new stuff with worn out stuff will cause extra rapid wear of everything.  Fred cleared that up.  Thanks Fred.   Do what he said and check the rear sprocket before you throw new stuff on.   

[bill14224]

Sledge gives the scientific explanation of why I went to a 17-tooth front sprocket.  Better on the highway, and less wear and vibration to boot! 

When you increase the front sprocket size a little there is less sprocket wear, less chain wear, less rear tire wear, less vibration, less engine braking, and better mileage.  Many advantages, and only one disadvantage; slightly decreased acceleration.  Works for me!

To me the right front sprocket to use is the biggest one that still allows the bike to accelerate in top gear without being a slug, and for this bike it's 17 teeth.  It's all about efficiency and smoothness, man! 

[sledge]

yeah Bill,...........Its like most Engineering principles in that a gain somewhere, means a loss elsewhere. Its a trade-off, a smaller front sprocket will enhance performance but the downside is you will be replacing it sooner. In your case its reversed, you have lost the performance but the sprocket will last longer and be easier on the chain. The difference between a 17 and 14 tooth sprocket doesnt sound much but the graph shows it has a huge impact on the chain.

If you were to go much below 14 teeth on the front the vibration generated would make the bike practicaly unrideable.

[ineedanap]

apparently we hit the "viewing limit" of the google book link.  no more workee

[bill14224]

Sledge:

It doesn't sound like much until you do the division.  14 teeth is 17.65% shorter than 17 teeth.  That means instead of cruising at 5,000 rpm with 17 teeth you're spinning at 6,071 rpm with 14 teeth.  That's a big difference!

I would bet that if all the GS'ers went on a big ride together, by the time we got 100 miles into it, 98% of us would wish we had taller than stock gearing.  The other 2% would be just plain stubborn!

I knew after riding this bike for a total of 2 hours that I would be putting a bigger front sprocket on it soon.  Around town it's fine with the 16-tooth spocket, but on the expressway the bike was screaming, "gear me up!!"

[guitarking135]

thats true for long distance you want a bigger  gear ratio most of what I do anymore is cruise around town The 14t will serve me very well if I was making my bike a commutar well i would not have the stuff that I have for and on it. To each his on

[jeremy_nash]

I have a 14 tooth front  with around 2k miles on it.  it has the shoulder, so it will be good for your f model.   will take $15 shipped within the 48 continental states.  if interested, pm me