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Biff
19th November 2005, 01:41
Front or back?
How many teeth should be dropped from the sprocket? Front 1 and/or back 3?
Chain wear?
By how much would the speedo be thrown out?
I guess there would be an increase in the bikes indicated v actual Ks travelled? By how much?
What do you think?
Ever done it?

Sniper
19th November 2005, 07:06
What you planning to do, more touring or more racing?

To my knowledge, changing a rear sprocket doesn't change the way your odometer reads. Miss Sniper has a larger sprokett on the back but that is because he did alot of touring and it helped with the fuel economy and wasn't revving the shit out the motor.

From what it sounds like, you want to change both sprocketts to allow faster accelaration, but less top speed? Better controlibility in traffic? In which case, you are looking at maybe taking 1 out the front and 2 out the back. Something I read a few weeks ago made it sound like you don't need to change the front sprocket, but the way my mind works, its proberbly a good idea.

If you need a hand, let me know, but I'll find that article on sprocket changing and email it to you.

Kickaha
19th November 2005, 08:13
What are you trying to do, raise the gearing to lower the revs at whatever speed you cruise at or are you wanting to lower it so you get faster acceleration??

changing the front is easier,make it bigger for taller gearing,smaller for lower gearing,I tend to run the biggest front I can find and change the rear sprocket instead though as bigger sprockets give the chain a easier life


Ever done it?
Yes,on just about every bike I've ever owned

have a look here
http://www.sportrider.com/tech/146_0008_gearing/
http://faq.f650.com/FAQs/GeneralChainFAQ.htm

Ixion
19th November 2005, 09:38
Done it on lots of bikes. Used to be the case that manufacturers listed a range of sprockets and you took your choice.

Are you wanting higher gear - lower revs at crusiing, like having a 7th gear. But acceleration will suffer a bit (only the first bit) and you may need to be delicate getting under way.

Or the reverse - lower gearing for real fast traffic light action (though on a big bike that may just mean more wheel spin). But buzzy on the open road, like riding everywhere in 4th.

Or are you thinking of fitting a sidecar?

Either way, easy way is to remember that overall bikes are geared down. And front sprocket is smaller than rear. So going the same way makes for lower gearing (reduce front or increase rear). Going contra is higher gearing(bigger front, smaller rear).

If you have a choice it's best to lower gearing by increasing the rear size, raise it by increasing the front. Just because a smaller front sprocket means a tighter curve for the chain which can mean more wear (not much, though, and not always)

Won't affect your speedo unless it's gearbox driven . Front wheel or rear wheel driven is OK

Main reason I've done it has actually been to move a vibration point around. Sometimes you used to get (back when bikes vibrated like mad) a real bad vibe just at the speed you liked to cruise at. Changing the gearing would move it up or down.

I've known people who had two sets of sprockets - put one on for around town , and change to the other for touring. If you do that it's a good idea to change both front and rear sprockets - Add one to the front, drop one from the back. That way your chain stays the same length.

MSTRS
19th November 2005, 09:42
What you planning to do, more touring or more racing?

To my knowledge, changing a rear sprocket doesn't change the way your odometer reads. Miss Sniper has a larger sprokett on the back but that is because he did alot of touring and it helped with the fuel economy and wasn't revving the shit out the motor.

From what it sounds like, you want to change both sprocketts to allow faster accelaration, but less top speed? Better controlibility in traffic? In which case, you are looking at maybe taking 1 out the front and 2 out the back. Something I read a few weeks ago made it sound like you don't need to change the front sprocket, but the way my mind works, its proberbly a good idea.

If you need a hand, let me know, but I'll find that article on sprocket changing and email it to you.
Eh....wrong!! Whatever you do with the front sprocket, must be opposite x3 on the back. Lower the front or raise the back for quicker acceleration/lower top speed. If you want to tour, do the opposite. Speedo will be affected if it is gearbox driven, but not if it is front wheel as on the older bikes.

Ixion
19th November 2005, 09:58
You don't *have* to change both sprockets. Just changing one is perfectly good practice (rear is larger so it offers more granularity). But if you only change one, you will need to shorten or lengthen the chain, which may be a problem on modern sprotsbikes with silly endless chains.

MSTRS
19th November 2005, 10:07
You don't *have* to change both sprockets. Just changing one is perfectly good practice (rear is larger so it offers more granularity). But if you only change one, you will need to shorten or lengthen the chain, which may be a problem on modern sprotsbikes with silly endless chains.
Correct. I also tend to agree that going smaller on the front does put more stress on the chain (much tighter 'turnover') but the chain slack can probably be made up thru the adjusters. Whereas by going 3 teeth on the rear for the same effect will mean more/less links on the chain.

Sniper
20th November 2005, 15:03
Eh....wrong!! Whatever you do with the front sprocket, must be opposite x3 on the back.

My apologese. I was wrong, thanks MSTRS

MSTRS
20th November 2005, 15:16
My apologese. I was wrong, thanks MSTRS
U R welcome. I wouldn't like to think that you went out and spent a chunk of cash changing sprockets only to find you'd gone the 'wrong' way. Easy way to remember is drop a tooth on the front = drop a gear.

T.I.E
20th November 2005, 15:25
this bites. as my cbr is gear driven and i wish to change the gearing on my machie without altering the speedo. this i am working on.
change the rear than the front. less of a stress in the drive system and also it's not drastic.

White trash
20th November 2005, 15:33
If you go up three on the rear and down one on the front you'll be near enough to perfect Biff.

Motu
20th November 2005, 16:34
I always change the gearbox sprocket,because it's easy and cheap.A rear sprocket is more expensive,but I might change the rear to fine tune between front sprockets.I've got 2 gearbox sprockets for the XT,3 for the DT,have gone down to an 11 front and up to 50 rear on the TLR200,but really want to go to a 9/44,but 9 tooth are hard to find.The DT has a gearbox driven speedo,which is stupid for a dirt bike,so I have a front wheel driven mechanical job for adventure rides where you need to use the odo.

In days of yore it was the engine sprocket which was changed,gearbox sprockets were behind the clutch....they would even change clutch drums too.

Biff
20th November 2005, 19:13
Thank all.