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Best $46 or 367$ mod...45T rear sprocket!

84K views 347 replies 79 participants last post by  miguel 
#1 ·
Installed the 45T sprocket today.....best mod for the $($46 from Sprocket center). I was going to do a full 520 conversion, but couldn't justify $220 when my chain was in perfectly good condition. $46, however, was a no brainer. Didn't have to break the chain or remove the wheel. She now pulls like a beast...especially in lower gears. It's a must do!

Will
 
#290 ·
Its slightly better than stock, and yes it can wheelie more but all humans have a handy wheelie control device on the end of their right arms :) Its still too tall with 18/45 imo.

The bike feels flat and boring to me with the stock gearing, the 17/43 (very similar to 18/45) was a little better, but still didn't feel like a thousand should, i was still disappointed in the difference from the 675.
Now with 17/45 it actually has proper punch like a big bike should.
 
#293 · (Edited)
Well I've enjoyed reading this thread instead of doing work all morning. I was hoping to sanity check what I'm now planning to do...

Running an '07 S3, the chain and sprockets are well past their time so I'm thinking I move to a 18T (stock) front and 43T rear (which is stock for the later model S3's anyway). So this way I'm moving to "current standards". I also am not interested in having the wheel pop up on a whim in 1st and 2nd... a touch more pull (whether I notice it or not) moving from 42 to 43 will be enough for me.

Variables I can't account for are...
- The stock '07 chain is 106 links, so if I move from a 42T to a 43T is there a way to know what length I'll need?
- The later model S3's with the 43T also have a 190 profile rear tyre I think... I believe mine's 180... is having the 180 going to factor into the chain length I need?
- If the speedo is around about 6% high at stock, me moving to a 43T probably doesn't justify messing with the speedo calibration at all... my speedo will still be, what, 3-4% above actual speed... my odo will be a teeny bit off, showing less km's than I've actually done, but only slightly... is that correct?

I think I'll go with a 520 conversion too... not expecting any great change from it, but it sounds like a positive move and with the quality of chain/sprocket I'll get (DID, steel teeth etc) I don't expect I'll have any premature wear issues.....................

Thank You
 
#294 ·
...The stock '07 chain is 106 links, so if I move from a 42T to a 43T is there a way to know what length I'll need?
A general rule of thumb is 4 extra teeth, fit 2 links (you must fit links in pairs)
Simple way to think about it is that if sprocket has four extra teeth, the chain goes around approx 1/2 of the circumference on the sprocket, so in this case two extra teeth or two links.

For one extra tooth, you would need 1/2 a link's pitch in actual length - moot - std 106 will be fine
(I actually helped friend fit 45 to std 106 chain - it was close to the limit of adjustment but in spec - if changing chain also, definitely go +2 links)

The later model S3's with the 43T also have a 190 profile rear tyre I think... I believe mine's 180... is having the 180 going to factor into the chain length I need?
No

If the speedo is around about 6% high at stock, me moving to a 43T probably doesn't justify messing with the speedo calibration at all... my speedo will still be, what, 3-4% above actual speed... my odo will be a teeny bit off, showing less km's than I've actually done, but only slightly... is that correct?
You're counting wrong way - going to larger rear sprocket than stock makes error worse, not better.
 
#295 · (Edited)
Herbus, if you're going +1 on the back you shouldn't need any more links if you buy a new chain.

Can anybody tell me whether a 108 link chain would be suitable for a +3 rear sprocket before i order it? (or should i be going for a 110 bearing in mind how much slack these S3's like?)
EDIT: DEcosse, you're good! Answering my question before i've even asked it! Thanks!
 
#303 ·
This is way late but for the benefit of gear comparison it is very simple maths- the 42(standard for 2006) 17 combination is very close in final result to the 45 18 combination- would admire anyone with the riding ability to tell the difference between the two setups in a blind test ride situation.
42 17 2.470588235
42 18 2.333333333
45 17 2.647058824
45 18 2.5
 
#310 · (Edited)
This has been confirmed. I asked the tech this week about not having to change the speedo when I put the 45 tooth sprocket on. He confirmed that unless one changes the wheels, not the tires, the wheels, you do not have to worry about the speedo on the 2011 ABS model. I guess the tone ring must be hooked to the wheels? Anyways, he said I did not have to worry about the speedo being off.
 
#316 ·
Installed my 45t sprocket yesterday. A breeze with the pitbull stand on the opposite side as the swingarm. Then spent an hour or so this morning trying to dial in the speedo correction. I ended up at -8.3 and seem to be as close as I can get to my GPS. And finally spent the afternoon with an 80km or so ride; great mix of twisties and highway riding.

Gotta say that the 45t isn't as "night and day" as I expected from stock, but I'm very happy with it. Front wheel is certainly much easier to bring up in 2nd, but not even close to unmanageable. Yet highway riding still seems as good as before.

Call me a happy 45t customer.


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