Chain and sprocket question

**Stylo** · 3rd August 2015, 18:11

Just put a new O-ring chain and steel sprockets on my dirtbike and decided to gear it down a little, going from a 47 to a 49 rear. Reason for doing this is I don't need top speed so much as the riding I'm doing ( or about to do as I've been out of the loop for a while ) is generally involving a lot of slower stuff/technical rather than top speed. I haven't had it out for a ride yet but was wondering this ...

If, after the first 30 or so minutes I decide the shorter gearing is too low, how stretched would the new RK chain be on that first squirt if I decided to swap back to a 47 on the back and kept using the ' newish ' chain ? , cheers ..

**FJRider** · 3rd August 2015, 18:29

The chain will be fine ... just get a bigger bike ...

**mossy1200** · 3rd August 2015, 18:33

If the only thing you changed is up 2 teeth on rear then its 4% lower gearing. Surprised you even notice a lot of difference.

**husaberg** · 3rd August 2015, 18:53

Originally Posted by Stylo

Just put a new O-ring chain and steel sprockets on my dirtbike and decided to gear it down a little, going from a 47 to a 49 rear. Reason for doing this is I don't need top speed so much as the riding I'm doing ( or about to do as I've been out of the loop for a while ) is generally involving a lot of slower stuff/technical rather than top speed. I haven't had it out for a ride yet but was wondering this ...

If, after the first 30 or so minutes I decide the shorter gearing is too low, how stretched would the new RK chain be on that first squirt if I decided to swap back to a 47 on the back and kept using the ' newish ' chain ? Bike is a KX500, cheers ..

Just add a tooth on the front or buy a new rear

**caspernz** · 4th August 2015, 04:01

Originally Posted by Stylo

Just put a new O-ring chain and steel sprockets on my dirtbike and decided to gear it down a little, going from a 47 to a 49 rear. Reason for doing this is I don't need top speed so much as the riding I'm doing ( or about to do as I've been out of the loop for a while ) is generally involving a lot of slower stuff/technical rather than top speed. I haven't had it out for a ride yet but was wondering this ...

If, after the first 30 or so minutes I decide the shorter gearing is too low, how stretched would the new RK chain be on that first squirt if I decided to swap back to a 47 on the back and kept using the ' newish ' chain ? Bike is a KX500, cheers ..

Half an hour on a dirt bike won't stretch a chain, and like Mossy already commented adding a couple of teeth on the rear won't make a big difference. Drop one off the front sprocket however...

The gearing commander website is handy. http://www.gearingcommander.com/

**Drew** · 4th August 2015, 07:44

Originally Posted by mossy1200

If the only thing you changed is up 2 teeth on rear then its 4% lower gearing. Surprised you even notice a lot of difference.

Is it? I think it's 4% different on the rear, but because of there being an existing ratio between front and rear sprockets, that 4% is magnified by that same factor.

Or am I over thinking this.

**caspernz** · 4th August 2015, 18:37

Originally Posted by Drew

Is it? I think it's 4% different on the rear, but because of there being an existing ratio between front and rear sprockets, that 4% is magnified by that same factor.

Or am I over thinking this.

This round goes to Mossy, as it's actually a 4.27% drop in gearing. Something like stock at 50 km/h would be 6470 rpm, whereas 14/49 would bring 6746 rpm, so mr gearing commando says anyhoo.

**mossy1200** · 4th August 2015, 22:59

Originally Posted by caspernz

This round goes to Mossy, as it's actually a 4.27% drop in gearing. Something like stock at 50 km/h would be 6470 rpm, whereas 14/49 would bring 6746 rpm, so mr gearing commando says anyhoo.

I just went 47 to 49 on rear is approx 4% change. I just don't see that being very noticeable on the dirt especially if the op wanted to gear the bike down a bit.
Maybe the extra acceleration is making it feel like its reving out easily or the op has got better at riding and its now a bit slower than he remembers.
If op dropped a tooth on the front sprocket unknown and added 2 onto rear also then the difference would be quite large.

**granstar** · 3rd September 2015, 21:29

Originally Posted by husaberg

Just add a tooth on the front or buy a new rear

Just changed the front 16T to a 17T on my 900 Hornet, yeah I know not a trail bike ( but it could be) bit of a difference in a good way. Has taken a little sting out of it's tail but made it a really good open road cruiser and is much smoother ride through the gears, a worthy mods if you are not into pulling wheelies, hasn't lost any grunt maybe a little top end, speed limit is 100

.

**husaberg** · 3rd September 2015, 21:33

Originally Posted by granstar

Just changed the front 16T to a 17T on my 900 Hornet, yeah I know not a trail bike ( but it could be) bit of a difference in a good way. Has taken a little sting out of it's tail but made it a really good open road cruiser and is much smoother ride through the gears, a worthy mods if you are not into pulling wheelies, hasn't lost any grunt maybe a little top end, speed limit is 100

.

cheap and easy too.........

**Drew** · 4th September 2015, 06:28

Originally Posted by granstar

Just changed the front 16T to a 17T on my 900 Hornet, yeah I know not a trail bike ( but it could be) bit of a difference in a good way. Has taken a little sting out of it's tail but made it a really good open road cruiser and is much smoother ride through the gears, a worthy mods if you are not into pulling wheelies, hasn't lost any grunt maybe a little top end, speed limit is 100

.

It won't effect the wheelies. Hornet is well grunty enough to hoist when geared up a bit.