Few places have Triumph sprockets off the shelf, but Suzuki and Yamaha sprockets can be found anywhere - so this might get you out of a bind in the event of catastrophic failure on the road... Also, if you like to play about with gearing, want to try a 520 chain conversion, or just want cheaper sprockets than Triumph OEM parts...
From the JT Sprockets website:
The rear sprocket (43T) on our bikes
to e.g. the Suzuki GSX-R600 (2001-2010)
and comes in sizes 40, 41, 42, 43, 44, 45, 47, 48 for 525 chains (stock)
- and in 42, 43, 45 for 520 chains
The front sprocket (18T)
is almost identical
to the Yamaha YZF R1 (1998-2017)
- it's slightly thicker, so you'll need a few minutes on a lathe if you want the locking washer to fit...
and comes in sizes 14, 15, 16, 17, 18 for 525 chains (stock)
- and in 15, 16, 17 for 520 chains
The very newest ('15-'17) 865 models also have 18T front sprocket for 520 chains
and 42, 43, 45 for 520 chains
fitted as stock.
Free Spirits offer an offset 19T front sprocket
if you want to run wider rubber - but only for 525 chains.
The Sprocket Center offer 16, 17, 18, 19 size front sprockets for both 520 chains
and OEM 525 chains
, and for the rear have 40, 42, 43, 44, 45, 46, 47 for 520 chains
and 41, 42, 43, 44, 45, 46, 47 for 520 chains
. Hunting around for GSXR/R1 sprockets will probably turn up still more sizes...
) offer light "Stealth" rear sprockets for the GSXR in both 520 and 525 size, so perfect for our bikes. Unfortunately for those of us on "this" side of the pond, the European site isn't as comprehensive as the USA one - we're better off looking at the USA site and then armed with the relevant part numbers going back to the European site...
My engine has a small patch of vibration between 4,200-4,500 rpm - but by using The Gearing Commander
I was able to "plan" my gearing to make this as unobtrusive as possible on Finnish roads (100kph in the countryside, 120kph on the motorway) - with a 19T front sprocket and 42T rear, the bars start to get a bit buzzy at 112kph but has totally cleared up by 125kph... Perfect! (If you don't mind driving a little over the limit...)