New Sprocket Please

Blog Date - 27 July 2014

I always know when I've a bike trip coming up. I start to fret. Oh yeah, Ren, the great two wheeled traveller, the adventurer...my arse. I've a trip to Scotland in the not too distant future and I estimate in the week we'll cover 1,500 miles. It's not so much, I reckon I do about that every month anyhow. It's not like Scotland is the remote backwaters of the Amazon rainforest or the Siberian Steppe. There's nothing to worry about, no passports, no EHIC, no border crossings (yet), no riding on the wrong side of the road and most importantly my RAC cover covers Scotland. Yeah, it'll be fine.

But, I am me and worry I must. I worry most about the bike. Will it break down? Have I checked everything? Is everything tight? While I am fretting the weather is nice so I think I'll inspect the bike, particularly the chain as it's getting a ways back in the swingarm now. The rear sprocket looks new still, no corrosion and the teeth are unworn and undamaged. The front sprocket, secreted behind the cover, is not...quite...right.

It's not shark-finned yet but there's signs of wear. And...curiously...weird wear. Unless I have my science wrong the sprocket is worn on the wrong side. This implies that the sprocket has been fitted once, worn a little then turned around!. It's an old trick I've employed myself to gain the maximum return on investment. It's also dodgy. It's more dodgy on a sprocket that is sided. By that I mean some sprockets are symmetrical on each side, the CBF 250 is not. As the writing is on the outside I figure it is now correctly fitted. As such this implies that at some point the sprocket was fitted the wrong way around and has now been flipped.

When I bought the bike there was 10,700 miles on it. It had a new chain and sprockets fitted, apparently. 10k on a chain? Maybe, if it's not been looked after. But the sprocket at the front is worn the wrong way. And it is NOT the original fitment. So...either the cowboy that fitted the new chain and sprocket used an old spare sprocket he had lying around...or...this bike has a lot more miles on it that the clock suggests.

If all this confuses you, fear not. The basis of the tale is that the smaller front sprocket, while not beyond use, is not giving me that warm, cosy, safe feeling. And the chain, presumably the cheapest chain the previous owner could find, is OK but still not making me feel all cuddly and cosy. Replace 'em, that's what I say. DID and JT now grace the transmission. Now...what else can I worry about

Old and new. If you're technical, note the wear on the old sprocket.

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