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Going up a Tooth on my Front Sprocket


This is not at all an original mod, but its the first I've done for a while and I really love what it's done to my bike, so I thought I'd post about it here with a few pics & what you need to get it done. The inspiration comes from this thread.

I ride to work every day on the motorway. As well as making my tyres flatten off in the middle.  It means I'm sat at 7000+ RPM for ages with the vibes annoying my hands and use more petrol & stressing the engine more than I need to. The idea situation would be to change the top gear cog for one with less teeth, but from what I've seen that's pretty much impossible to buy & expensive to get fitted. This way is cheap and works well.

The stock front sprocket is 16 teeth and I bought an AFAM steel 17 tooth sprocket. I bought mine from for £14! Bargain. I could have got an aluminium one for less, but didn't really see the point in the weight saving and it wouldn't last as long as the steel. Plus the stock is steel too.

It's quite an easy mod to do, the hardest bit is getting the chain over the back sprocket with the new, larger sprocket. My chain has done 10,000 miles and has probably stretched a bit. I'd hate to try it with a brand-new chain!

Put the bike on the centre-stand & then the first job is to get the front-sprocket cover off. It's easy. You just need an allen-key or hex socket set (what I used). It's easier to just unhook the gear-change rod (mine is painted black) when trying to get the plastic cover off.

It's totally worth taking off the front sprocket cover at some point. Mine was totally full of muck from the road and my chain lube.I try to relube every week and clean the chain every month (or two).

Loads of crap inside the cover too - even after loads fell onto my garage floor! :D

You will need to make sure the bike is in gear to get the sprocket off or it will just turn and turn! You will need a socket wrench with quite a lot of length too (I used a 2m breaker bar and even then it was a struggle). I also sprayed WD-40 all around it and let it soak in before trying to get the sprocket nut off.

You will need to loosen the rear axle nut and turn the adjuster nuts to minimum, then you can remove the blocks it sits in. You need to do this to get enough slack on the chain to get the old sprocket off and fit the new one - unless you are going to break the chain - which I wouldn't recommend. I also took off the hugger at the same time - but this was to mod it...

Once the front-sprocket nut is off, you need to do quite a lot of jiggling to get the chain off it, then you can slide it off the bike. Time to give it all a good clean after that! I like paraffin as it gets the grease off well, is cheap and doesn't damage the paint etc (although I wipe it off after cleaning) 

Here you can see the sprocket cover, chain-guard and original front sprocket after cleaning with paraffin & then shampoo etc

Here is my shiny new sprocket (the idiots sent me a 16t at first and I had to get them to replace it!

I found the easiest way to get the sprocket on was to push the chain to the edges, slide the sprocket on and then put the chain around it . I may have had to put the back wheel on the ground for this & take the chain off the rear sprocket too. I can't quite remember, it was a pain though!

Then you can put the bike back together again. Make sure the threads of the nuts are totally clean and I used copper-grease for anti-seize on the rear axle-nut and locktite on the front-sprocket nut. The chain was pretty tight and I had to put it pretty much on the lowest adjustment to get the right play in it. 

After installation the bike was different all over:-

Overall totally pleased with this and when I have to get new sprockets & chain I will make sure the front is a 17t!


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