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Sprockets/chain upgrade

Discussion in 'Modifications and Projects' started by Nug-Nugget, Mar 25, 2014.

  1. Hey all,

    I'm interested in changing my sprockets and have a couple of questions. Just need your advice and opinions on a couple of things.

    My bike has done about 6,000kms. If I changed one sprocket, would I have to change the chain and other sprocket too?

    The standard teeth on the STR are 16T front and 47T rear.

    What would be the best combination for street riding, mainly commuting:

    -1 tooth at the front and standard rear (15T/47T) - would this be too aggressive for the road? and does this put more strain on the chain compared to going bigger on the rear sprocket? Would the revs be annoyingly high when cruising?

    -Standard front and +2 rear (16T/49T) - I hear this is good for street riding but the 49T rear is really hard to find and will have to be ordered from Italy. Would this give it enough punch at lower revs?

    - Standard front and +3 rear (16T/50T) - The 50T is a lot easier to find than 49T and can be found in many brands. I was told by a mechanic that this will have a similar effect to -1 at the front (15T/47T). I would need a longer chain with this combo.

    If I need to get a new chain I'm thinking of getting an X ring - are there any negatives to this compared to an O ring?

    I mainly commute on my bike so I'm usually in traffic. What I want most is better response and more punch on the lower end. Any advice would be much appreciated.
  2. Ignoring anything about RPMs, the one thing I've learnt the hard way with is make sure that the wheelbase remains stock. It's nice to change the ratio for accelerating but what you lose through incorrect wheelbase is horrendous.

    This is why most people go with -1/+2 which keeps it close to stock wheelbase. It actually ends up shorter than stock, if you go +3 it'll be longer. But both are in the ballpark. Chances are either will be more gearing than you wanted. I find -1 is ideal ratio for most bikes but throws your wheelbase out.

    Get onto - www.gearingcommander.com and have a play around. There's a wheelbase section at the bottom. Post up if you got any questions about how to use it
  3. #3 RRdevil, Mar 25, 2014
    Last edited by a moderator: Mar 25, 2014
    Forget the X ring and the O ring, most new chains don't have simple O rings

    Here's a picture

  4. #4 RRdevil, Mar 25, 2014
    Last edited by a moderator: Mar 25, 2014
    These days there are XW ring chains too

  5. hey mate,
    you don't need to change the chain/other sproket if you only do one and you get the same sproket for the chain (eg you stock have a 530 chain/sprokets, if you dont want to change the chain/other sproket ensure the new one is a 530 sproket).

    went to a 520 kit on the gsxr750 -1/+2 and haven't looked back, just get the strongest chain you can afford as well, i ended up going with an EK ZZZ (9,400 tensile strength) and my mate got one that was (i think) 8,800 tensile strength and his has already stretched but mine doesn't appear to have stretched much at all yet (almost 12months old).

    check out the kits at motomummy and also get a SpeedoDRD as well since this is obviously going to throw out your speedo.
  6. Why are u wanting to change in the first place? They can't actually need replacing surely
  7. #7 Nug-Nugget, Mar 25, 2014
    Last edited: Mar 25, 2014
    Ok so you're saying most people do -1 front AND +2 rear right? And that keeps it closest to stock wheelbase. Would that it make it very aggressive and revvy? It sounds like it is combining both of the options I'm considering.

    Thanks for that link, it looks like the differences in RPM are pretty negligible for -1 front or +2 rear. -1/+2 raises RPM the most by about 500rpm.

    You say -1 is ideal for most bikes, why? I take it that this will shorten the wheelbase, I'm not sure how badly this affects the bike.

    You've given me another thing to think about.

    Thanks for that. It seems the easiest and cheapest option would be just to change the front by -1. I'm only going by what I'm reading from others as I'm not very bike savvy. The negatives I hear are -1 at the front puts more strain on the chain and the gears are too short and too buzzy at cruising speeds.

    How did you find the -1/+2 combo? How did it change the way the bike went? Any negatives? I take it it had was smoother and quieter with the 520 chain?

    They probably don't need replacing. I'm just looking for a bit more punch low down, better response. Most of my riding is commuting and I'm often stopping and starting.
  8. The ratio is ideal, not the wheelbase. The 675s already have quite aggressive gearing from stock. I had -1 on my Daytona and didn't want any more, even on the track it was good.

    I used to love over gearing bikes but now I'm starting to go back the other way and my bikes are ending up a lot closer to stock.
  9. I've run both a -1 with stock chain/rear sprockets previously, was a nice improvement, slightly quicker on acceleration but again, running slightly higher revs while cruising etc. honestly it's really not going to make that much more difference with strain on the chain, stock chains are pretty strong anyway and with my setup, how the bike is tuned with all it's mods and how i ride it, so far i've not had a problem running a lighter chain. no real difference in noise that i can remember but then again i've got a full yoshi system on it and can't really hear much else :love: smoother not really, acceleration and throttle control is key there. negatives i guess is that since the engine is reving slightly higher when doing any speeds you'll use a little more fuel, but it's so minor i haven't really noticed, maybe 20kms less per tank (now getting about 185-200kms per tank, BP ultimate)

    -1/+2 combo for me is perfect, careful though if you go to this setup, the acceleration increase is quite significant over stock gearing. you will loose top speed, but really where are you going to do 300+ km/hr on the streets? at PI race track and broadford this gearing is very nice on the gsxr750.

    street riding with this gearing again is fine, it's just getting used to the extra acceleration that it provides, you'll end up adjusting your throttle control naturally to what you feel confident with and wont even notice it after a while and wonder why you didn't do it earlier!
  10. Damn that sounds really good. I was almost set on the -1 option but this has got me thinking. I don't have any tools to work with so I will get a mechanic to do the work and would feel a bit stupid asking them to fit a front sprocket. Another option is to start with the -1 and if that's not enough I can get a chain and rear sprocket later on. I'll just lose out on the labour.
  11. I went -1 on the front when I had a street triple and was a really good set up for me. As Justus said your speedo will be out. Get yourself a copy of Tune Boy (free software download - google it) and a $20 cable from eBay and you can do this yourself.
  12. You should be able to get a cheap 15T JT sprocket for for around $30, the mechanic wouldn't want to charge much to install it.

    That's the best way, try it out with the stock chain then see how the gearing and wheelbase feels
  13. It may sound good but you are on a Street Triple and he is on a Gixxer 750. Two completely different bikes. -1 on the front was about as short as I would have the gearing on my Street Triple. -1 +2 might make for awesome wheelies but I reckon I'd bounch off the limiter every time I twisted the throttle in first.

    And do what UDLOSE said, get a JT sprocket from a bike shop and try it out? Why do you have to wait for one to be shipped from Italy??
    • Agree Agree x 1
  14. It sounds like the -1 option is the way to go so I will probably do that, at least to try it out first.

    Deadsy - The only 49T rear sprockets I could find to suit a STR were Renthal and Sunstar. Renthal are out of stock and I could only find the Sunstar one from an ebayer in Italy.

    I'm not too worried about the speedo at the moment. The only times I really check my speed are with cops, cameras or school zones and it couldn't hurt to be a bit conservative at those times. I'm more worried about the odometer clocking up too many KMs.

    Northerner - not sure if I trust myself with that but thanks for the advice.
  15. Interesting. JT sprockets are the most commonly sold sprockets, most bike shops should carry them, but you seem to be correct your options are limited to 47t or 50t. The 15t front should be easier to get a hold of though.