Steel or Aluminum?

[jwonder]

Calling all off-road aficionados!

I am building an ISDT (copy) R 50/2 and I AM planning on riding it off-road. What is the best rim material to use for this off-road build, Steel or Aluminum? I have heard varying ideas on what rim type to use and why, and I am almost to the point of making this choice and wanted to query the source of all knowledge (the forums) for advice!

Any thoughts or advice in either direction are appreciated!!!

[Slash2]

I would think if all options were on the table aluminum would be the superior option. It is lighter, and likely stiffer than steel.

I have a 1955 R50 that I bought as a basket-case about 10 years ago. This has always been my plan for this machine and I'll be following your progress with keen interest. A fellow club member built one of these a few years back and it was featured in the bulletin. Since my project is missing much of her original parts, a correct resto seems unnecessary and I have enough standard machines. An ISDT machine would be so much fun and much more practical where I live. For 2 years I rode a 1965 R69S as my on/off road bike until I found an R80G/S which is so much fun but a small R50G/S would be so cool. I love the look of the R27G/S as well. I've never found a hill my R27 couldn't climb. The gearing really helps.

[malmac]

Hi James

I am no expert on this subject.

What have I observed in actual experience.

The R1100GS and the R1200GSA I have, both sport alloy rims and are much heavier bikes than what you are planning.
So on that basis one might add a big plus for alloy.

I see modern dirt bikes which have beautiful alloy rims, lighter than your build, however still modern rim design and alloy type.

I had an R90/6 with alloy rims and the rims were soft and dented even ridden on the road.

So the challenge might be getting the right alloy rims. Old ones from the era seemed to have been built for solo bikes and side cars had steel rims. If I was using period rims, unless there were special ISDT rims (which lets face it only had to last 6 days), I would use steel rims.

Mal

[R68]

Factory ISDT bikes in the 50's and 60's were equipped with steel rims. Keckheisen makes very nice replica ISDT parts. The compressed air tank can be made from an early pattern 5 liter propane gas tank, easy to find in Germany. I'm not sure if the R50/R60 ISDT exhaust is available? There'a a fella out east who restored a very early factory R50 ISDT originally owned by some pinko professor from Columbia U a few years ago, who will be a great source of info for your project...good luck.

[Flx48]

My two cents James-
If thinking of using original rims, then for sure use the steel, because as we know, while both suitable and desirable for use on roads, the Weinmann rims can be bent with a harsh stare, so one would think entirely unsuitable for actual dedicated offroad use on an overweight bike like an R50.
For period aftermarket rims, both Dunlop and Akront alloys would be suitably strong; don't know when Dunlop stopped, but Akront were produced right into the eighties, (got some from Buchanan then) but finding some now that were drilled for the /2 might be hen's teeth..
If talking modern aftermarket rims, then the Jap Excel alloys would definitely be up to task, or if wanting to stay Euro then no doubt the repops of Dunlop and Akront would suit, currently made by Devon and Morad respectively, I think both using the original dies.
Sounds like a fun project!
Best-
George

[jwonder]

R68, I have contacted Keckheisen and I might use some of his parts. He does very nice work. I don't think I will be putting the compressed air tank on, but I might; who knows. I have an exhaust already, an original one, and will likely use it to copy from. The original was VERY thin and light and fully brazed together. I am not sure I want to crunch that the first time I fall so I will likely weld up a new one myself. I would feel better crunching a replica.... I wrote an interview with Mike, about his R 50/2 ISDT motorcycle, in Volume 45, Issue 4 of the magazine. Its a great writeup and is what made me want to create one too and actually go beat the crap out of it!!!!

So, it looks like I will be going with new steel instead of vintage aluminum simply because I do not have steel rims, just aluminum ones on hand. I agree that current/new production aluminum would be best, but I am looking for this to be as "close to real vintage" as possible and mirror what they did in the ISDT days as good as I can. Re-pop steels are available and even with some of the issues with the welds, they are good enough for me to beat the heck out of on the trail!

Maybe I can find a set of older, original steels with some rust on eBay that I could use.

[cwf]

You probably saw this one a few days ago, maybe /5 rims. I used a 75/7 off road in UK and in Turkey and another 75/7 with off-road sidecar off road in UK on standard BMW alloy rims and had no problems. A few spokes broke, the seals to the wheel bearings were not up to much water exposure. The sidecar bike now has a 21" BMW alloy front rim, again no probs.

Charlie.

[Jim D 5112]

I have a pair of steel /2 rims that are not rechromed but in descent condition. They could be replated or used as they are.You can PM me if interested.