20 vs 21 sprocket tooth

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I’m running a 21. If I could be bothered to strip the bloody primary down (which I can’t), inc cNw electric start, I’d change for bigger, it definitely feels like it would handle it easily.

I’m cheating slightly though as it’s a 920 !
 
By spending way too much money to replace the low gear set for more rpm at a walk.
I forgot to remind all AGAIN that I weigh less than most teenagers. Im sure this counts.
If you have a 920 you likely have a lot more umph. But then you have a lot more weight.
I guess do the maths...
 
Onder said:
By spending way too much money to replace the low gear set for more rpm at a walk.
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How much roughly, can you remember ?

Is it a straightforward job ?

Would you do it again ?

I’m thinking that doing that, and using a 23 tooth, might give a great ‘spread’.
 
I have to take the old lady to the local for lunch Ill get back to you later.
 
Fast Eddie said:
I’m running a 21. If I could be bothered to strip the bloody primary down (which I can’t), inc cNw electric start, I’d change for bigger, it definitely feels like it would handle it easily.

I’m cheating slightly though as it’s a 920 !
Click to expand...
22 & love it.
80-85 in modern expressway rush hour traffic? No problem.
4000 at 80mph
Tight mountain roads? 1-2-3 as needed. Never a wish for lower gearing.
 
My 850 came with a 23t sprocket.... plus a shed load of other 'bodges'. Now runs 20t which seems adequate cover for country 'bimbles' and motorway games when the urge sets in :)
 
I noticed Andover is only out of stock of 21T sprockets, so they must be popular.

Don't think a one tooth difference is worth the effort, so believe a 21T is the way to go.
19T is good on the fast canyons until I hit 70-80, or on freeways traveling to and from.

Hardly ever need to downshift to 1st or even 2nd, in the riding I do. That would certainly change, with my 750.
 
Fast Eddie said:
How much roughly, can you remember ?

Is it a straightforward job ?

Would you do it again ?

I’m thinking that doing that, and using a 23 tooth, might give a great ‘spread’.
Click to expand...
If you have the top four gears close together and high, with a very low first gear, you have to live with the gap between first and second. But most guys don't go below second once they are mobile. If you use a four-speed AMC box, the first gear from all the very old Norton gearboxes fit them.
 
When I was using the close ratio four speed box, my bike used to just lumber off at the start in races, I was too dumb to think about the two old gearboxes I have in my shed. I also have the normal Commando box. Even the first gear out of that would have been better. Four gears are enough, but I bought the six-speeder - dumb ? I would have coped easily with the gap between first and second. All you need to is rev the motor higher in first gear and be careful when you change down to first. - (Suzuki T250s are like that as standard.) I have a friend who races a 500 Manx with a speed box - he has three first gears which he uses to suit various race circuits.
 
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The difference is - the AMC four speed close ratio cluster costs $700. The six speed TTI box costs $5000.
 
FE: low gears
31 tooth on the countershaft for NZ$150.00.
2.51 ratio.
16T on the input NZ$140.00.
You obviously have to strip the primary but the main and counter shafts will slide out cassette style.
 
Onder said:
FE: low gears
31 tooth on the countershaft for NZ$150.00.
2.51 ratio.
16T on the input NZ$140.00.
You obviously have to strip the primary but the main and counter shafts will slide out cassette style.
Click to expand...
Thanks.
 
Just got back from verifying that 20T does indeed do the deeds required by me. Plenty of acceleration from a 60-90mph roll on and the awesome Commando pull through the rest of the gears with minimal vibration whilst farting around in general. Conclusion is unless I wake up in the mountains no changes required.... All of this reading warranted a ride to prove I'm still alive gentlemen.
 
back in the day started with standard 19T on my '72 750 Roadster , switched up to 22T , maybe too big a jump after first season , down to 21T the next and have left it in place since , performs very well for my type of almost exclusive backroad rides , no plans on changing to another size .... very pleased !
 
If you intend to raise the overall gearing, you probably need close ratios. I tried racing with the standard Commando box and it was appalling. If you lose too much on every gear-change, raising the overall gearing makes it worse. With a close box, the next gear is always in the right place when you need it. Throttle response is poor when you have a heavy crank, but you use the crank inertia to advantage when you use it right.
 
Remember that you are a track man and most of us are road users. So what works for thee hardly would work for us.
 
jbruney said:
Just got back from verifying that 20T does indeed do the deeds required by me. Plenty of acceleration from a 60-90mph roll on and the awesome Commando pull through the rest of the gears with minimal vibration whilst farting around in general. Conclusion is unless I wake up in the mountains no changes required.... All of this reading warranted a ride to prove I'm still alive gentlemen.
Click to expand...
If you do wake up in the mountains the 20 tooth works very well there, a little better than 21 tooth, in my experience.
 
Mine's close enough on the road to keep it bawling like a hungry calf when I poke it good.

Took that Goldwing through the mountains years ago and was that tall geared booger ever a trip... Kept having use the brakes coming down.... using engine and gearing didn't workout well with it. Almost smoked them.
 
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