Chains / sprockets cliff-notes for racing

So as I'm getting my 1199 race bike sorted out, no surprise I'm zoning in on gearing as something I want to change.

Correct me if I'm wrong, but the decision points I've identified are:
1) How many teeth to add/drop and from front or rear?
2) Convert to 520 vs. stock 525
3) Quick change carrier vs. stock


Can anyone speak to #1 and #2 and how important they are?
I know the rear is quicker to swap

It looks like if I JUST change the front sprocket, this could be a $35 job...or if I go with the 520 conversion kit, it could be up to $500 (not counting extra sprockets for different tracks)


Keep in mind that I'm not at the WSBK level of riding, nor do I have the budget. I'm an amateur that can *maybe* make the expert bump this season with some practice, some luck, and a good setup. While this is something I thought about in converting the 1199 to a race bike, I wasn't expecting a $500 bill for it... I could probably dig up the money, but I'm hesitant....

I'm using gearing commander Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator to play around with numbers...It looks like a 14 tooth front is as far down as I can go in the front, and probably wouldn't have to change the chain (my gut feel is that when we get into chain replacements, thats when I start thinking about a 520 conversion, if people think that's the way to go)

I found the 520 conversion kit that JarelJ posted in another thread:
AFAM/DID 520 Chain and Alloy Sprocket Kit | QC51A1199C

As far as #3....
I've never geared a bike for a track before, and I'm not 100% sure how to go about it....in addition to thinking about overall top-out, do I need to mentally try to adjust my shift points to make sure I don't wind up between gears in a key corner? I'd hate to give myself more torque only to find out I now have to make shifts in funky places...

I'm also going to post on the local racer's forum for the track, but this bike is different enough from what anybody else is running that I bet

From what the head of the racing school at that track has said, MOST bikes like to be topping out in 5th gear there, which I've also heard elsewhere as a rule of thumb for most tracks.

I race a very tight track (NHMS / Loudon) - I ride a more open track almost every weekend I'm not racing (NYST). Obviously, I want to optimize for the track I race on, but it would be nice to have a setup that works at NYST (or an extra rear sprocket that I can swap if the same setup won't work for each).

This past race weekend at Loudon, I was pulling a lot of people on the straight, and the one time I got it down like I wanted to AND happened to look down at the indicator, I was in 4th gear.... Which means I'm using 3-4 for the entire track, with the exception of the very tight chicane coming onto the straight, where I believe I'm grabbing 2nd...

Charliem90 said:

Racing isn't cheap. Be prepared to spend money to spend time on track.

Click to expand...

Oh, I hear you - and I do. Sometimes you get hit with a lot of unanticipated things at once (see my thread on geometry/suspension). But there good ways to spend money and there are bad. Just trying to figure out what the best bang for my buck is. For instance, instead of upgrading to a $1,500 Termi slip-on so I can fit a belly pan on a bike that already makes more power than I need, I was able to fab one up out of fiberglass (with MrBrettBaker's help) that works with the stock exhaust. I'd rather spend my money on other things - like good suspension.

I race on only 1 track and ride another, so if, for instance a 14 tooth front would get me where I need to be on the one I race, I'd probably just spend $35 and be done with it, for the time being. Then if and when I get my laptimes down to where that 2 tenths of a second I lose by coming onto the straightaway 2K rpms from optimal is meaningful, then I'll upgrade. On the other hand, if the only thing that is going to get me close is going to be a new front, new rear, and a chain, I'll probably grab the 520 conversion kit and be done with it, maybe buy an extra sprocket for the track I do trackdays on.....then expand my sprocket selection as I add tracks, or find a need to fine-tune.

Chain length

Ok, so I've pulled the trigger on a 520 conversion (for a couple reasons, for better or worse I've done by ordering parts from different places and now I'm down to ordering the chain).

I am going to 14/42 (see explanation below).

My main question is chain length - it looks like 106 is the right # of links for people going with 15/41, based on a couple threads here. So does that mean I should go with 108 links?

In either case, how much will I be affecting the geometry by changing the gearing (with the 108 vs 106 chain length playing into that, assuming that either would work within the adjustment ranges).



I am at the top of 4th at the end of the front straight at NHMS on stock gearing (15/39) so I plugged that into gearing commander and assuming similar speeds, I'd be at the top of 5th at the end of the straight if I go with 14/42.

Hopefully that will have me using 3-5 instead of 2-4. The places I'm using 2nd it's really just a touch too low, but 3rd is too high. So I'm hoping that since 3-5 are spaced closer together, 3rd will be in the sweet spot on those turns.