I am in the middle of a gear change on my 1098,I didnt like the stock gearing nor did I like the 14 front sprocket,so i got a chain and sprocket kit w/15/40 and a 100 link chain,put it all together(didnt press the pins yet)and turned the eccentric to see if the chain length was ok,well it wasnt the eccentric turned then stopped I could no longer rotate it and the chain was still way to loose,I should have stopped there but stupid me goes and presses out a link shortening the new chain to 98 links,I can get the chain to adjust now but tire is really close to the swing arm like 7mm.
So my questions to anybody out there that knows;
1)was I being to careful(read puss) in turning the eccentric or is there a stop of some sort?
2)98 links is just right and thats how close the tire is to the swing arm and I am just freaking out?
Your tire should have moved back 4mm when you went from 15/38 96-links to 15/40 98-links. If you miscounted and you still have 96-links it will have moved your tire forward 8mm from the stock setting.
My guess is that your eccentric is incorrectly positioned above the axis centerline.
Look at the swingarm from the left side of the bike. Behind the rear sprocket is a hole in the swingarm. In this hole is the eccentric which is a piece of metal with a hole in it for the axle. The axle hole is not in the center of the eccentric but off to one side. When you rotate the eccentric the axle hole moves like the hour hand on a clock (around the center of the eccentric.) The idea being that when the axle hole is at the 3 o'clock position it puts the most tension in the chain and at 9 o'clock the least. The word eccentric (opposite of concentric) meaning two things not having the same center.
The eccentric hub should nominally position the axle between the 4 and 5 o'clock position (viewed from the left side). Be careful, you can also obtain the proper chain tension when the eccentric is in the wrong position - with the axle set between the 1 and 2 o'clock position. If it is set higher than the 3 o'clock midpoint, there will be inadequate clearance between the lower run of the chain and the swingarm and the rear ride height will be too low. You'll also have inadequate clearance between your swingarm, rear tire and hugger (it'll rub) if you have one installed. If you get to the 3 o'clock position and the chain is still too loose, you'll need to remove at least two chain links and retry.
What I don't understand is why 1098 owners are changing their gearing. For more than a decade, owners of 916's, 916SPS's, 996R's 996SPS's, 998's, 998R's, and 999's have switched to a street optimum of 15/38 ... but when Ducati finally builds a bike with proper gearing, the 1098 owners are changing it. Why? (Rant over)
My stock chain has 98 links,Thank you for the around the clock explanation,I will look at this.
As far as gearing goes the 15/38 on the 1098 its so freaking hard to ride in traffic,anything below 20mph has you feathering the clutch like crazy to keep the bike from chugging you off it and it never seems like your in the right gear.
The internal transmission ratios must be different from the older bikes or the torque pules's from the bigger engine are that much more pronounced
I just went and looked at it and my axle is at like 5:30,I think there must be some sort of stop in there to prevent it rotating past the 3:00 midpoint.
I am counting total number of pins in the chain(this is correct right?),my stock chain has 98,the new chain had 100 and was too long.
To anybody else out there w/a 1098 and a 15/40 gearing what length is your chain?
So, if you still have 98-links with two additional teeth on the rear sprocket, the tire has moved forward 8mm which is causing the tire-swingarm clearance problem.
And, since you're at the 5:30 eccentric position now then the 100 link chain would have put you at 3:00,with too much slack and without further adjustment for chain stretch later. (Each link is 16mm long, each tooth takes 4mm.)
The difference between 14/38 and 15/40 is quite small, 2.71:1 vs 2.67:1 respectively. So around town the 14/38 is more of an improvement.
The problem with eccentric adjusters is that you can't control each variable independently. For example, when you change the eccentric clock position you change not only the wheelbase but you also change the rear ride height that in turn affects handling.
The bike comes with the rear ride height adjustment rod at its shortest length so if you use a rear sprocket with one, two or three more teeth you shorten the wheelbase 4mm for each tooth and raise the rear ride height similar amounts. If you add four teeth you then add two links to the chain, and your wheelbase and ride height is back where you started.
(You did measure the rear ride height before you started so you could reset it after the sprocket change, right?
Under the circumstances I'd go back and try to live with the 14/38 setup. You didn't say why you didn't like this ratio but if it's because you wanted something even lower for around town then 14/40 (2.86:1) is better still and will solve your clearance issue.
No I did not measure the ride height,this being my first single sided swing arm bike that fact of ride height and wheelbase is not in my head yet,but it is now.
the 14/38 was too low for the highway 80mph was around 5k and put the eccentric past the 4:00 position,I am going to call the place I got the kit from and see if he will exchange the 40 for a 39
well I marked the eccentric with it all together and took it back apart to see exactly what position the hub was in it turns out it was in the 6:00 position
so a 15/40 gear will not work w/the 1098,with a 98 link chain its at 6 and w/a 100 link chain its too loose way past 4.
With it currently 7mm away from your swingarm it's not rubbing on anything correct? if thats the case, your chain will stretch as it's new and needs to wear in. After a hundred miles or so check the slack and chances are very likely you'll need to tighten it up. As long as it's not rubbing on anything I would ride it and check it again in a few weeks.
heres a some pics,the one from the side is where the axle was positioned w/the 40t installed you can clearly see its way off time,the other are marks on the eccentric to show how far off it was,the marks that are aligned are w/the 40t the other marks at top and bottom align w/38t
the 7mm distance I mentioned was a guesstimate using a section of vacuum hose and rolling the tire around,there was resistance and the hose was 8mm so I figured 7mm but it may have been even less.
I could have ridden it and let the chain loosen then readjusted,but I didnt feel that comfortable in doing that.
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