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Pros and Cons of gearing changes

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Mellow Matt
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PostPosted: 05:06 - 27 Feb 2010    Post subject: Pros and Cons of gearing changes Reply with quote

I've been reading a bit about changing the gearing on bikes by changing the sprocket sizes, but I'm still pretty new to it. Essentially is it right that if you put on a smaller front sprocket or larger back sprocket this means the wheel's turning faster for a given RPM? Meaning faster accelleration and slower top speed?

Are there any big pros and cons for changing the sprockets? E.g. I read that putting a smaller front sprocket on increases the load on the chain as it has to bend more to get around it, is this something to worry about?

Ta Smile
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Polarbear
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PostPosted: 05:27 - 27 Feb 2010    Post subject: Reply with quote

A smaller rear sprocket - Wheel turns more for 1 turn of the front sprocket so you will go faster for the same engine revs. Worse acceleration

A larger rear sprocket - Wheel turns less for 1 turn of the front sprocket so you will go slower for the same engine revs. Better acceleration

A smaller front sprocket - Same efferct as larger rear.

A larger front sprocket - Same efferct as smaller rear.

Those are the mechanics of it.

The problems come matching changes and effects and I don't know enough about them (and they are motorcycle specific) to advise.
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Deckx
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PostPosted: 08:36 - 27 Feb 2010    Post subject: Reply with quote

As said smaller front or bigger back lowers the gearing

I "think" one down in the front is same as 3 up on the rear.

I've done front one down on my track bike, completely transformed it as the original set-up was geared wrong for the track i use. Recently got a 41 back but yet to fit it ..

Not sure there is a huge advantage for everyday normal riding especially as it screws up your speedo, it will read higher and increase your milage (although you can get elctronic speedo healers)
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Kickstart
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PostPosted: 12:26 - 27 Feb 2010    Post subject: Re: Pros and Cons of gearing changes Reply with quote

Mellow Matt wrote:
I've been reading a bit about changing the gearing on bikes by changing the sprocket sizes, but I'm still pretty new to it. Essentially is it right that if you put on a smaller front sprocket or larger back sprocket this means the wheel's turning faster for a given RPM? Meaning faster accelleration and slower top speed?


Wheel is turning slower for the given rpm. Possibly better acceletation and lower top speed (but depends on the initial gearing)

Mellow Matt wrote:
Are there any big pros and cons for changing the sprockets? E.g. I read that putting a smaller front sprocket on increases the load on the chain as it has to bend more to get around it, is this something to worry about?


In theory the smaller the front sprocket then the more wear on the chain. However unless you go stupidly small I would expect the difference to be fairly nominal (expect you would get far more variation just from how well you care for the chain).

All that said, most of the time you will get exactly the same effect from just sitting in one gear lower. You can't do that in first, but I also doubt that you are using all the available throttle in first either.

All the best

Keith
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ms51ves3
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PostPosted: 13:52 - 27 Feb 2010    Post subject: Reply with quote

Deckx wrote:
Not sure there is a huge advantage for everyday normal riding especially as it screws up your speedo, it will read higher and increase your milage (although you can get elctronic speedo healers)


Unless the speedo is cable driven from the front wheel.
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Mellow Matt
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PostPosted: 00:41 - 28 Feb 2010    Post subject: Reply with quote

Ah cheers guys, got it mixed up.

I've just recently bought a TL1000R and the guy before me put a smaller front sprocket on (-1 tooth). I'm guessing the speedo will be out, does anyone know if this is the case with the TL?
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V2
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PostPosted: 01:37 - 28 Feb 2010    Post subject: Reply with quote

quite a handy website, im sure i saw it on here but ill repost it anyway!

https://www.gearingcommander.com/
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Rob W
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PostPosted: 03:15 - 28 Feb 2010    Post subject: Reply with quote

Mellow Matt wrote:
Ah cheers guys, got it mixed up.

I've just recently bought a TL1000R and the guy before me put a smaller front sprocket on (-1 tooth). I'm guessing the speedo will be out, does anyone know if this is the case with the TL?


Yes mate, it will be.

Not a huge amount, but it does have some effect.

Thumbs Up
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Alexio
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PostPosted: 03:52 - 28 Feb 2010    Post subject: Reply with quote

Rob ZX4R wrote:
Mellow Matt wrote:
Ah cheers guys, got it mixed up.

I've just recently bought a TL1000R and the guy before me put a smaller front sprocket on (-1 tooth). I'm guessing the speedo will be out, does anyone know if this is the case with the TL?


Yes mate, it will be.

Not a huge amount, but it does have some effect.

Thumbs Up


Surely it would also register less miles over the long term as well? He could have sold you a bike that has a thousand miles gone "missing" comparably for that bike (I know it's never entirely actuate).
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Kickstart
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PostPosted: 11:40 - 28 Feb 2010    Post subject: Reply with quote

Alexio wrote:
Surely it would also register less miles over the long term as well? He could have sold you a bike that has a thousand miles gone "missing" comparably for that bike (I know it's never entirely actuate).


Lowering the gearing will mean it will clock up more miles than it actually travels.

If you want to know the effects on umph then try the Bikegraph site in my sig. Enter the details of a dyno run and the gearbox ratios and it shows you the thrust at the rear wheel, and can show you how this changes with changes to the sprockets.

All the best

Keith
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Ghost
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PostPosted: 19:29 - 28 Feb 2010    Post subject: Reply with quote

Depends on your speedo drive, my ZXR has a speedo that's driven via cable straight from the front wheel, so it's always accurate and isn't affected by gearing. However if you've got a gearbox driven speedo it will be out.
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Mellow Matt
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PostPosted: 08:42 - 01 Mar 2010    Post subject: Reply with quote

After reading the manual it appears it's gearbox driven, ah well...
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supZ
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PostPosted: 10:40 - 01 Mar 2010    Post subject: Reply with quote

you can get 'speedo healers' to remedy inaccuraces caused by gearing changes on electrical speedos.

my track bike runs a -1 front and +2 rear which retains the original chain length for better drive but on a road bike unless your gearing is particular 'off' for your style i wouldnt bother changing but, but thats just me
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Mellow Matt
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PostPosted: 20:27 - 01 Mar 2010    Post subject: Reply with quote

Apparently it's a popular mod on TLs, I haven't ridden one with the standard sprocket so I don't know if it makes much difference.

I'll have a look into speedo healers, ta.
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spiderwheels
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PostPosted: 21:09 - 01 Mar 2010    Post subject: Reply with quote

supZ wrote:
on a road bike unless your gearing is particular 'off' for your style i wouldnt bother changing but, but thats just me


I agree. It depends on how and where you ride. You may find you end up changing gear more often which will ultimately slow you down.

Best to try your favourite stretch of road and see how you're using the engine. Smile
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Billy Balthorpe
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PostPosted: 22:22 - 01 Mar 2010    Post subject: Reply with quote

I had -1 front and +2 rear on my Ugly Streetfighter Blade. It was just a bit too much to ride fast on the road with, great for 3rd gear out of corner crossed up wheelies, but not actually for going fast. I was going on holiday with it and it felt like it was screaming a bit at cruising spped (90mph) so i went back to the standard front and it still wheelies for England, but not quite as bad on long motorway drives.
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