Lowering gearing and sprockets

[badbannedbiker]

My Nc29 struggles to pull anything close to top speed (should be 125-130 with a derestrictor box right) and only manages about 110. This is probably to do with aerodynamics due to the lack of fairing and high bars which isn't really a problem but I wondering if I can lower my gearing so it will still pull the top speed, but at a higher rpm with better acceleration (and hopefully a little more off the throttle lift over those hump back bridges. Where can I get different size sprockets and how much lower should I go? Front or rear sprockets should I change?
Cheers in advance

[tanuki]

by dropping teeth on the front or adding teeth to the rear will only decrease top speed and raise acceleration, you cant have the best of both worlds.

it sounds to me that if you bike will only pull to 110 then the restricor remover isnt working correctly, try removing it and going for a spin and see if the top end changes at all.

[badbannedbiker]

I'm fairly sure the speed box is functioning as when its unplugged the bike won't pull 105. I think its just the bike not being able to overcome the wind resistance from my frame. I no increasing acceleration means a trade off in top speed but as its not pulling max revs surely I can keep the same top end but just higher up the range nearer the redline, at the same time increasing acceleration?
Cheers

[tanuki]

just how big are you?

[badbannedbiker]

not very but as I said my 29 has no front or side fairings, just a round headlight and renthal sit up and beg bars

[Matchlessman]

My NC23 gets to the limiter quite happily in 6th and has -1 on the front and +2 on the back. apparantly it still does about 135 top end but ive never checked how accurate that is - the speedo still says 140 cos its driven off the front sprocket.

Your best bet would be to downgear it till you are happy. It does sound like it could be the restriction cutting in though, what happens when it gets to 110?

[badbannedbiker]

I struggle to hold on! It doesn't stop pulling as such but it only creeps up and I normally have to roll off due to lack of private road or aching shoulders. I think I'm going to try down gearing anyway if anyone can point me in the direction of a place to buy different size sprockets.
Cheers

[Matchlessman]

I got mine from a local bike shop but it was a bit of a pain cos they didnt appear in their standard parts books.

Graeme France would be your best bet, he's probably got the world and his dogs worth of sizes sat on the shelf.

make gradual changes, that way you can see how the bike feels.

[badbannedbiker]

Ok I'll try that. What size are they standard?

[Matchlessman]

The 29 is different to the 23, 29 has a 17 inch back wheel.

At a guess, the front is probably 15 tooth and thats the easiest to change (apparantly one tooth at the front is equivalent to 2 at the back)


Or, thinking about it, have a look at whats on the bike, you may find that its been overgeared at some point in its past. Counting the teeth at least gives you a baseline to work from.