MR Motorcycles Waeranga Ride

[IIIRII]

Ok so you cant edit your own post, shot kiwibiker...
So what Im saying is Im not disputing the cost difference, but I am saying theres a huge difference in
the various effects from altering ratios.
A smaller front will make it a lot snappier in wet or slow stuff and it will make it a lot more prone to wanting to lift the front.

[oldskool]

Na Crisis, I was commenting on Oldschools Ktm 350. Your correct about Greenmachine. There are two guys doin opposite things. LOL!! I haven't ridden Oldschools bike but I think for him going down in the front will make it much more of a handful on the muddy climbs, after riding with him last sunday.
!

Jeez theres a lot of overthinking goin on here! That slippery hill caught me out because I had to stop 1/3 of the way up because a rider had broadsided across my path. In retrospect if I had slid back down to the bottom and taken it again it would have been much easier than trying to attempt it again from where I had stopped. Momentum was the key there. The next loop around without a traffic jam it was an easy climb.
In tight stuff the bike does seem to feel it needs to be revving higher than it is, because it tends to lug a lot (uh oh here we go, open up the fan the clutch debate). Anyway moot point I prefer a bike that wants to pop the front wheel and this one does feel a bit *tame (*edit* heavy on the front wheel). Good to hear it can with a minor change of gearing.

[Crisis management]

Good to hear it can with a minor change of gearing.

Gearing is a huge difference, one in the front transforms a bike and you should try it, it's cheap and educational (not taking the piss). At the end of the day you need a bike that provides traction & power as you like to use it and the only way to find out is to try it. Go for it.

[oldskool]

I found dropping a front tooth on my old KX125 made it climb hills easier, I could control the front wheel over logs better and it hit the pipe quicker. Before that the thing was a dog.
With my sons RM, with a larger front sprocket it had no torque, when you revved the crap outa it to go forward, there was nothing then came the wheelie. Losing a tooth in the front and it is easier to start off and climbs hills a lot easier without the fear of a wheelie. So theres the other spectrum to the debate. Hmm I wonder why trials bikes are so tame (controllable)?

[Reckless]

Jeez theres a lot of overthinking goin on here! That slippery hill caught me out because I had to stop 1/3 of the way up because a rider had broadsided across my path.

Sorry Oldshool I wasn't pointing to any one event, or critising your riding, that hill was a mess with other riders everywhere and I could have very very easliy been in the same boat. Sometimes its luck of the draw on those rides, my opinions where an overall observation. And yes you may be correct in my overthinking this issue as I didn't ride your bike. It's just that it seemed to already deliver really good power, in fact when I was following you you roosted me heaps without even trying to (or where you LOL!!) and I think that going to a 13 front may be the wrong move.

Anyway moot point I prefer a bike that wants to pop the front wheel and this one does feel a bit tame. Good to hear it can with a minor change of gearing.

Yep if thats the way you prefer the bike you should try it and agreed its only a front sprocket you easily can take off if you want to go back!
Can I ride it with the 14 on first though?? LOL!!!

Sorry mate if anything I said could have been taken the wrong way.
Cheers!

[husky]

Yeah mate you did help me,i had a crack at the left hand crossing and stalled the Green Beast ,they are heavy when your shagged,you were having a sit down and came to my rescue....cheers for that,and as you saw,none of the 5 guys i came with were anywhere to be seen,haha

Devo we were all back in the carpark by then!!

[oldskool]

Sorry mate if anything I said could have been taken the wrong way.
Cheers!

haha no I wasn't getting too prickly...was I?...haha. No seriously the bike is cool for open hill riding, try it out at the sandpit, like say The Finisher, and you'll be thinkin twice about the gearing. Plenty of bottom end and tall gearing makes for plenty of rear wheel rotation at low revs. I don't think reducing a tooth up front is going to turn it into a firebreathing 2T beasty, it has quite a broad tame powerband, and I ain't gonna be flipping it left right and centre because of it.
There was a bit of confusion goin on with greenies KXF450 which IS a fire breathing 4T MX and my very rider friendly 4T Enduro.

No offense taken mon!

[Reckless]

haha no I wasn't getting too prickly...was I?...haha. No offense taken mon!

Na mate but I just wanted to make it clear as the written word is easily misconstrued? (is that a word?) LOL!

[Ride it till the red]

Ok lets assume we want more top speed
The current ratio between the output shaft and the rear wheel is 14 48 so 48/14 = 3.42 :1
Lets assume this gives 100kph @ 8000 rpm.
You want more top speed you need a lower ratio maybe 15 48 so 48 /15 = 3.2:1 which will give about 5% more top end.
When you lower the top speed by raising the final ratio 13/48 3.7:1 theres more than one way of doinf this .
You can run 13/48 or 14/52 or 15/56 or being sill but still demonstrating what i mean 25/92 these all give the same TOP speed @ the same given RPM.
But like I said before, the way the engine can deliver the power (torque) to the wheel is very different , if you think of the sprocket being a lever , the engine will move the lever with a lot less effort the shorter it is. (smaller radius sprocket) therefore it will initiall move the bike much more reactivley than with a longer lever and it will be more controlable and more progressive.

But the engine isn't pushing on a lever it's turning the countershaft.....
And whatever combination of sprockets you use the resistance to the countershaft will be the same at the same final drive ratio, as you've shown above indicated with top speed.....
I can't see how acheiving the ratio differently would make any difference myself (apart from increased chain wear with smaller front sprockets), despite googling to try and find something to support your theory.

I'll be going 1 tooth up on the front next week in search of more top speed, I'd say my bike should have enough power that the loss isn't an issue but if it is maybe I'll try doing it your way just as an experiment

[krad_nz]

Interesting thread guys.

RITTR I think you and IIIRII are both saying the same thing differently. If the gearing is the same, then is the load on the countershaft the same too? I'd say yes.

If I add an extra tooth on the front sprocket then I'm pushing more chain around per rotation. The chain connects to our load, the rear wheel as we all know. If the chain is now moving faster than standard due to an extra tooth on the front then we're presenting more load to the motor for a given RPM compared to the standard ratio's at the same RPM. So basically the rear wheel turns further for the same RPM. This is all good assuming the motor has the torque to pull it off.

If you then increase the # of teeth on the rear sprocket too, effectively reducing the load, then you are back where you started. Of course you now have a longer chain and bigger sprockets which means more rotating mass etc.

[oldskool]

Interesting thread guys.

RITTR I think you and IIIRII are both saying the same thing differently. If the gearing is the same, then is the load on the countershaft the same too? I'd say yes.

Well what I am visualising after reading Glenns analogy is if you had an imaginary lever running on a tangent off the rear sprocket and an imaginary lever running on a tangent off the front sprocket and you use your finger to push one or the other and according to Glenn there is a difference. From what I gather he is saying the rear sprocket lever would have more finesse and control turning the 18" rear wheel than if you pushed the imaginary lever on the front sprocket to turn the same 18" wheel. What I have difficulty in accepting is the rear wheel is firmly attached to the rear sprocket and is still 18" in diameter.

[D dub]

Na Crisis, I was commenting on Old Schools Ktm 350. Your correct about Green Machine. There are two guys doing opposite things. LOL!! I haven't ridden Old Schools bike but I think for him going down in the front will make it much more of a handful on the muddy climbs, after riding with him last sunday.
He's after more grunt to overtake my little 2hundy LOL!! I should keep quiet and let him do it but fairs fair!

Just my 2c though even if he tries it its only a front sprocket LOL!!

PS I added a quote to clear up the confusion Sorry mate!

I used to have one of these and they are not to be confused with the twin over head cam motors in the modern 250 four strokes, they are very tame and need the lower gearing to bring them to life! I use to run 13/52 with good results and zero negative effects!!!
Other than having to change gear a bit moor often but it made the bike a lot easier to ride in all conditions!!!

[IIIRII]

Its called a mechanical advantage,
Ill try one more analogy
Option 1 I have an electric motor with a 50mm pulley on it and a benchsaw which has lets say 200mm diameter.
Option 2 I have an electric motor with a 100mm pulley on it and a 150 (or whatever, but the same ratio) on the saw.

I turn the electric motor on ....(same hp motor on both options)
Which option will initially move the saw blade quicker ....?

[green machine]

There was a bit of confusion goin on with greenies KXF450 which IS a fire breathing 4T MX and my very rider friendly 4T Enduro

Well lads....for the record i've just been testing the bike in the paddock with a 14t front sprocket and i regret to inform you all that the KX is still a firebreathing beast......i wouldn't say it tamed anything down....so i'm gonna take a couple of cement pills and take her out for a strop at Port Waikato and try and dominate her....hahaha,Cheers for the input

[krad_nz]

Its called a mechanical advantage,
Ill try one more analogy
Option 1 I have an electric motor with a 50mm pulley on it and a benchsaw which has lets say 200mm diameter.
Option 2 I have an electric motor with a 100mm pulley on it and a 150 (or whatever, but the same ratio) on the saw.

I turn the electric motor on ....(same hp motor on both options)
Which option will initially move the saw blade quicker ....?

In your example it should be 50 mm & 200mm vs 100mm & 400mm.
The mechanical advantage aka gear ratio is the same. A 100mm & 150mm system would run slower though. Assuming the saw blade is at the 150mm end.

Or am I missing something here?

Unless you're describing taking up the initial slack in the system? In which case the saw at the end of the 100mm system would be the faster of the two given the same amount of slack in each.