Ducati.ms - The Ultimate Ducati Forum banner
  • Hey Everyone! Enter your bike HERE to be a part of this months Bike of the Month Challenge!

1 - 20 of 35 Posts

·
Registered
Joined
·
102 Posts
Discussion Starter · #1 · (Edited)
When you buy a used bike, things are always a surprise. 15/42s on the ST4S, replaced with 15/43s. Slight improvement on takeoff, but not much. Anything is better than nothing.

Ran it around the block. Will put a couple more miles on it and readjust the chain for the initial slack. Was a bit worried there for a bit that the chain would be too short, but it seems fine. Slightly loose after my spin. Feeling a bit relieved. Funny how all that stuff comes back to you after nearly 30 years.

Found a 45 tooth for next time around, but gotta wear this one out first.
 

·
Just Visiting Your Planet
Joined
·
10,253 Posts
You want a 15-45 combo? :confused:

What are your roads like out there? Plus, that's exactly a 1:3 sprocket ratio which isn't good for wear. The teeth will always hit in the same spots over and over.
 

·
Registered
Joined
·
102 Posts
Discussion Starter · #3 ·
[/U]
You want a 15-45 combo? :confused:

What are your roads like out there? Plus, that's exactly a 1:3 sprocket ratio which isn't good for wear. The teeth will always hit in the same spots over and over.
The things we forget after all these years. Thanks. Might have to experiment with a 14T in the front. The goal is more usable gear ratios for around town and tighter corners.
 

·
Premium Member
Joined
·
573 Posts
think that (14/43) is what most of us use.. i know i do. did help a lot.
 

·
Premium Member
Joined
·
5,656 Posts
OEM on the ST4s is 15-38. With OEM gearing, you need to be going around 90 to use 6th without lugging the engine.

I ran a 15-43 on my ST when I lived in VA. It was fine for that area. Speed limits were lower and more strictly enforced than up here in CT where everyone is is doing at least 80 regardless of the posted limit. When I moved to CT, I found it too low and moved to 15-41. I find 15-41 perfect for the area roads and general flow-of-traffic speeds on the highway.

Gearing for a street bike is not about top speed. You should be looking for that ratio that does the best job of keeping the engine in its RPM sweet spot for the conditions you rind in and the speeds you travel.

For Ducati in general, at least the older ones like our STs, up three on the rear or down one on the front set the bike up pretty well.

The much linked gearing commander.
https://www.gearingcommander.com/

plug in the appropriate bike data, load the ratios you want to try and see the speed / RPM combos...
 
  • Like
Reactions: spikey1973

·
Premium Member
Joined
·
573 Posts
how would one obtain the "appropriate bike data"?
 

·
Premium Member
Joined
·
5,656 Posts
how would one obtain the "appropriate bike data"?
Look at your bike:grin2:

It asks for make model and year. You plug that in to the appropriate fields on the spread sheet and it gives you the correct ratios for all gears and also loads tire size (and diameter) for you specific bike. That is used to proved the most accurate results of RPM vs Speed for a given final drive ratio.
 
  • Like
Reactions: spikey1973

·
Registered
Joined
·
456 Posts
My sprocket change was from 15/42 to 14/43 on my 98 ST2. Absolutely love it. Gave me 700 rpm more in each gear which keeps the engine in an appropriate spot vs lugging the motor/clutch. I got 45 mpg in steady state touring all loaded up and 37-40 unloaded in the mountains at the ECM a couple weeks ago.


2002 Yamaha FZ1
1998 Ducati ST2 apocalypse edition
 

·
Still needs a life.
Joined
·
12,619 Posts
I ran 15/42 on both of my ST4s bikes. It kept the RPM's in the sweet spot of 3,000-3,500 at street and highway legal speeds plus made starting up a hill after stop easier.

It should also be noted that the ST4s engine is not fully broken it until 10,000 miles and runs much smoother after that.
 

·
Premium Member
Joined
·
573 Posts
3000-3500 is your sweet spot? i'd say my sweet spot (ST3 and ST4) was right after 4000 RPM, well that is at least my experience.
 

·
comrade moderator
Joined
·
27,182 Posts
I currently have 15/42 on my '05 ST4S. I tried a 14 but it was way too low.
Now I'm due for chain & sprocket replacement and still have this new 14 so I'll go with a 40 rear to lower the gearing just a smidge from the 15/42 ratio.
 

·
Registered
Joined
·
102 Posts
Discussion Starter · #12 ·
3000-3500 is your sweet spot? i'd say my sweet spot (ST3 and ST4) was right after 4000 RPM, well that is at least my experience.
Below 3500-4000 mine bucks and generally is not very happy.
 

·
Retired Pipe Polisher C2H6O+
Joined
·
19,081 Posts
My new chains always get a bath in a pan of diesel and wiped clean before mounting them.
 

·
Retired Pipe Polisher C2H6O+
Joined
·
19,081 Posts
Nope. My current chain has 25000 miles on it. Several times a year it gets brushed with diesel and rinsed off. Like after a long road trip.




Sent from my iPhone using Tapatalk Pro
 

·
Premium Member
Joined
·
5,656 Posts
My new chains always get a bath in a pan of diesel and wiped clean before mounting them.
Yup, but I use Kerosene.

diesel won't affect the orings?
Nope. Better than WD40 which is said to possibly hurt them if you use the spay can version. Something in the propellant, but I may have that wrong. I've used WD40 too and have had no problems. If it effects the o rings, it doesn't cause a problem before the chain is worn out anyway, or at least that's been my experience.

First I've heard of ThreeD chains. Look interesting, going to have a look!
 
  • Like
Reactions: bloodycrashboy
1 - 20 of 35 Posts
Top