Replacing Just the Rear Sprocket

[cromanyak]

I know that when you get a new chain your supposed to get new sprockets, but what if just your rear sprocket is worn? Do I need a new chain and front sprocket too or can I just do the rear?

[Wu-Viffer]

I was under the impression that you should always change both sprockets. Even if one isn't 'worn', it's probably grooved a bit for the chain you currently have. The chain and sprocket kits are a good deal, and it really isn't much more money to get everything. Changing the front sprocket is, of course, more of a pain in the butt.

[Lgn001]

From a technical point of view, you are SUPPOSED to change the entire set. Me, I inspect the sprockets with a magnifying glass and see if there are any problem areas to be concerned with. I always lube the chain at 400 - 500 mile intervals, and depending on the circumstance, wash it with kerosene no less than every 1500 miles and as often as every 500 miles.

I occasionally rip through all the gears, and I accelerate as rapidly as possible when the times and places seem reasonable. But a lot of my riding is straight line, getting from point A to point B at fairly constant speeds.

So my drivetrains tend to last a good while (15K-18K per chain, 30K-35K sprockets). I typically go through two chains per sprocket set, and even then the sprockets are in good shape. I replace them just because I know there is wear I can't see, and I always use steel, no aluminum.

It really comes down to cleanliness and riding habits, from my perspective.

[PARedVFRRider]

Well now, I can't speak from experience on my cycle, but I know that on my mountain bikes, I never change a chain without changing front chainrings and rear cogs. The reason why is that as the chain stretches and the sprockets wear, they stay somewhat compatible until the sprocket (rings, cogs) is completely worn out or the chain snaps. I've done the new chain on somewhat worn sprockets a few times on my MTB and within a week I was buying chainrings and rear cogs. The chain just kept jumping over the cogs when under load. I also tried the reverse when I ripped up my front chainrings and put new ones on with a stretched chain and it was almost as bad.

Now that is with peddle power, so I would recommend that you change everything if one or the other is worn out. It only make sense to avoid issues.

[Lgn001]

PARed, how many miles or hours do you figure you put on your mountain bike chains/gears before they are worn? Just curious, because it sounds like you ride it a lot.

I should have mentioned in my previous post that my chains aren't really in terrible shape when I replace them, for what it is worth. I am not arguing the merits of replacing the entire set, just pointing out what I have done...

Oh, and cromanyak, if your rear sprocket is visibly worn, you front one probably is too. Darn, I kinda missed the whole point of you question. Sorry about that!

[PARedVFRRider]

I do ride quite a bit and it really varies depending on the type of riding and conditions. If I ride a lot of technical trails and such with a good bit of grinding hills, log hops and I do that in wet muddy weather or a bit of stream crossings the equipment tends to fail more quickly. Lately with the weather we have been having the bikes have been covered in mud when I get home, even if it hasn't rained or snowed in days. The low areas of the trails just hang onto the moisture this time of year. Frozen at night, thaw during the day, etc. I ride about 4 to 5 days a week, no more than an hour a day. I use XTR equipment so it last a wee bit longer, but I will replace the full setup on both of my Rocky Mountains bikes once things dry out early this summer. The fact that I have two bikes and ride them both pretty frequently allows me to go a little more distance between changes. In the past it would be twice a year or sometimes more frequently, but this year I think I can get by with one change in early summer when things dry out.

I also didn't ride this year in October, November or December so that probably helped with me being able to wait till Summer to switch out some new gear. I picked up the VFR in October and pretty much all of my free time in those months was spent riding the VFR (I've put 5000 miles on it since mid-October). In January I realized I had put on 10 lbs and I needed to get back to my old ways! So now I split free time between the VFR and the Rockies! That is once the kids take the free time they deserve!

[RVFR]

Yep, Chain and sprockets my friend. if one is showing wear the other ain't far behind.

[nozzle]

Why wouldn't you change both sprockets? It is hopefully not the cost of the front sprocket, esp. when compared to the tires, chain and other expendible maintenance items.

It might be the pain to get at the sprocket - it takes some time, but it is not "hard", just some more screws.

So maybe you could inspect it, but to inspect both sides well you'll need to remove it (there goes one excuse). Maybe it's fine, but what if one tooth is worn and doesn't match the new chain well? What happens?

What happens is your new chain will wear out faster. as everytime the tooth and chain engages the bad fit will deform/stretch the chain. Since the front sprocket has less teeth than the rear, you'll get the bad match more often. Is it worth saving the coin? (approx. costs from motosport.com ~$30 for the front sprocket, $60 for rear, $100 for chain, or $150 for a set) That is your choice.

I'd replace both sprockets with the chain.

[cromanyak]

I was really just looking to save money. The front sprocket and chain seem like they're in decent shape, but I'm no expert so I guess I'll just go ahead and get the set. I've got an 86 VF500F. Any recommendations on where the best deals are. I've already got the front sprocket and chain off so I might as well. Can I get one already riveted together? Thanks for all the replies. I really appreciate it.

Chris

[VT Viffer]

I've never seen a motorcycle chain that came pre-riveted... How exactly would you install it???

As a matter of fact, how did you get the old chain off without cutting it? I know this is not something I can do (without tremendous amounts of disassembly) on my '96 VFR750...

[cromanyak]

I just bought the bike a few weeks ago. The chain looked pretty dirty so I pulled it off to clean it. I just had to pull the swingarm off. Not too difficult at all on my bike. It's 86 VF500 though. I don't know what it would be like on a newer bike.

Chris

[flameface]

My Kawa bikes always had endless chains (OEM). You had to remove the swingarm to install a new OEM chain. Master links back then were not as strong as what you get nowadays.