Sprockets

[Timmy6216]

15/45 is the same ratio as 13/39 so... the 13T experience?

so with it being bigger sprockets across both, the RPMs are un changed?

my mind is not grasping how a 13/39 and a 15/45 while same ratio have the same RPM.

 

[m in sc]

i misread, i thought he asked about 13/45. lol.

13/39 vs 15/45 will make absolutely zero difference in how the bike behaves to each other. the 15/45 is easier on the chain as the front sprocket isn't making as tight a turn

both turn the rear wheel .333 per 1 revolution of the front sprocket. so, the same.

 

[ShieldArc]

Chain might last longer with a bigger front sprocket.

 

[SneakyDingo]

The idea with the larger cogs front and back is, in general, that the load will be spread over a large number of teeth and they will last longer, so yeah, theoretically things will last longer. In practice, the difference isn't really that much, you're better off doing better quality maintenance, etc.

 

[dmonkey]

More mass (bigger sprockets, longer chain) = more inertia. Probably negligible, but in theory it could make it less "snappy". Whether or not that would be desirable is up to your preference.

 

[SLO]

So a question for my 15/45 geared folks...what does the make the bike feel like? if you had to run on pavement is the motor screaming to get out of its own way, like pegged rpm? is it just snappier off the line? My wandering of the internets will tell me all about each gear and what the finial ratio is, but im trying to see if the bike gets more or less buzzy on the top end ect from other riders.

I don't need sleep, I need answers

If you want to ride 45 mph plus,you are going to have rev the shit out of it. It will outlast you,unless you expect to put 50k miles on it. Use the Castrol JASO 4T synthetic blend. Most of the engine wear occurs in the first 20 minutes when new. Ride it,worry about other shit!

 

[m in sc]

it has to do with the angle of turn to reduce chain wear. the 'rounder' a chain path is, the longer it will last.

 

[ShieldArc]

it has to do with the angle of turn to reduce chain wear. the 'rounder' a chain path is, the longer it will last.

Ding ding we have a winner.

 

[SneakyDingo]

it has to do with the angle of turn to reduce chain wear. the 'rounder' a chain path is, the longer it will last.

Fun note on this: the same theory was floated by the Schleck brothers for the Tour de France as well, oversized rollers on their derailleurs to reduce friction. Considering the Schlecks did pretty well (Andy Schleck won the 2010 TdF), SRAM and Shimano ran with the idea for testing and didn't find any appreciable difference. Sounded a bit like carrots and night vision, but it would have been cool to get real numbers.

 

[m in sc]

has nothing to do with friction of the roller, its the bend angle of the links on the front sprocket, you completely missed the point.

 

[Claude Newton]

C

Put on Shinko 3/0 244s. It will correct speedo,as well as ABS light

Are the Shinko 3.0 244's on rear only or on front too.

 

[AZ7000']

Most use them on both, i would go so far as to say that is the standard

 

[SLO]

Are the Shinko 3.0 244's on rear only or on front too.

You gotta raise front fender. It only requires drilling a couple holes to move it up,no aftermarket gizmo needed. I feel much safer on them,as road conditions vary,but even on the twisty RT.58 from Damascus up the mountain. All new tires require braking in,as I discovered going up to Hayter's Gap from Elk Garden. Ass end slipped a little going uphill while leaning. You have to break in all parts of tire,even parts that don't normally hit the pavement.

 

[Timmy6216]

Hi ya folks! so I did the 15/45 and I love the difference. my Speedo is a few miles fast and I don't mind. GPS has me at 53mph top speed (56 indicated) . I'm not mad at that. It runs and sounds good and not even super buzzy (to me)
I also added a new HD chain.
I love my trail.
I am one of the nicest people you'll meet on a Honda lol

 

[SLO]

Hi ya folks! so I did the 15/45 and I love the difference. my Speedo is a few miles fast and I don't mind. GPS has me at 53mph top speed (56 indicated) . I'm not mad at that. It runs and sounds good and not even super buzzy (to me)
I also added a new HD chain.
I love my trail.
I am one of the nicest people you'll meet on a Honda lol

GPS does not indicate ground speed,but nautical miles per hour. Curvature of the earth make a difference,depending on type of GPS,it may be accurate,which would indicate slower than ground speed.

 

[Timmy6216]

GPS does not indicate ground speed,but nautical miles per hour. Curvature of the earth make a difference,depending on type of GPS,it may be accurate,which would indicate slower than ground speed.

Well it said I was not going as fast as my speedo. and it had 29 satellites of 30 I think. Either way, still a fun ride!

 

[oldskool]

GPS does not indicate ground speed,but nautical miles per hour. Curvature of the earth make a difference,depending on type of GPS,it may be accurate,which would indicate slower than ground speed.

Are you sure? When my speedo says 55 my GPS says 52. So if that is 52 NPH that means my CT goes just under 60 MPH As nice as that would be it ain't true. Not all GPS indicate speed in knots, the Garmen is either you can change it.

 

[dmonkey]

GPS does not indicate ground speed,but nautical miles per hour. Curvature of the earth make a difference,depending on type of GPS,it may be accurate,which would indicate slower than ground speed.

I'd trust the speedometer (with OEM tires and gearing) to give a more accurate read at low speed, GPS for a more accurate read when you're looking at top speed. You could certainly dial in the speedometer to be more accurate with a speedo healer or an aftermarket unit though.

Smartphones and dedicated navigation devices like a Garmin, TomTom, or even bicycle computers can account for curvature of the earth as well as elevation change for displaying speed. Surface mapping (2D) is different, but GPS signals provide data for 3D mapping and many newer consumer devices make use of it. Still not perfectly accurate. They GPS is not showing you nautical miles per hour unless you've got it set to, and it's not going to disguise nautical miles per hour as miles per hour since those are different units of speed.

GPS pitfalls are largely signal blockage, signal reflection around tall buildings, changes in speed or direction that occur in a short time or distance that the few meters range of accuracy isn't precise enough to account for when averaged out, and bad data from satellites often related to space weather events. Some of those issues can be partially compensated for on phones by using more sensor data (magnetometer, gyroscope, or accelerometer), A-GPS which uses cell towers to quickly and more accurately pick up on the device's location, or Wi-Fi positioning system which uses known WiFi network locations to get a rough idea of where the device is when there isn't an open sky for GPS or enough towers for A-GPS. IMO those features add privacy concerns, but not much different than carrying your phone along with WiFi and cellular enabled.

The CT125's speedometer reading is also an indirect measurement of ground speed. It's measuring rotation at the countershaft with no regard for chain and sprocket wear, variances in tire circumference from tread wear, load or pressure, or where contact is being made on the tire. I don't think Honda dialed it in to be very accurate when stock and new either, but instead targeted a percentage variance that doesn't under report the speed while accounting for what some average of those other variables might work out to be.

@vintagegarage put together a video comparing speedometer readings to GPS readings. If I caught highest speeds right, the speedometer hits a maximum of 57 mph while the GPS hits a maximum of 55 mph in the clip.

The difference in mph scales, so mph difference at low speed isn't very observable, mph difference at high speed is more observable while only useful given the context of that speed. A percentage scales, though basing a percentage on an imprecise unit of measure (mph in whole numbers, made as precise as we can by using the top speeds) results in a percentage that may not be very precise or accurate. Can still work that out for a rough number though.

Difference: 57 mph - 55 mph = 2 mph
Average of the two speeds: (55 mph + 57 mph) / 2 = 56 mph
Percentage difference: (2 mph / 56 mph) x 100% = 3.57%

 

[hambone]

My stock bike reads 40mph on speedo and 39 on gps, my son's bike with 13/42 gearing and golden boy tires reads 40mph on speedo and 33 on gps.

 

[SLO]

I'd trust the speedometer (with OEM tires and gearing) to give a more accurate read at low speed, GPS for a more accurate read when you're looking at top speed. You could certainly dial in the speedometer to be more accurate with a speedo healer or an aftermarket unit though.

Smartphones and dedicated navigation devices like a Garmin, TomTom, or even bicycle computers can account for curvature of the earth as well as elevation change for displaying speed. Surface mapping (2D) is different, but GPS signals provide data for 3D mapping and many newer consumer devices make use of it. Still not perfectly accurate. They GPS is not showing you nautical miles per hour unless you've got it set to, and it's not going to disguise nautical miles per hour as miles per hour since those are different units of speed.

GPS pitfalls are largely signal blockage, signal reflection around tall buildings, changes in speed or direction that occur in a short time or distance that the few meters range of accuracy isn't precise enough to account for when averaged out, and bad data from satellites often related to space weather events. Some of those issues can be partially compensated for on phones by using more sensor data (magnetometer, gyroscope, or accelerometer), A-GPS which uses cell towers to quickly and more accurately pick up on the device's location, or Wi-Fi positioning system which uses known WiFi network locations to get a rough idea of where the device is when there isn't an open sky for GPS or enough towers for A-GPS. IMO those features add privacy concerns, but not much different than carrying your phone along with WiFi and cellular enabled.

The CT125's speedometer reading is also an indirect measurement of ground speed. It's measuring rotation at the countershaft with no regard for chain and sprocket wear, variances in tire circumference from tread wear, load or pressure, or where contact is being made on the tire. I don't think Honda dialed it in to be very accurate when stock and new either, but instead targeted a percentage variance that doesn't under report the speed while accounting for what some average of those other variables might work out to be.

@vintagegarage put together a video comparing speedometer readings to GPS readings. If I caught highest speeds right, the speedometer hits a maximum of 57 mph while the GPS hits a maximum of 55 mph in the clip.

The difference in mph scales, so mph difference at low speed isn't very observable, mph difference at high speed is more observable while only useful given the context of that speed. A percentage scales, though basing a percentage on an imprecise unit of measure (mph in whole numbers, made as precise as we can by using the top speeds) results in a percentage that may not be very precise or accurate. Can still work that out for a rough number though.

Difference: 57 mph - 55 mph = 2 mph
Average of the two speeds: (55 mph + 57 mph) / 2 = 56 mph
Percentage difference: (2 mph / 56 mph) x 100% = 3.57%

Watch out! WAtch the road! Evel Kneivel did not have a speedometer on his bikes because it would give him a reason to look down,not at the road. Mod it,ride it. Maybe it is where I live,but I could outrun myself on the Red Rocket vs my KTM 390 ADV , or my DR 200.