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Changing the gearing on your bike

Discussion in 'General Motorcycling Discussion' started by Kurtis_Strange, Nov 5, 2005.

  1. Hi Guys,

    I'm just reading up about my hornet on a UK site and there's a thread all about changing the tooth size on your sprockets which give you different gear ratios...

    Has anyone tried this? Are there any real benefits?
  2. Be the same as changing your diff ratio on a car i spose. Grab a shorter ratio to improve acceleration, or taller to improve fuel consumption and maybe top speed if theres enough power available..
  3. ok, so is it a common practice over here?
  4. Loz has done this on his hornet and sounds like he is happy. A lower ratio gear means you are going to be moving your maximum torque down to a lower speed, which means you are going to be taking off from the lights a bit quicker since you power band hits sooner. You MIGHT also get a SLIGHT increase of rearwheel torque.

    But its not all good things becuase you are loosing out on top speed and your speedo will be out. Not too much you can do about the top speed but you can get speedo healers (dubious reputation), relearn where the goal posts are or get a GPS or bike speedo to solve the problem of your speedo and Odometer being out. With the Odometer doing more distance than what is actually travelling you are probably affecting the resale value more than what you would otherwise.

    I was thinking about going down a few teeth with my change of chain and sprokets at my 30000km service on Thursday but it just seemed like a little too much hassle for me. But my bike is pretty much stock anyway.

    But this is all theory and perhaps may not be the truth of the matter.
  5. Seems to be.
  6. Yeah, the main two reasons I did it:

    1) Because even naked bikes are geared so tall (110-120k in first gear) that they're a pain in town. 3rd gear feels like it's revving too high at 60-70, 4th feels too low. I changed both front and rear cogs to downgear the bike pretty significantly and now I can use more of the gearbox around town. ome people prefer not to have to change gears.... I like kicking the gears around and feeling like I'm using them.

    2) Downgearing makes it easier for me to accelerate fast and do my crap wheelies. This is the stuff of everyday riding for me and I definately enjoy the new ratios.

    The speedo thing hasn't fazed me too much, odometer might be more of an issue down the track. And top speed? Pffff.... This thing still goes 250km/h without a bother.

    The main negative for me is that my large rear sprocket now means the chain hangs down onto my centrestand when the bike's at rest. But once I get on it and compress the suspension there's no problem... It just might be worth thinking about.
  7. Oh, and yeah there's plenty of info on Hernet ratios including a nifty calculator that shows you what difference a tooth or three will make to speeds vs revs over on the Hornet's Nest, which is where I'm sure you got the idea in the first place.
  8. yeah i'm perusing the nest now...hey speaking of centre stands, mine comes stock with a side stand which I can imagine could be a bit dodgy parking around town?

    I've been referred to an anderson stand which I might look into, but can you get a centre stand fitted to the 600, and is it advisable; eg any negatives?
  9. You don't always lose top end by reducing your front sprocket teeth. Many bikes will struggle to redline in top gear, dropping a tooth at the front may allow you to get into that zone and get there anyway. Speedo reading will change slightly.
    I'm with Loz, the loss in top end speed is a bit of a non issue. Not something you are going to miss unless you ride on the track competitively. Im looking at going from a 16t to 15t front sprocket on my next chain/sprocket change.
  10. Just dont drop it when putting it on the centre stand. :p How heavy is 600 hornet?
  11. 185kg with fairing. I'm not planning on dropping it but more worried about someone knocking it over or something
  12. Yeah, i definately wouldnt be worried about the drop in top speed, cause theyre probably wont even be any.

    The only thing id be considering would be the rpm on the highway in 6th and therefore the fuel consumption. Probably also a bit of a non issue with the bike, but ive got a 308 with a close ratio 4sp and shortly geared diff in the car and let me tell you that aint much fun on the highway :wink:
  13. Are you sure about those things? I'm not being definitive here, but logic seems to say that both those things are wrong. All you are doing is changing the overall gear ratios. A smaller rear sprocket will mean that more engine revs are required for one turn of the rear wheel, but the number of times the wheel turns per kilometer will stay the same. The only way you could change that would be to change the wheel size. In other words, if you rode one kilometer in 3rd gear the odo would show one kilometer, if you rode it in 6th the odo would still show one kilometer.
  14. That was my understanding of it also!! It doesn't matter what speed you are doing, 1 kilometer is 1 kilometer regardless as the revolution of the front wheel remains the same. As Incitatus said changing the Wheel size (read: Diameter will affect it). Hence why you have to program in the diamter of your wheel into those bike speedo's. The engine RPM/Speed should not be affected by a sprocket change because the wheel is still revolving around the same distance.

    That why when Ricer boys in there cars put 17-18" Mags on there little Suzuki Swift that were 13-14" Stock they end up with Speedo's out by up to 20km/h (a friend of mine) yet by dropping it a close ratio gear box the speedo remains the same.

  15. If the speedo takes its drive off the countershaft sprocket (as most bikes these days do) then yes, it will most definately throw the accuracy out the window.
  16. Deafwish has re-geared his Hornet 600 too, drop him a Pm and discuss it with him
    There is an after market centre stand available from the UK (there are frame carriers for it) but it's 119 pounds, and it'll cost that much for freight too, IMHO it's too expensive.
  17. Now that I can understand. It seems a pretty dumb way to do things though. If the speedo takes its info off the countershaft, you could just disconnect the chain completely and do 300kph standing still!
  18. Not if the speedo pickup is on the front sprocket, as I'm pretty sure it would be on the 600 Hornet.

    Aprilia get much props for using a Hall sensor mounted by the rear brake caliper for a speedo pickup; it counts the rear disc mounting nuts... very clever.

    GeePee bikes use a laser diode on one side of the rear disc, a photocell (or a CCD) on the other, both mounted to the caliper, and slots in the disc carrier. Together with a similar system on the front wheel, that lets them run traction control. Even cleverer.

    Either way, why are we having this conversation; shouldn't replies to the OP have been along the lines of, "Why ask about mods for a bike you haven't even ridden yet?"
  19. Well -its like this incitatus. Unlike BMW's, modern bikes have "horsepower" This causes the front wheel to lift off the ground when ridden in a "spirited" manner. Thus providing inaccurate readings if the speedo drive is taken from the front wheel. :wink: Taking the drive from the rear wheel also can provide gross inaccuracies. I personally have seen about 130km/hr on the speedo of my K bike whilst not moving in a foward direction. There was however clouds of blue smoke billowing from the rear tyre at the time :LOL: :LOL:
  20. Well I'm damned! I shall be taking my R1150R in to have that dangerous horsepower stuff removed immediately.