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Old 09-27-2013, 05:48 AM   #16
patrkbukly
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Damn Daveball...

Quote:
Originally Posted by DaveBall View Post
I have ridden an RT for over 30 years, in all kinds of weather conditions. Something I learned back in 1979, when I picked up my first RT from the factory outlet in Munich. The BMW technical representative went over the bike very thoroughly prior to letting me take it for a ride. He explained every little detail along with some handling techniques that they has worked on, particularly in respects to the fairing and crosswinds. He also stated that top boxes were not recommended for these bikes.

The RT and RS fairings were designed to catch a cross wind and use it to it's advantage. The bike will want to lean itself into the wind. Those little wingy type things that stick out front above the cylinders along with the curved under belly beneath the headlight were designed in the wind tunnel to make the bike catch and control winds.

Now that all being said, and 30+ years later, people today do not have the advantage of being able to talk with people that were there when the bike was originally designed. And, a lot of people that are buying these old bikes, are used to more modern and totally different designs of bikes. The design of the RT and RS are such that they have a forward bias in the weight distribution. They are not neutrally balanced. Then you add on the design of the fairing that the faster your go, will give you even more down force on the front wheel, thus lightening the back one. Put a top box on the back, that will catch wind like a sail, and what happens? The back end will twitch around like a dog's tail.

So, the best recommendation I could make is to get rid of the top box and learn to allow the bike to have it's own head in a wind, to a point. I have always used light hands on the bars and slight body movements to correct direction in a wind. Never found the bike to be difficult to handle in any steady cross wind. Now full blown gales and heavy 50 MPH wind gusts do cause problems, and you probably should be seeking shelter at that point anyway.

Oh, and one other point that keeps coming up. Somebody stated that BMW used cast aluminum wheels starting in 1980. This is totally false. The Snowflake wheels are Cast IRON.
You just taught me a few things. Thank you for that. Good stuff. I have owned R100Gs for a longtime but only recently started riding a 1980 RT and love it. But your info helps a lot AND is consistent with BMW wind technology even today.

Thanks again.
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Old 09-27-2013, 06:38 AM   #17
RayB
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The Snowflake wheels are Cast IRON.
You put this in there as a joke right?
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Old 09-27-2013, 09:22 AM   #18
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Originally Posted by RayB View Post
You put this in there as a joke right?

The cast iron snowflakes were only on the coal fired, steam powered airheads. I'm sure that information is on Snowbums site.
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Old 09-27-2013, 10:27 AM   #19
disston
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Quote:
Originally Posted by robtg View Post
The cast iron snowflakes were only on the coal fired, steam powered airheads. I'm sure that information is on Snowbums site.
I'd like to buy a pair of cast Iron Snowflakes if anybody has any extras they'd let go for a song. I plan to put them on my R90/5 that I am customizing into a MicroWave Oven style Touring Bar Bike.
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Old 09-27-2013, 09:21 PM   #20
Plaka
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Originally Posted by RayB View Post
You put this in there as a joke right?
it's a bit of weidness from BMW itself. Look on some of the online fiches. The wheels are listed at cast iron. I haven't looked in my SNAB but I bet it's there too, it's what the fiches come from. Methinks something got lost in translation.
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Old 09-27-2013, 09:37 PM   #21
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Originally Posted by Plaka View Post
it's a bit of weidness from BMW itself. Look on some of the online fiches. The wheels are listed at cast iron. I haven't looked in my SNAB but I bet it's there too, it's what the fiches come from. Methinks something got lost in translation.

Eggzactly.
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Old 09-28-2013, 01:27 AM   #22
chasbmw
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Quote:
Originally Posted by robtg View Post
Eggzactly.
Mind you snowflakes weigh so much, that you could easily believe that they were made from cast iron
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Old 09-28-2013, 08:57 AM   #23
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Geez, I posted that in April. You guys just catching up now?

Anyway, I can stick a strong magnet to the rim of the Snowflakes on both my present bikes. Weak magnets do not stick. I can only assume that they have iron in the mix of metal used in the casting. The original film BMW fiche all say Cast Iron, as well as the newer electronic versions and the online versions.

I had a front one replaced thru the recall a few years ago. The new one had to come from Germany and on the packing slip it said - 1 Cast Iron Snowflake rim. I keep all documentation on each bike I own. Helps a lot when/if I decide to sell it.

But, by the weight of them, one would think they are made of lead.
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Old 09-28-2013, 09:33 AM   #24
robtg
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Quote:
Originally Posted by DaveBall View Post
Geez, I posted that in April. You guys just catching up now?

Anyway, I can stick a strong magnet to the rim of the Snowflakes on both my present bikes. Weak magnets do not stick. I can only assume that they have iron in the mix of metal used in the casting. The original film BMW fiche all say Cast Iron, as well as the newer electronic versions and the online versions.

I had a front one replaced thru the recall a few years ago. The new one had to come from Germany and on the packing slip it said - 1 Cast Iron Snowflake rim. I keep all documentation on each bike I own. Helps a lot when/if I decide to sell it.

But, by the weight of them, one would think they are made of lead.

Magnet is probably picking up the steel wire in the bead of the tire.
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Old 09-28-2013, 12:15 PM   #25
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Quote:
Originally posted by robtg - Magnet is probably picking up the steel wire in the bead of the tire.
On the spokes? I don't think so. I have also done this when I had tires off and was doing a major cleanup and prepping for paint. No bearings, no tire, no anything. Just a bare wheel.

For those that are so skeptical, just go an get a good strong magnet (not the one off your fridge door) and give it a try. I have done it on several different wheels on different bikes, with different strong magnets. They all stick on quite well. These wheels are NOT aluminum or magnesium. I am certain that there are other metals mixed in but they are definitely cast steel.
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Old 09-28-2013, 12:43 PM   #26
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bullshit
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Old 09-28-2013, 12:52 PM   #27
Plaka
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Originally Posted by RayB View Post
bullshit
Bingo.


I just did it, rare earth magnets in magnet cups. Strong enough to cut you if you have a finger in the wrong place when they get near iron. Zero stiction on two sets of snowflakes. They grabbed the disks, which are a feritic stainless, but not very strongly.
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Old 09-28-2013, 08:23 PM   #28
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Quote:
Originally Posted by Gian4 View Post
I've been riding for over 30 years and I know stiff cross winds are no fun but I don't have past experience on faired bikes to compare too.

Thanks
Gian4
Hello Gian4,

I don't mean to be condescending, but are you allowing the bike to lean to adjust for the cross wind? I often ride in really strong cross winds and as long as I let the bike ('81RS) find its own balance, it tracks straight and true no matter the wind (sometimes really leaned over for quite a distance). If you try to keep it at 90 deg., like a car, it will wonder all over the road. As far as passing big rigs at speed (~ 90) I always tend to lean forward on the tank to keep the bike settled and wobble free.
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Old 09-28-2013, 08:38 PM   #29
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I have to agree that the RS models do self steer into the wind however this trait takes some getting used to. On a recent trip home on the sea to sky highway ( Vancouver to Whistler connector ) the wind was exceptionaly strong gusting across the road. While my RS was stable it still took some getting used to it self correcting into the gusts. As I rode along I started to notice groups of other motorcycles pulled over to wait out the wind gusts.
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Old 09-28-2013, 08:59 PM   #30
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If you had cast iron wheels, crosswinds wouldn't be a problem.
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