final drive sprocket with CNW ?

Hello all. I am using a 21t drive sprocker with a CNW e start and it seems too tall I have a 19,, rear 100/90 roadrider Mk2 . I have yet to check the spedo against another vehicle but the bike seems to be cantering through town traffick . How manny revs @50 kph -35mph with this setup? Any advice appreciated . Cheers Ian

I have 21t on a cNw 850 and it seems fine to me.
38mph (60 km/hr) is just under 2500 rpm in 3rd (a bit over 2100 rpm in 4th - but I don't use 4th around town)
50mph (80km/hr) is just under 2900 rpm in 4th
62mph (100km/hr) is 3500 rpm in 4th

I calibrated my Smiths electronic speedo using a app called Speedbox - just duct-taped the phone to the tank-top.
Cheers

Oh - I have an 18 rear - but the same(ish) rolling diameter as the stock 19 - 671mm (4.00 - 18 Avon Roadrider Mk2}

Ian James said:

Hello all. I am using a 21t drive sprocker with a CNW e start and it seems too tall I have a 19,, rear 100/90 roadrider Mk2 . I have yet to check the spedo against another vehicle but the bike seems to be cantering through town traffick . How manny revs @50 kph -35mph with this setup? Any advice appreciated . Cheers Ian

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Final drive ratio on a CNW estart is nearly the same as a stock bike.

I have a 21T as well, and I rarely take it out of second in traffic in town,

Thanks for replys .First time back up after 9 year lay up /resto so maby at 71 I am a little more nervy around trafic. Will take it easy and feel my way . Other wise couldnt be happier

Ian James said:

Thanks for replys .First time back up after 9 year lay up /resto so maby at 71 I am a little more nervy around trafic. Will take it easy and feel my way . Other wise couldnt be happier

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I'm starting back at 71 after a 35 year hiatus. The 1st 100 miles were a bit tense, but I'm getting the feel back.

I run a 21 tooth on my 74 850, am thinking about a 22 tooth as the 850 has copious torque.

I find a 20T a good compromise for mixed riding. Gives a good gear spread for city/highway riding, while keeping the revs in the smooth zone (3000 +)

50mph+ : 4th gear
40-45 mph: 3rd gear
30-35 mph: 2nd gear

Will still easily do 90 mph in 3rd if you need to pass someone badly .

FWIW

I have an 850 with 23T. Some thoughts:
It is probably too highly geared for best performance, but I love its torquey feel, understated performance (always goes faster than it feels) and low revving comfort. At 70mph it's at 3600rpm indicated. I always get off after a ride, impressed with the bikes easy grunt.

This set up wouldn't work if your isolastics are set to allow vibration below 3,000rpm - Since I retorqued the engine mounts, it's vibration is minimal above 2,000rpm and really sweet >2500 and the handling still feels predictable and solid. Taking it easy, I change to 2nd around 25mph, 3rd at 40 and 4th at 50. Over 5500rpm in 2nd is court appearance territory on the country lanes around here.

I guess it all depends on riding style (I like how the bike feels between 2500 and 4500rpm) and how the bike's set up. Also, I have a modern Japanese 4cyl, which gives me my higher revs fix. When the time comes, I'll try a 22T as it might be the best compromise, for me and where I most regularly ride.

robs ss said:

Oh - I have an 18 rear - but the same(ish) rolling diameter as the stock 19 - 671mm (4.00 - 18 Avon Roadrider Mk2}

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I am running the same as Rob.Went up from the 20T
Mike

Th.e OP doesn't say whether his bike is 750 or 850. The 850 can tolerate taller gearin than a 750

triumph2 said:

Th.e OP doesn't say whether his bike is 750 or 850. The 850 can tolerate taller gearin than a 750

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Sorry 850

Ian James said:

Sorry 850

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As you can see, Ian, there is no one perfect answer that suits every one. But there is likely an ideal answer for you, based on a number of factors:
-How fast do you normally ride?
-At what RPM do the vibrations set in with your isolatics (typically below an area in the range of 2500-3000 RPM)?
-Do you need to be able to have reserve power on tap for hills or passing? Do you mind down shifting to get it?
-Do you ride on motorways a lot, or avoid them and ride secondary roads?

There may be other factors, but being able to balance all of these things, while staying out of the vibration zone as much as possible should give you your answer.

HTH

Further to gortnipper's comment about the CNW ratio being almost the same, this is from the CNW website:
"2.188 gear ratio (std chain drive is a 2.19 ratio)"

Let's call the primary ratio identical, for all practical purposes.
In which case this thread has nothing to do with CNW and everything to do which final drive sprocket different people like for their particular bike.