chain hitting frame after front sprocket swap?

[tricky]

pardon me if this is a total noob issue... I just swaped out my front sprocket for a 15t. I adjusted the chain to the proper tension but now when I rotate the rear wheel I can hear a noise.. sort of like a clicking? it seems the top of the chain is rubbing against the frame, near where the swing arm meets the frame.

advice?

[BockinBboy]

I think there should be a rubber or plastic type of thing over that section of the swingarm that protects them from rubbing metal on metal there, because they are in such close proximity anyway.  But I don't know for sure if it normally touches that section or not with a 15t.  I'll let someone else chime in on that.

- Bboy

[adidasguy]

#5009

There is the black plastic chain guide. The chain lays on it - that's normal and why it is there. It actually has groves to help align the chain.

The clicking is probably chain not aligned or a worn chain with stiff links. If it did not do it before,
1. Check rear wheel for straight alignment of chain
2. If your sprocket has a shoulder, id you put it in backwards? That would cause serious chain alignment issues.
3. Insure you have the correct sprocket: if your old one had a shoulder on one side, insure your new one does. If it didn't, insure your new one doesn't.
4. Insure chain tension is correct. Too tight or too loose will cause noise.

Another thing - how many miles on the chain? A worn chain will make noise on a new sprocket. Normally you change chain and sprocket together as they wear together. Is your old sprocket very worn?

[werase643]

another issue to consider
you are probably checking the bike with it on the center stand.
if yes, the swingarm is fully unloaded with no weight on it, the shock is fully extended.
the swingarm angle is at a degree where the chain will ride on the pivot point of the swingarm.

if you sit on the bike the rear of the bike will squat to take the pivot point out of the rub equation.... depending on shock and your weight... it will squat 1-3 inches. 
if you have this problem while the bike is on the ground....disregard.

[tricky]

thanks to all for the replies. It was a long day of wrenching for me, my main goal was to replace my magneto gasket because it was leaking quite severely, so I figured I'd just get the sprocket done at the same time.

adidasguy - the sprocket is the right one, identical to the old one except for the tooth difference. The chain has about 14000 km on it so it is getting a little bit up there in the years. The front sprocket didn't look too badly worn though, but maybe I'm blind?    The chain still has life left in it though, so I was thinking I'd hang onto it for this season and then replace the sprockets and chain together in the winter.

werase643 - after I posted the message and really got to look at the situation, I started thinking along those lines. With me on it, I compress the rear enough that I think it gets clear. Hopefully 

And because a thread without pics is useless, here is a pic of the chain situation while on the centre stand. If you see anything bad going on, let me know

[slipperymongoose]

My rule of thumb here is replace chain and sprockets in one go so they all wear into each other as mentioned above.

[adidasguy]

#5017

I believe your swing arm does not have the plastic chain guide as you see on this swing arm. Hard to really tell. Can you verify if it is there? If it is, it is OK as the chain will glode over the plastic chain guide. If it is not there, you should get one and install it.