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Old 10-30-2012, 07:17 PM   #1
DiabloADV OP
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Final drive Q...

The two airheads I have (R60/5 in parts, and R90/6 "dirtbike" being restored) both came with 37/11 final drives. Am I right in thinking this ratio is not ideal for highway miles (ie, dualsport) on the R90/6 (which is actually 1000cc)?

What ratio drive should I look for for all-round riding (ride the highway to the trails, and then ride on the trails)? I can always keep one of these for a genuine offroad trip.

And...anybody want to trade me a higher ratio drive for one of these low ones?
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Old 10-30-2012, 07:41 PM   #2
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ratioring/pinion teethrpm @55mphrpm @70mphspeed @7200rpmspeedometer ratiousual model
2.9132/11305038811301.078R100
333/11314740051261.112R90S-R100
3.0934/11324141251221.144R90-R100/7
3.232/10335742731181.186R75-R80
3.3637/11352544861121.244R60-R75
3.4431/9360845921101.259
3.5632/9373447521061.318R60-R65
2.6234/13This was for racing, /5 and later
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Old 10-30-2012, 08:28 PM   #3
pommie john
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The normal drive on the 900s is a 33/11 some had a 32/11 but if you find one of them, sell it on ebay they're quite rare.
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Old 10-30-2012, 08:54 PM   #4
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pommie john, Which one are you saying is rare? All the RTs and RSs came with the 32/11, which in the day were called the Autobahn rear end as with it you got the highest top speed. The 33/11 was also very commonly found on a lot of other bikes, including some R90s and R100s. It was also a factory option for the R80s of 1978. I know of at least 3 R80s near by with the 33/11 and a lot more with the 32/10 and 2 that have the 37/11 which was called the Alpine rear end due to it being very popular with those that did a lot of mountain riding. In the mid 70s thru early 80s, you could order different rear ends on the bikes, if you were willing to wait for it to get shipped.

But, you could also pick your bike up at the factory or one of the dealers in Germany, back then as well. You just had to make the arrangements thru you local dealer and pay up front for it. I did just that in 1979 for a brand new R100RT, I got to ride it all over Europe with my wife, then take it back to them and they packed it up and arranged the shipping to Montreal where I picked it up again and road across Canada to home. They don't do that anymore, which is too bad. It was a great arrangement for a minimal extra cost. I think it was an additional $250 back then. Would probably be around $5000 now.
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Old 10-30-2012, 10:36 PM   #5
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So...sounds like I should be looking for a 33:11 for highway and backroad riding, and keep one of my 37:11 drives for offroad/mountain trips.
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Old 10-30-2012, 10:39 PM   #6
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I have a stock 33/11 on my 88 R100 RS - and although it won't have the top speed on the highway that the 32/11 would, it'll still ride all day at 80 mph plus and hit over 100 without any complaints.

I think the 33/11 is better in real world back-road/country or urban anyway - torquier off the line, better low end usability.
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Old 10-31-2012, 12:26 AM   #7
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I would think the 37/11 would be about right for the R60. My '83 LS would cosistanly pull its 7650rpm redline in top gear and sometimes then some with its 32/9 but I guarantee you that a '81 on R65 runs a lot stronger than your R60. Hell, my R69S ran a lot stronger than any R60 I ever rode with. I don't think your R60 will pull a 37/11 but most people don't really care about that anyway. I like 32/10's on 900's. If your 1000cc 900 is running real strong, you'll like a 33/11. A 32/11 is faster than a 33/11? Just because a bike has taller gearing does not mean it will pull the taller gearing. There are a lot of airheads out there that would pull a faster top speed with a higher gear ratio than a 32/11! It would take one long down hill and a strong tail wind for many an airhead to pull redline with a 32/11. IMO, your wasting good engine if you can't pull at least redline in top gear but a lot of people love to gear them to the moon although they are never going to get out of orbit!

supershaft screwed with this post 10-31-2012 at 12:37 AM
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Old 10-31-2012, 05:01 AM   #8
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Quote:
Originally Posted by Zodiac View Post
I have a stock 33/11 on my 88 R100 RS - and although it won't have the top speed on the highway that the 32/11 would, it'll still ride all day at 80 mph plus and hit over 100 without any complaints.

I think the 33/11 is better in real world back-road/country or urban anyway - torquier off the line, better low end usability.
Another vote for the 33/11
Road, dirt, trail.
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Old 10-31-2012, 07:25 AM   #9
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Out of curiousity, what size is the rear wheel? If it's a 18" then I wouldn't go taller than the 34/11 ... if it's the 17" then the 33/11 is fine. The stock FD on my '91 R100GS is a 33/11 with the 17" wheel. The Dobber (R100) currently has a 18" rear wheel, and the 37/11 ... and it's too short. On loose dirt, it's difficult to not spin the tire. I'll put a 32/10 on it (I have one on the shelf), and I think it will be a fine medium for road and dirt.

I have to say though, the 18" wheel + the 37/11 ... I can go 80mph @ 5,000rpm. That really is a sweet spot.
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Old 10-31-2012, 08:54 AM   #10
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I have 17 for road and 18 for offload.
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1974 R90/6 w/1050 kit. Motor only. Seeking a frame.
1970 R60/5

'91 Bill Holland Steel w/Dura Ace
'01 Z3 3.0 Coupe. The Clownshoe.
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Old 10-31-2012, 01:45 PM   #11
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Quote:
Originally Posted by DiabloADV View Post
I have 17 for road and 18 for offload.
If you plan on swapping wheels for the specific purposes you described above, I'd get the 33/11 or the 34/11. You'll be very happy with both. Taller all around, and if you put the 17" on for dirt, you'll have plenty of room within the gear for off road fun.
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Old 11-01-2012, 01:17 AM   #12
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Quote:
Originally Posted by DaveBall View Post
pommie john, Which one are you saying is rare? All the RTs and RSs came with the 32/11, which in the day were called the Autobahn rear end as with it you got the highest top speed. The 33/11 was also very commonly found on a lot of other bikes, including some R90s and R100s. It was also a factory option for the R80s of 1978. I know of at least 3 R80s near by with the 33/11 and a lot more with the 32/10 and 2 that have the 37/11 which was called the Alpine rear end due to it being very popular with those that did a lot of mountain riding. In the mid 70s thru early 80s, you could order different rear ends on the bikes, if you were willing to wait for it to get shipped.

But, you could also pick your bike up at the factory or one of the dealers in Germany, back then as well. You just had to make the arrangements thru you local dealer and pay up front for it. I did just that in 1979 for a brand new R100RT, I got to ride it all over Europe with my wife, then take it back to them and they packed it up and arranged the shipping to Montreal where I picked it up again and road across Canada to home. They don't do that anymore, which is too bad. It was a great arrangement for a minimal extra cost. I think it was an additional $250 back then. Would probably be around $5000 now.
Maybe they're more common on your side of the pond, but when I was looking for ratios for my race bike the wreckers were full of 32/10, fewer 33/11 and 32/11 were hard to find in the UK.
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Old 11-01-2012, 05:17 AM   #13
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Quote:
Originally Posted by pommie john View Post
Maybe they're more common on your side of the pond, but when I was looking for ratios for my race bike the wreckers were full of 32/10, fewer 33/11 and 32/11 were hard to find in the UK.
The 32/10 is 5% (or so) taller than the 37/11. I'm going to put that on my dirt bike. That with an 17" wheel is perfect for dirt ... put an 18" wheel on it for road, and you'll cruise at 80 mph all day at 4500rpm.
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Old 11-01-2012, 12:59 PM   #14
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Quote:
Originally Posted by pommie john View Post
Maybe they're more common on your side of the pond, but when I was looking for ratios for my race bike the wreckers were full of 32/10, fewer 33/11 and 32/11 were hard to find in the UK.
32/11's are the shit here in the states and are the most sought after ratio although I think they are too tall for most airheads. In my experience, 34/11's are the rarest. I have never even looked into the taller than 32/11 situation. I will never have a bike that could use it!
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Old 08-01-2013, 03:15 PM   #15
Jim K in PA
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Kicking this (great, informative) older thread to the top to get some feedback on low speed technical riding (picking a line through rough stuff, etc). My '79 R100T has its original 32/11 final. With a 120/90-18 rear tire, I feel I have to slip the clutch too much to keep it from stalling on some steeper, rocky hills. And that was with no extra gear (weight) on the bike.

I just replaced the 120/90 rear tire with a 4.00-18, which is narrower, but even taller. Should I look for a 32/10 or a 37/11 final to keep the revs a bit higher at low speed? Or is the difference between the two (only 5%) not worth worrying about?

I am not an 80mph highway kind of rider (no faring). If I have to slab it, I prefer 65-70 max unless I am passing someone. Overall I prefer back roads at 50-60 and dirt roads & trails at a lot less!

Thanks for any more detailed BTDT input.
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