|This page is about the alloy rims on BMW motorcycle models R26, R27, R50, R60, R69, R50/2, R60/2, R50S, R69S, R50/US, R60/US, R69US. Little of this applies to the steel rims.
Steel or aluminum?
This is an attempt to explain some of the confusion concerning the choice of rims used by BMW. BMW offered both chrome plated steel and alloy, or aluminum rims. I only watched BMWs on the show room floors from 1962 and later. I will only be guessing about earlier year production. Each year BMW offered one type of wheel as standard and the other one was an accessory that cost $25 extra. One may see this on invoices from that era. Steel would be offered for a year or two and then alloy would be offered as standard for a year or two. For a year or two the sport models (R69S and R50S) were only available in aluminum while the R50/R60 was steel as standard. Some dealers kept new wheels in both types to offer up a choice to any buyer. Owners would decide to change the type of wheels and buy new ones of the other type. There are so many variables involved that without a series of invoices of each year, we will probably never figure out what was correct for any one year.
The question has come up concerning the year that BMW changed from using the low lip alloy rim and started using the high lip rim. This is of interest to restorers that care about getting it correct. The first years (late 55 thru early 57) the alloy rims were the high lip variety. Then they went to the low lip rims for several years. Around 1961 BMW began using the high lip rims again. The early rims have the early spoke pattern and are now extremely rare.
Does your BMW motorcycle even have a Weinmann rim?
If your alloy rim isn’t a Weinmann then it is not correct for a /2 BMW. Some recent aftermarket rims, reportedly from Italy, are available. The first one that I saw was as a result of taking a glance at a friends restoration. His spokes weren’t in the correct configuration and I commented on it. He explained that it was caused by the incorrect rims. The spokes touch each other and actually bend around each other slightly. The correct rim for a BMW will have the spokes passing by each other with about 1 mm, or less space. If you don’t have a Weinmann rim, this page doesn’t apply to your rims. The Weinmann rim can be laced up backwards, but the spokes will have to bend around each other and be crooked.
A Weinmann stamped rim
A review of the two types of alloy rim.
The low lip rim The high lip rim
If you had one of each in front of you, it would be very easy to see the difference between the two. I found it harder to photograph. I was able to stand a dime up in the groove to show the difference in radius. The dime in the low lip rim almost “fits” into the groove. The dime in the high lip rim doesn’t drop down into the groove, and allows lots of light come through below it.
The low lip rim The high lip rim
Here you see it with a wire laying on the high center part of the rim. On the low lip rim it has far more distance down to the lip. On the high lip rim it is nearly touching the lip.
The date of Weinmann rim manufacture for BMW motorcycles.
The early series Earles fork BMW from 55-mid 57 has a different hub and spoke pattern. As a result, the spokes are shorter. More useful info on this issue in another article. Some of the sport model R69, had a high lip rim. That rim is different than the later high lip rim due to the spoke angle etc. Little is known (by me) about this early high lip rim. It seems that the high lip rim disappeared from mid 57 to around 61.
Low lip date 7/59 High lip date 3/65
The date of manufacture is clearly stamped on the inside of the rim across the valve stem hole and in large numbers. The latest year, so far, of a low lip rim is late 1961. Can someone find a later one? I think that the earliest date of a high lip rim is around 60-61. Can you find an earlier one? The high lip rim may have been introduced with the /2 series in 61, but I just don’t remember.
The size 2.15 X 18
The rim size is also stamped into the inside of the rim across from the valve stem hole. It is much smaller than the date and harder to read. It is of no significance to anybody. As far as I know, only one size was made in alloy. Two sizes were made in the steel rim, one for solo and a wide one for sidecar.
Other points of interest about BMW motorcycle rims
To restore a rim may be necessary because we just can’t buy these old rims today. A rim may seem to be pretty far gone and still be restorable. I think that it depends upon your standards. I have “saved” some poor ones and here is what I have found worked for me.
First I clean it off. Now we have some great cleaners and the one that I use is Super Clean, by Castrol. This stuff is nuclear powered and can be dangerous on some things, like your skin and respiratory tract. Use it in an open place and rubber gloves are advised. It seems to be safe on metal, but on plastic, I would first try it on an “out of the way” spot.
This takes off most of the road grime. Most rims are going to need some major polishing. I highly recommend doing it by hand. You will get a much better job and cause far less damage than the job done by a buffing wheel. Some have reported the bumps for the nipples to have gotten polished down when the polisher forced the rim against the wheel trying to get into the corners.
Expect to put 5 hours into the polishing part, maybe much more. I use an old worn out Scotch Brite pad for gently cleaning the grime off. One must be very careful on one aspect of cleaning. On the inside of the rim where the sidewall of the tire contacts the rim (the seating area) is a series of dents/scrapings pressed into the aluminum. This raises the metal around the dent and makes a sharp protrusion to help grip the tire. This is to help keep the enormous horse power of the /2 from spinning the rim within the tire. That would cause the valve stem of the inner tube to get “ripped out” and it happened to me on my first BMW and on my first long trip in 62. More info here.
The knurling (serrations) for gripping the tire.
If these marks are still original then one can easily feel the sharp edges with fingers. Be very careful to not sand/grind/polish them down to smooth. These tend to fill up with tire rubber compound and seem smooth. I allow the Super Clean to soak for a few minutes and then use a brush to clean the cavities and seating area. Often one can see a large black marks on the seating area where tire rubber has gotten stuck. It comes off easily and should be removed.
One of the most common things for the alloy is for it to get pitted badly. That can be cleaned off with CRL, a chemical for cleaning off calcium, rust and lime. It is available in any grocery store. It will chemically get the white stuff out of the pits. You may not want to see how deeply the pits can go.
Dents and dings in a BMW alloy rim
After 50 years it is almost impossible for the rim to have always had a knowledgeable owner/mechanic change tires. This means that they didn’t know about the 5 dents and how important they are. One must also pay special attention to installing the axle.
Not understanding how to change a tire on a BMW can be damaging to the rims and wheel bearings. It is very common to badly damage a rim with the tire irons. Here is an example of what someone has done to this high lip rim.
You can see that the rim has a very bad gouge in it. The rim is actually bent out of its circle. The bend can be easily fixed with a press or simply clamping it in a vise. One must do it slowly. A hammer will ruin the rim. The high part can be filed, sanded and polished down, but still a divot will remain. I have no experience with having someone welding a spot to fix it.
Minor damage from hitting pot holes can also be pressed out of a rim. It can often be done without removing the tire.
This is another view of the same ding. Here it doesn’t look so bad. This rim won’t easily make a perfectly restored example.
One big disadvantage of the high lip rim is that they really catch water and hold it. Once your rims are restored and you ride in the rain, be sure to use a rag to soak up any water caught in the lip. That water sitting around until it evaporates will ruin them. Many had to be tossed because of extensive pitting.
When polishing the rim, avoid much pressure on and around the Weinmann stamp. It easily gets rubbed away. Also avoid a buffing wheel on the raised places for the spokes, as they can be worn down. Spokes have been known to easily pull through the thin rim after polishing.
Read about how to spoke, true and tune a BMW spoke wheel. Be sure to send Lonnie an email to thank him for posting his well written directions.