Choosing the perfect sprockets for your Ducati Scrambler
I ride a 2016 Scrambler Ducati Icon, and I think we can all agree, within the city, it is amazing - light, nimble, and torquey, but when I take it to the highways and reach around 80 mph, I find myself reaching for the non-existent '7th gear.' Why is that?
The stock gearing for the Scrambler 800s, Desert Sled, and Cafe Racer prioritizes the lower gears to take on some dirt riding. The stock set up for the front and rear sprocket is 15 and 46 respectively, giving a ratio of ~3.07 (rear sprocket (46) divided by front sprocket (15) gives you the ratio). Without going into crazy detail, a gearing ratio lower than 3.07 would mean higher top-speed and less torque than stock, and a gearing ratio higher than 3.07 would mean a lower top-speed and more torque than stock.
Note: we have not explored the optimal gearing for the Scrambler 62 (15 and 48t) or the 1100 (15 and 39t) yet, but the same principals apply!
So what should I prioritize?
For me, and many other Scrambler riders and racers (Heath 'The Chief' Cofran & Jerrett Martin), the need is more a higher top speed. We feel that the engine RPM is too high at cruising highway speeds thus causing excessive strain on the engine. We all complain about the same thing, but none of us want to lose that fun torquey quality, how do we fix that? Find the balance. In this case we will have to give up some grunt for easier top speed. Again our baseline comparator is the stock set up - 15t front sprocket and 46t rear sprocket, and there are two options we explored.
Option 1 (16 teeth front sprocket, stock 46 teeth rear sprocket): 2.88 gear ratio
The positive side of changing front sprocket to 16 teeth is less overall wear on the engine, front sprocket and chain, higher top speed, and it is cost effective - a front sprocket costs 20 to 30 dollars!
It is important to note that your sprockets wear down at the same rate, so it is always optimal to change your chain, front, and rear sprockets out together. But if you have a fresh chain and little miles on your rear sprocket, it is the most cost effective to simply switch out your front sprocket. This way, you can test out this gearing and see if a lower ratio is for you!
Another important note, because there is limited clearance at the front sprocket position, and the front sprocket would be changed to a larger tooth (from 15t to 16t) some people report that they had issues fitting the front due to inadequate spacing between the chain and the engine casing. Clearance issues may vary on your particular bike due to manufacturing variability. Some (not all) riders have reported having to file metal to make the chain fit a 16 teeth sprocket.
Option 2 (stock 15 teeth front sprocket, 44 teeth rear sprocket): 2.93 Gear ratio
Change the rear to a 44 teeth sprocket and get a new chain with 2 LESS LINKS THAN STOCK (super important if the bold letters didn't indicate that already). Why do you need two less links? Taking 2 teeth outmeans the axle adjustment will have to slide much farther back thus changing the wheelbase of the bike and suspension geometry. Worse case scenario is you will run out of adjustment and the chain won't work anyway. So get a new chain with two less links than factory!
Astroscrambler top tip: Get a complete chain and sprocket kit consisting of a 15t front sprocket, 44t rear sprocket, and a chain with 2 less links than stock. Front sprockets generally wear out faster since they are smaller so you might as well replace it when changing the gearing ratio. Rule of thumb is also to change the chain when replacing any sprockets thus allowing the new sprocket to seat the mating surfaces to a new chain thus preventing premature wear from a stretched used chain. So get the kit and you won't need to worry about chain and sprocket maintenance for awhile!
Should I change my gearing?
If you do mainly city commuting and don't mind the stock gear ratio, then don't worry about it. However, if you ride a decent amount on the highway, want better MPG and less wear on the engine, or just hate shifting too often then we recommend changing the gearing. It's a relatively cheap upgrade to do that you can time with your next interval chain and sprocket replacement.
How should I choose my chain?
Your Scrambler is powered by chain drive, meaning the power that comes from the engine passes through your chain. We recommend a high-strength aftermarket chain from top brands such as ER, RK and DID. High quality chains are optimally rigid, giving you smoother handling, power loss reduction, and a quicker response compared to stock. Most importantly, if properly maintained it will LAST 8-10k miles! Stay tuned for our next article on different chain types!
Summary - OEM sprockets 15t front and 46t rear.
Option #1 16t front sprocket (+1) and 46t rear sprocket (no change) = 2.88.
Advantages
- Cost - only need to change front sprocket and can test out new gearing IF rear sprocket and chain still relatively new.
- The front sprocket is larger and some people have had to file down to ensure fitment.
- It is optimal to replace front and rear sprocket at the same time because they wear at a similar rate.
Option #2 15t front sprocket (no change) and 44t rear sprocket (-2) = 2.93
Advantages
- Would typically be replacing chain and front sprocket with rear sprocket, making a huge upgrade from stock pieces.
- Optimal top-end speed while maintaining fun torque
Disadvantages
- Cost - because you're decreasing the teeth in the rear by 2, it's optimal to get a chain upgrade, BUT if you are due for a replacement it's the perfect time to do this change.
What do you think? Which gearing ratios have you tried? Has anyone opted to go higher than 3.07? We have heard some feedback on the Desert Sled riders that they wanted more low-end power.