No not on mine my Ducati dealership who fitted mine said its not necessary, but I have the stock rims & tyres ..mine goes like stink !
At just shy of 10,000 miles the gearbox sprocket on my bike is showing signs of wear with the teeth beginning to look a little hooked, not surprising since it turns about twice as quick as the rear. The chain and rear sprocket are still good so I decided just to replace the front one and while I was doing so to try out a 14t. In looking for a replacement I ended up having an interesting email conversation with Chaz at B&C Express. It appears that the JT sprocket (JTF742) is wrong for the Supersport with an incorrect offset moving the sprocket centre outwards by 1.85mm. The same sprocket had been offered by JT Sprockets as a 520 conversion for the 1098 which is when this error was discovered. The Renthal 433-520-14 (or-15 for the 15t version) is correct for our bikes. If you have fitted a JT sprocket the chainline is out. I don't know the situation for the Esjot sprockets.
Absolute rubbish...my dealership fitted me a 14JT front cog & there is No problem at all & my chain is spot on & not out at all...So go back to your drawing board & play some more. PS... i have let JT know you are crabbing their products
Fair enough. Not my drawing board. This was the information provided by B&C Express who are generally well regarded as a supplier of chains and sprockets and don't usually get their facts wrong. I now have the Renthal sprocket and it conforms with their drawing. It is very possible that the JT Sprockets drawing is wrong but their sprocket is correct. Maybe someone with a JT sprocket can compare it with JT's drawing. I will also suggest that over the length of the chain, something like 70cm between centres, side to side play between the sprocket teeth and the chain links could allow for seemingly perfect alignment. The clue would be wear on one side of the rear sprockets and the opposite side of the front sprocket.
Its not nice to crab JT Sprockets on the here say or info from a rival company, its not my style anyway So you have now fitted a Renthal 14T have you ?
From previous experience with Ducati's, +2R is generally in the sweet spot for most and +3R for the Panigale. For the SS, you can get a 46T or a 47T combined with a PCD-4 Quick Change sprocket carrier here: https://sprocketcenter.com/street-s...version-steel-rear-quick-change-sprocket.html
B&C Express are not a rival company. They supply both Renthal and JT sprockets and others. This is from their emails when I enquired about a sprocket: Thank you for your enquiry. I have looked at the listings for the 939 Supersport front sprockets and have to say that currently we cannot offer to supply one to you. Looking at the JT sprocket listing, they claim a JTF742.15 is the correct item. On further investigation, I have found that the JTF742 front sprocket is also listed as the 520 race conversion for the Ducati 1098. This allowed me to then look at the Renthal listing for the 520 race conversion for the Ducati 1098. The sprocket that Renthal produce is different to the sprocket that JT produce. I know that the Renthal front sprocket produced for the 520 race conversion for the 1098 Ducati is correct. This means that the sprocket JT list is incorrect. It also means that I am unable to trust the JT listing for the 939 Supersport. I hope my lengthy explanation is clear enough. If not, please get back to me. Regards, Chaz Sales Dept B&C Express Ltd And also: The problem that I have come across is the JTF742 is not the same sprocket as the Renthal 433-520 So if we look at a known Renthal listing, namely the 520 race conversion for the 1098, then I am seeing a conflict. I have no doubt that the information I was given was supplied in good faith and as far as B&C can see there is a conflict in the information provided by the 2 suppliers. In their experience the fitment provided by Renthal has proven to be correct and understandably they did not want to sell me a sprocket which may not be 100% right.
The 1098, Multistrada and Diavel have the same offset and uses carrier PCD-3 The Panigale 1199~V4, Monster 1200 and 939 Supersport have the same offset and uses carrier PCD-4 These carriers can accommodate 520, 525 and 530 chain width. Front sprocket must match of course.
IME, Derek is one of the most knowledgeable and helpful contributors on here. He is not given to “crabbing off” products. If he is issuing a warning about a product, you can be sure there is a good reason for it.
Thanks O@Old rider. Let me be quite clear about this. I had and have no intention of "crabbing" any manufacturers products. I was trying to pass on what could be useful information, which I'm sure @Sooty might have understood if he had read my post properly. I haven't yet swapped over the sprockets as I've had plenty else to keep me busy but when I do I will be comparing measurements between the OEM and Renthal sprockets. It would be useful if someone else could do the the same with a JT sprocket.
Derek in did read your post properly & it sounded to me like you giving "here say" & negative information regarding the JT Sprockets on here that hasnt been proven....not good in my book ! end of
Thanks for the support Jeremy. Some people, it seems, are not interested in information if it appears to conflict with decisions they have already taken.
I replaced the rear sprocket and the cheap Regina OEM chain at the first 600 miles service. Increased the gearing (i.e. leverage by +2R) as all Ducati are geared for top speed and improved fuel economy. BTW, my 1260 Multistrada has this Tire Calibration feature. I've toyed around with it a few times at different speed within the range in an attempt to see if I could reduce the speedometer's tracking error. For it to work, speed must be held within the range for 5 sec. BTW, I could not reduce the speedo's (dream-o-meter) tracking error which overstates the display velocity by 5~8% depending on the model.
The owners manual actually states that the speedo over reads by 6% IIRC. Most vehicles do. It's because the law states that they can read up to 10% over speed but never under speed. So I guess the manufacturers aim for the middle of the allowed range of error.
