Installing 19'' Snowflakes

[Julio A.]

Hey Guys, during one of my picks from the nearby provinces in the Philippines, I had the opportunity to get a crate load of R100 and R75 parts. Interestingly, I acquired an almost new condition 19'' snowflake wheel from an R100RS, complete with dual rotors and bearings.

My 18'' front wheel has this large flat spot on it due to somewhere along its life, the bike rammed something hard or fell on a pothole of something. As well as assorted nicks and minor deformations. The rims still holds air and is running good for the past 5 years of my use, but it has this tendency to vibrate and wobble at certain speeds and engine RPMs.

Besides rendering the fender unusable when I transplant the 19'' on the bike, are there any other repercussions I may encounter that I have missed?

[Barry]

Are you considering maintaining geometry by raising the fork tubes 1/2" in the yokes.

[Tony Smith]

You will also need the axle & spacer specific to the 19" wheel, and given the R65 forks, you may need to custom make it.

[montmil]

That hefty steel fork brace under the front fender is there for a good reason. That's going to be the nut to crack as the fender is above the brace.

[Barry]

Careful choice of tire might minimise the overall increase in diameter. A 90 aspect ratio tire would be a little smaller that a stock 3.25 - in theory almost 2/3" in diameter but you'd want to check the manufacturers data.
Maybe you could even get away with the stock fender.

[mrclubike]

I would rather have the 19inch
I wonder why BMW switched to the 18 inch wheel any way.
It may have been for styling reasons. Who knows
I wish they would have stayed with the 19 because we would have more tire choice.
Keep us informed on how this works out
Some of us may want to do this

[Barry]

I don't think I've seen a definitive explanation of why the switch from 19" to 18" wheels.  In the period sales brochures R45/R65's were marketed as the "compact Range" so lower weight and lower seat height would both have been targets to meet and the 18" wheel would have helped in that respect.

On the plus side at least we didn't get the recall and our 18" wheels still look as the designer intended without the strengthening webs adopted for the 19" versions.

[Julio A.]

Are you considering maintaining geometry by raising the fork tubes 1/2" in the yokes.

Yes I do. I don't want to disturb the way the bike handles at the moment.

In hind sight, I do have a spare set of Koni rear shocks meant for the R90/6 somewhere at the back. I'm not touching them since they are around 1.5'' longer than the R65 ones. I'm entertaining the idea of raising both front and rear wheels. Height won't be a problem for me.

That hefty steel fork brace under the front fender is there for a good reason.

Yeah, I already threw that away and fabricated a more substantial brace made from steel tubes and plates. I can easily make a new one to hold the fender higher. Or I can just have a spare police fender I got from an cafe racer'ed R100 lying around here copied and adapted to fit the R65.

I don't think I've seen a definitive explanation of why the switch from 19" to 18" wheels.

This is exactly what's bothering me at the back of my mind, economically, BMW would just use the 19'' on the R65 to save up on manufacturing costs. There has to be a really good explanation why they have to make 18'' wheels just for a single (entry level) model.

18" wheels still look as the designer intended without the strengthening webs adopted for the 19" versions

The wheel I got is not the recalled ones. It's still the original version.
I'm actually contemplating on whether or not to have it replaced, I already confirmed that the nearby dealership will honor the snowflake recall, but putting it in an R65 would subject it to way less stress than it would on an R100.

[Matt Chapter]

putting it in an R65 would subject it to way less stress than it would on an R100.

Does not compute.  You're still going the same road speed, hitting the same potholes.  Some quick googling shows the R100 was only 30ish pounds heavier than the R65.

[Tony Smith]

The wheel I got is not the recalled ones. It's still the original version.
I'm actually contemplating on whether or not to have it replaced, I already confirmed that the nearby dealership will honor the snowflake recall, but putting it in an R65 would subject it to way less stress than it would on an R100.

You will find that your Dealer will want to see the whole R100 the 19" came from before giving you an exchange wheel, they need the engine/frame number.


However, if the wheel you have is in good condition I would not stress about it. The real reasons for the recall are lost in the mists of time, but as your wheel proves, there are still many of the original wheels still out there.

Yet nobody has ever heard of a 19" front wheel failing in anything other than readily explicable circumstances.

The topic of "should I use an original 19" wheel" is a hoary old regular in forums and the consensus of those who have thought about it is  use them with a clear conscience.

[Julio A.]

You're still going the same road speed, hitting the same potholes.  

Ok, so maybe, it's not that WAY smaller, but I swear the fairing on the RS model is already 30 pounds. That thing is freaking heavy.

You will find that your Dealer will want to see the whole R100 the 19" came from

They just need the registration and the VIN. Non appearance is ok.

BTW, I just bolted the wheel on my bike. The axle was too short and the wheel spacer was too long. As you predicted, I replaced it with a spare R100 axle and replaced the wheel spacer with a 7.5mm wedding band. It went in just fine. The wheel actually cleared the fender. The major problem is that neither the R100 nor the R65 disc rotots centers on the caliper. The offset is somewhere between the two standard sizes.

[georgesgiralt]

Hello !
The then new R45/R65 were made to be more agile/manoeuvrable.
The rationale behind that those bikes would lead the rest of the flock to a more "in the mood" bikes. (at that time, having a 16" front road was THE thing to have. ) The customers were reluctant to ANY change (the change from poorly made Hella controls to the same of high quality made in Japan, for example)
BMW had a hell of an advance because it defined a bike with the same front and rear wheel size at 18" diameter.
Look at ALL the current production : both wheels are 17 " for street bikes. Not so bad given these bikes where out in 1978 ...
At the time I wanted to buy a BMW bike. New.  I tried an R80 and an R65. (same horsepower, near same price, same maker.... ) well the R80 was a heavy and slow reacting bike. The R65 was as agile and fun as were the current jap's production of the same horsepower...
So I bought the R65 and did not regret it.
IMHO, putting a 19" front wheel is a mistake. but YMMV...
P.S. : the front snowflake 18" rim was modified too. I had both before and after the mod. It is less apparent than on the 19" but it is there.

[Barry]

There was no recall on the 18" front snowflake so they were left in service.  Did they modify the 18" wheel at some point it in a subtle way that is not visually apparent ?

I agree about the fashion for small front wheels being a possible influence on the choice of 18" for the type 248. I remember it at the time and as in most cases the fashion went too far down to 16" before come back up a little.

[georgesgiralt]

It is not only fashion. Reducing wheel diameter reduces unsuspended mass and makes inertia lesser. This has a very positive influence on handling.
The calculation for mass reduction was giving 16" IMHO. But this made for a not so good handling.
This is why the 16" went to 17" which is a very good compromise. Even better is that the same diameter applies to the front and rear wheel. This makes for roughly the same inertia (given the mass of the tyres) and this is also very good for handling.
BMW reduced front wheel mass going to 18" and also inertia and, given the customer did not buy it, stopped here.
But the K bikes have the same diameter wheels front and rear... and the study for the K was in the pipeline at the same time the R45/R65 where devised.

What is mood, IMHO, is inverted forks. As the tubes are way bigger, I wonder if there is anything to gain on the unsuspended mass and the reversing makes keeping the fluids in a nightmare. So it is an expensive fashion/look change for little or no gain... History will tell us if it keeps ...


Edit : I forgot to tell that the actual 18 " front snowflake rim has been modified too and reinforced. I had the original and a new one in my shed. As the original was too much distorted to be repaired I recycled it so can't make a picture, but the "spokes" have "wings" added to reinforce them. It is obvious when you look at them side by side.

[Tony Smith]

I agree about the fashion for small front wheels being a possible influence on the choice of 18" for the type 248. I remember it at the time and as in most cases the fashion went too far down to 16" before come back up a little.

Made for some truly frightful handling bikes that is for sure. IMHO the only manufacturer that ever made 16" tyres work was Kawasaki and they did so just in time for the wheel of fashion to turn again.

Where I live we have sugar mills and those mills have their own private narrow gauge railways to deliver cane to the mills. These railways never presented much of an obstacle to motorcycles (but were and are deadly to cyclists) but during the great 16' front wheel era motorbikes were constantly coming to grief on them.