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Old 02-10-2019, 06:09 PM   #1
zammer
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2007 GSXR 750 Chain length / Swingarm length

Hey Folks,

Track bike 2007 GSXR 750 that I bought with a 15 tooth front sprocket, stock rear. That's 2 teeth short on the front.

As I replaced the chain this weekend I noticed that it was a link shorter than the stock length one I bought from sprocket center. It's always had the adjusters set pretty far to the front (maybe 1" of adjuster). Now it's set pretty close to the back, maybe 80% of the way out.

I'm wondering what's the typical track guidance on these bikes for wheelbase and if I should go back and cut a link off to match how it was before. I know longer = more stable, less wheelie prone.. but never felt like it was particularly wheelie prone in the first place.

Thoughts?
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Old 02-10-2019, 06:22 PM   #2
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It's gonna stretch, or get longer, as time goes on. If it's at the limits of adjustability brand new, it's too long.
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Old 02-10-2019, 06:32 PM   #3
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I think there's enough there to account for stretching of the chain. More concerned about handling - some race prep setups prefer them all the way out or in to better complement handling characteristics of that particular geometry.

More wondering if I'll notice or care.

Last edited by zammer; 02-10-2019 at 06:41 PM..
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Old 02-10-2019, 07:08 PM   #4
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GSXR's generally like a long wheelbase (adjusters fully back), and raised ride heights front and rear. Keep in mind that the further back the rear axle is, the "softer" the back end will feel due to the greater leverage it has on the shock.
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Old 02-10-2019, 07:39 PM   #5
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uve ridden both setups. which one do u like more? which one is faster?

IMO, run it as long as u can stand. theres more time to be gained in fast corners because they are generally very long. extra stability should help u gain time in those corners. also, a longer swingarm flattens the squat curve which can help with rear grip and can reduce tire wear.

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It's gonna stretch, or get longer, as time goes on. If it's at the limits of adjustability brand new, it's too long.
not for a race bike. race chains get replaced long before they stretch noticeably. and u dont plan your setup based on what could go wrong - u plan it based on whats fastest.
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Old 02-10-2019, 07:53 PM   #6
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uve ridden both setups. which one do u like more? which one is faster?

IMO, run it as long as u can stand. theres more time to be gained in fast corners because they are generally very long. extra stability should help u gain time in those corners. also, a longer swingarm flattens the squat curve which can help with rear grip and can reduce tire wear.



not for a race bike. race chains get replaced long before they stretch noticeably. and u dont plan your setup based on what could go wrong - u plan it based on whats fastest.
Just put it on, haven't ridden it. It was pretty close to the front before but here it is now, has 2 tick marks yet behind the adjuster:

https://imgur.com/a/u8ljoRe

Bike is pretty high up right now (+15mm front, +8mm rear (at shock)) which has greatly lessened how much I need to wrestle it around the track. I finally enjoyed the setup last fall... after I started pushing it a little harder the bike came into it's own. At stock geometry it was like wrestling a bear.

Just wondering if I'm going to even notice what's basically 1 link length difference as a mid A group rider.

Last edited by zammer; 02-10-2019 at 07:54 PM..
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Old 02-10-2019, 08:09 PM   #7
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thats not long. u can still see some of the slot at the back. thats in the middle.

id bet that ull notice a difference. a longer chain ~= 16mm of axle adjustment. 1 tooth ~= 4mm of adjustment. i can feel 1 tooth if i make the change in btw sessions. a longer chain is 4x that and can likely be felt by anyone in A group.

random thing: u are running 15/45 on a 750? that seems awfully short. i run 15/43 or 44 on my 600s. your gear ratios are only a tiny bit longer but u have quite a bit less rpm to play with. so u are probably forced to run really high rpms into corners, which kills corner speed. have u tried going taller?
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Last edited by stangmx13; 02-10-2019 at 08:15 PM..
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Old 02-10-2019, 08:26 PM   #8
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So it's a stock chain with 2 down in the front, so that makes it 8mm back from stock, correct? Dunno if I'll like it or not but I'll run it for a weekend and see. When I said back I meant on the adjustment ticks not the slot, but good to know this isn't considered inordinately far back or anything.

Yeah, figured that would come up. I know people will say I'm slow but I never hit sixth on this bike. I max out fifth at t-hill and I actually like the shifting. I figured I'd drop one or two in the back at some point just for giggles and see but it doesn't bother me.

It's a weird bike overall.. I think the guy who had it before was a total dipshit. Lots of weird crap like that. Showbike with lots of bling but minimal thought for legit track mods... standard gsxr poser bro I guess.
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Old 02-10-2019, 08:47 PM   #9
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Quote:
Originally Posted by zammer View Post
So it's a stock chain with 2 down in the front, so that makes it 8mm back from stock, correct? Dunno if I'll like it or not but I'll run it for a weekend and see. When I said back I meant on the adjustment ticks not the slot, but good to know this isn't considered inordinately far back or anything.

Yeah, figured that would come up. I know people will say I'm slow but I never hit sixth on this bike. I max out fifth at t-hill and I actually like the shifting. I figured I'd drop one or two in the back at some point just for giggles and see but it doesn't bother me.

It's a weird bike overall.. I think the guy who had it before was a total dipshit. Lots of weird crap like that. Showbike with lots of bling but minimal thought for legit track mods... standard gsxr poser bro I guess.
15 45 is a good gearing. Thill probably works better with 15/45, and Sears Point with 15/46, oddly enough. That's due to the shift points mostly. That drive out of T2 and T6 is super important. I almost never use sixth gear, you really need a massive drive out of T15 at Thill to make it worthwhile. I have both sprockets but am too lazy to ever use the 46 and prefer the longer wheel base.
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Old 02-10-2019, 10:18 PM   #10
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15 45 is a good gearing. Thill probably works better with 15/45, and Sears Point with 15/46, oddly enough. That's due to the shift points mostly. That drive out of T2 and T6 is super important. I almost never use sixth gear, you really need a massive drive out of T15 at Thill to make it worthwhile. I have both sprockets but am too lazy to ever use the 46 and prefer the longer wheel base.
Interesting - I've thought forever it was a weird quirk that happens to work for me. I haven't seen anyone else run a -2/0 setup but glad to know I'm not the only one that thinks it works.

As always thanks for all your help.
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