FastBikerBoy
old hand
Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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Quick question on changing sprocket sizes. I've just bought a fireblade for the track (RRY) which should have 16/42 sprockets. I haven't looked to see what's on the front at the mo but it's got a 44 on the back.
If I want to change sprockets in the future at what point do I need to increase/decrease chain length? For example assuming the front is still standard if I put a 42 on the back is the same length chain okay?
I'm thinking it can be a quick way of changing gearing at different tracks but not if I have to start changing chains as well. Thanks.
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FBB
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makka
Carpal \'Tunnel
Reged: 13/05/2007
Posts: 2511
Loc: Jungle, Near Byron Bay, Austra...
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The sprocket will move back on the adjusters a small distance. Maybe about 15mm
If you have plenty to spare you should be fine.
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makka
drinking heavily
it's the only solution
Well, maybe meditation helps too.
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FastBikerBoy
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Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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Thanks makka, so the only consideration is enough adjuster movement either way.
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FBB
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makka
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Reged: 13/05/2007
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I'm pretty sure.
Maybe someone else knows more.
I just went the other way. 44 to 46 and everything is fine but my rear is now right at the front of the adjuster.
At least it wheelies off the throttle in first now.
Gonna put a 15 on the front when they arrive. Down from 16. That should put the adjuster back a little and make it a wheelie MONSTER.
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makka
drinking heavily
it's the only solution
Well, maybe meditation helps too.
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chappers
Carpal \'Tunnel
Reged: 31/12/2006
Posts: 5201
Loc: Mind your own business
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I tried fitting a 2 tooth extra rear and the chain is a smidge too short and I can't get the front sprocket nut off the fit the smaller front one altho with the added power don't really need to.
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If you Believe you will achieve,init.
Dizzee Rascal 2008.
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FastBikerBoy
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Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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It's something I've never messed around with before TBH. Can't really tell 'till I get on the track but it feels as flighty as hell and that's comparing it to an '05 ZX10 which aren't known for good manners.
I haven't even pulled the cover of the front to see what's on there, so I'll look at that next week. It just seemed like I went from 1st to top in a blur of gear changes and wasn't going that fast at the end of it, or not Senna straight fast anyway. I think it was geared for Cadwell which is much twistier and slower than Snetterton so I'm maybe thinking I need to get a standard rear ready to put on just in case.
The way it feels at the minute I'll be "Doing a Danni" (motoGP thread) 
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FBB
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chappers
Carpal \'Tunnel
Reged: 31/12/2006
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Start STD and work from there.
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If you Believe you will achieve,init.
Dizzee Rascal 2008.
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makka
Carpal \'Tunnel
Reged: 13/05/2007
Posts: 2511
Loc: Jungle, Near Byron Bay, Austra...
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I would check the front if I were you.
Each tooth off there is the equivalent of +3 on the back.
If you add a tooth or two there it will have even less effect on the chain but a massive difference to the excessive acceleration.
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makka
drinking heavily
it's the only solution
Well, maybe meditation helps too.
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chappers
Carpal \'Tunnel
Reged: 31/12/2006
Posts: 5201
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I'd also check head bearings, wheel bearings and suspension if the bike if that unstable.
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If you Believe you will achieve,init.
Dizzee Rascal 2008.
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FastBikerBoy
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Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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Okay, thanks both. I was thinking going back to standard and working from there. As you said makka I really need to check the front first. Thinking about it I think the width might be non-standard as well.
I'll have to have another good look round it when I get time. Thanks again.
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FBB
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FastBikerBoy
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Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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Yeah bearings are all okay, the suspension I haven't done anything with yet other than set the compression and rebounds back to standard. I've been waiting for an abbastand fitting kit to arrive so I can get the weight off them both and set the sag up properly.
The stability I think is a combination of the front being off the floor most of the time, a dodgy 'private road' and no damper. I was more concerned about how quick it was going through the gears. It certainly accelerates well but it ain't going to be any good if I'm on full throttle in top and only halfway down the back straight. I'd hardly get my 10 into top down the straight but that's much taller geared without a doubt.
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FBB
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FastBikerBoy
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Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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Right latest.
Front sprocket is a 15 to go with the 44 rear. So using the 1 on front is worth 3 on the rear, the end result is 5 on the rear. Anyone who thinks a ZX10R is lively at the front should try this thing!! This gave me a real lock to lock slapper yesterday.  At least I know why now, the front's barely ever on the ground, I reckon this'll wheelie off the throttle in every gear but probably has a top speed of a snail as a result.
So I've ordered a standard set 16 front 42 rear. Now does anyone understand gear ratios? The current set up 15/44 gives a ratio of 2.93 whereas standard 16/42 will give 2.63. Sounds good but I haven't a fucking clue what it means other than it wheelies like a mad thing with the first and be faster with the second. Is there some sort of idiot proof way of working out what ratio gives what top speed approximately or is it all trial and error?
I'm thinking going back to standard for my next track day at Snett on Friday (chain length permitting) would probably be best. I'm guessing somewhere between the two extremes would probably be better for there and would like to have a rough guestimate first rather than find out I'm bouncing off the limiter down the back straight flat out in top at 90 mph with a sore left foot from all the gear changing. Thanks for any advice.
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Cheers
FBB
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makka
Carpal \'Tunnel
Reged: 13/05/2007
Posts: 2511
Loc: Jungle, Near Byron Bay, Austra...
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How much would it hurt to change one at a time?
Go back up to 16 on the front and see how you like it.
I've never done anything other than test ride the 1000 sports bikes but I would guess that you would get all the acceleration you need from standard gearing.
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makka
drinking heavily
it's the only solution
Well, maybe meditation helps too.
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FastBikerBoy
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Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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Yeah thanks makka, I was thinking something similar myself. It's just so short at the moment it feels almost unusable, I might as well pull away in top and be done with it. I'll try changing just the front, and assess it at lunch time. Cheers.
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Cheers
FBB
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chappers
Carpal \'Tunnel
Reged: 31/12/2006
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Have you got Microsoft excel? I have a gearing calculator it's setup for my ZX6R ATM but you only need to change the parameters like gear ratios for each gear, Primary drive and tyre diameter to work out the different effects gearing has. For instance dropping one tooth on the front drops my top speed at 16,500 in top by 12mph to 174mph but if I added another two teeth to the rear (which I might later I have the bigger sprocket in my garage) it would drop it by 19mph to 167mph equivalent to dropping a whole gear in the gearbox.
If you don't have excel send me the page in the workshop manual that has the gear ratios, primary drive ratios tyre circumference and STD sprocket sizes and all the ones you want calculated and I'll do what I can then fax or email them to you.
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If you Believe you will achieve,init.
Dizzee Rascal 2008.
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FastBikerBoy
old hand
Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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Yeah that'd be great chappers thanks. I'll PM you my email at least I'll have a starting point then, thanks.
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Cheers
FBB
Remember kids don't try this at home
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makka
Carpal \'Tunnel
Reged: 13/05/2007
Posts: 2511
Loc: Jungle, Near Byron Bay, Austra...
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PM sent
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makka
drinking heavily
it's the only solution
Well, maybe meditation helps too.
|
FastBikerBoy
old hand
Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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Re-reading your post chappers and taking that as a ball park figure -1 on the front and +2 on the back equates to around 30 mph down, which on Snetterton's back straight will make a huge difference. I'll be overtaken by pushbikes. 
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FBB
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chappers
Carpal \'Tunnel
Reged: 31/12/2006
Posts: 5201
Loc: Mind your own business
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You miss read it's 19mph overall
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If you Believe you will achieve,init.
Dizzee Rascal 2008.
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FastBikerBoy
old hand
Reged: 08/11/2006
Posts: 1145
Loc: Norfolk surrounded by Yanks
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Yeah I see what you mean, thanks for the spreadsheet, very helpful, not only for top speed but all through the rev range is great. Should save a lot of trial and error.
I think as makka suggested I'm going to put a 16 on the front and leave the rear at 44.
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Cheers
FBB
Remember kids don't try this at home
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