Gearing/Chain Length Question

[tls25rs]

I think I have a grip on this but figured I would throw it out there for you more experienced dirt bike people.

I bought a new chain and sprockets for my dirt bike, the rear sprocket went up one tooth in size and the front stayed stock. 49T and 14T for information sake. When I went to install the chain I shortened up the wheelbase as much as I could by sliding the rear wheel as far forward as I could in the swingarm slots.

When I was measuring the chain to cut it to length, it became apparent that with the wheel as far forward as possible I would not be able to get the chain to a point where I could make the cut without a ton of slack in the chain, just under two links worth of slack to be exact. That being the case I cut the chain at the longer length and then used the adjusters to take up the slack in the chain to the factory reccomendation for slack.

My concern/question is that this puts the rear wheel pretty far back in the slots in the swingarm effectively lengthening the wheelbase of the bike which I would think would have some affect on the handling of the bike, Is this a normal thing? Would I have been better off going up two teeth (only did the one because it was in stock) and therefore have the two additional links compensated for by the larger diameter of the ring?

In summary, did I do something wrong by making it so that the rear wheel is pretty far back in the adjustment slots or is this something fairly normal depending on the sprocket combinations that are being used?

Joel

[korndogg]

I don't get it. Why not cut the chain at the shorter length and then adjust slack with the adjusters? Or is that what you mean by "cut the chain at the longer length" = cut it as short as possible even though not as short as you would have liked?

[gregp]

"My concern/question is that this puts the rear wheel pretty far back in the slots in the swingarm effectively lengthening the wheelbase of the bike which I would think would have some affect on the handling of the bike, Is this a normal thing?"

Pretty mush normal. Yes.

"Would I have been better off going up two teeth (only did the one because it was in stock) and therefore have the two additional links compensated for by the larger diameter of the ring?"

Well, I would not recommend sacrificing your gearing target for the sake of chain fitting convenience.

"In summary, did I do something wrong by making it so that the rear wheel is pretty far back in the adjustment slots or is this something fairly normal depending on the sprocket combinations that are being used?"

No. The difference is handling/suspension operation will be negligible, unless you are a Pro, and extremely sensitive to your bike set up.

[SSearchVT]

On a dirt bike the position of the axle in the adjusters will not be noticeable. The travel in the adjusters is usually less than 3 inches on a swingarm with a pivot almost 20" away going through over a foot of travel.

If the slack is correct, and you've got room to go back (the chain will stretch) you're fine. What does the manual call out for number of links? One tooth extra on the rear doesn't increase the diameter enough to require a longer chain...

[tls25rs]

= cut it as short as possible even though not as short as you would have liked?

This is a good way of saying what I did yes.

Pretty mush normal. Yes.

Well, I would not recommend sacrificing your gearing target for the sake of chain fitting convenience.

No. The difference is handling/suspension operation will be negligible, unless you are a Pro, and extremely sensitive to your bike set up.

Glad that it is fairly normal.

I didn't really have a gearing target per se' more just what they had in stock and I did want to go a little larger on the rear sprocket so the 49T fit both requirements I had.

I am definitely not a pro and didn't think that I would notice it but would prefer the shorter wheelbase if I can, no real debatable reason.

If the slack is correct, and you've got room to go back (the chain will stretch) you're fine. What does the manual call out for number of links? One tooth extra on the rear doesn't increase the diameter enough to require a longer chain...

Slack is set to the factory manual and there is still a good amount of adjustment slot left so I'm not too concerned, more curious.





As far as number of links I am pretty sure it calls for a 120 link chain but if the installation of a new 120 link chain with a 14T/48T combination puts the rear axle at the front of the adjustment slot in the swingarm than adding the one tooth on the rear sprocket would likely require the addition of a link. Seeing as you can't add just one link, because the master link wont work correctly if you do, two links must be added to the chain so that the master link installs as it should.

On a 520 chain each link is 5/8 of an inch long (just looked this up now to clarify for myself) so by adding two links the chain winds up 1 1/4 inches longer than it was. To take up 1 1/4 inches of chain length, even with the larger diameter sprocket, I would think that the rear axle would need to be moved pretty far back in the adjustment slots. If I remembered my Jr. High School Geometry better I would probably try to figure it out.

Thanks for the replies. It is making me think that what I figured out last night will be fine.

Joel

[DuncanMoto]

www.gearingcommander.com

The most awesome online app for chain and gearing.
It tells you your different wheelbases with 3 different setups you plug in.

[tls25rs]

Checking out the gearing commander site is helpful. I may need to revisit this tonight and see if I can take out those two extra links and bring the rear wheel forward. We'll see I guess.

Joel

[R7]

I've found that if you're that close to the back of the adjuster with a new chain, you can usually remove the extra links after a few rides

[tls25rs]

Along the lines of what I was thinking as well Mark.

[seth399]

Ya, like said, I would go with what gearing you want over wheel placement. High level riders/teams adjust that wheel specifically but for everyday riding who cares. I like mine farther back because my bike wheelies too easily out of corners/on starts.