Going up a Tooth on my Front Sprocket

SANGER_A2

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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 intobikes.co.uk 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 black :thumbup:) 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:-
  • I have to use a little more gas when pulling off etc if I want the same acceleration (which isn't a big deal to me)
  • Engine breaking is much smoother now - especially when down-shifting. My speedo seems more accurate when using the GPS. No idea about the odo, don't really care that much TBH.
  • My first gear is more useful now and I stay in it for longer
  • I'm cruising at around 6000-6500 RPM on the motorway and my fuel-consumption has improved per tank.
  • The engine is much less vibey over all speeds - but is mostly noticeable at higher speeds - which I love.

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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bob808

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Re: Sidestand Mod for Lowered Bikes

Very good info. Thank you. But can you post the difference you got in fuel consumption? I am really interested in both ways, how much you save with 17 sprocket and how much you sacrifice with 15 sprocket. So if anyone else knows this...
 

SANGER_A2

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Re: Sidestand Mod for Lowered Bikes

Very good info. Thank you. But can you post the difference you got in fuel consumption? I am really interested in both ways, how much you save with 17 sprocket and how much you sacrifice with 15 sprocket. So if anyone else knows this...
I never had a 15t sprocket. Just the stock 16t. My last fuel refill was at 48MPG driving not at all efficiently with lots of WOT on slip-roads and pulling away from lights, driving at up to 85 on the motorway etc.

Before that, it was quite hard to find one. The only one I could find was 39MPG, but that was before I modded my airbox, upgraded my front tyre to a road pilot 2 & got a decat pipe for starters so it's not very accurate I'm afraid! It wasn't really why I did it, it was just to save the engine a bit and reduce the vibes really. I don't spend much on petrol a week so I'm not looking to be totally efficient or anything. I mod my bike for comfort, looks & pleasure. This was comfort.
 
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