beng1

This bike used to belong to an old friend of the family's. He bought it new in Europe in 1938 and then toured with it there right before WWII. He then brought it back to the USA with him before joining the navy and becoming captain of a ship in that war. It takes some really odd 28" tires that are no longer made according to some German enthusiasts, but I did manage to stretch some 27" tires on it at one time, but of course the front brake would not work well with them as they are too small and the brake works by rubbing on the top of the tire. It has a two-speed rear hub and Bosch lights. Someday maybe I will lace some different rims up to it which are easier to find tires for.

Narhay

That's very cool. I like the little emblem on the front fender.

You should check out thecabe. They might have more information on a bike of this age.

dedhed

https://onlinebicyclemuseum.co.uk/fi...tage-bicycles/
https://thecabe.com/forum/threads/re...-tires.143402/
https://thecabe.com/forum/threads/ro...-tires.194428/

https://www.universaltire.com/28-x-1...ire-black.html

RustyJames 

From the Universal tire website;

These tires are intended for display only. Valve stem is non-functional.

RustyJames 

BTW - very cool bike. That would not look out of place in my high-patina collection.

1989Pre 

I like the NSU's. They have an interesting history of building both bicycles and motorcycles. I have wondered: Does the front fender descend to brake against the tire, or is there a curved plate under the fender that descends when the lever is pressed?
Talk to Heinz here:. He might have the tires you are looking for: https://velo-classic.de/oxid2/index.php?lang=0&
There is also a website for NSU.

198

scarlson 

Are the tires just the normal clincher kind, with a wire bead and tube?

If so, it's possible they are just ISO 635, an older roadster and utility bike tire size often also called 28". Worth checking out. Looks like there's still new tires in that size available on ebay.

RustyJames 

635 is a common-ish size tire for Dutch bikes. If that is the correct size, Schwalbe makes them but they have reflective sidewalls which look odd (to me) on vintage bikes.

Dylansbob 

I was able to peel off a reflective strip on a Big Apple without damage, YMMV.

Narhay

One of the links above states that someone had ridden 450 happy miles on these tires without issue but that because it was a cottage industry item for liability purposes it was marketed as display only.

VtwinVince

NSU fan here, especially of the motorbike variety.

repechage

V or Vee rubber from Vietnam also makes that tire size.

The coasterbrake hub points that might be later....Not sure, There often is a date code on the hub shell.

martl

Good advice about Heinz, the size you're looking for is most likely 635-40

Many Sachs rear hubs of that era can be dated.

scarlson 

Yeah, those are nice tires! I had some on a Raleigh DL1 about 10 years ago now. Couldn't find anything in 635 from the usual suspects (ModernBike, BikeTiresDirect) which is why I recommended ebay. They appear to have some Asian-made tires that might look even more period-correct. The red ones, in particular, add a little authentic flair to any prewar bike.

beng1

That was the problem, when I posted it on a German page for old bikes a few years ago they said the rim style was not normal clincher, they were a type that has not been made for years.

The rear hub I think is called a Sachs Doppel Torpedo and it does have a date code from the late 1930s.

The front brake is a shoe under the fender which drops onto the top of the tire, so the tire has to be a certain diameter for it to work well. I had an NSU sport-max a long time ago, but it's forks were bent and I sold it to an old dealer who liked german bikes, my old man was a dealer/racer of British bikes so I was brainwashed into riding them, probably the worst-made motorcycles in history, but they were/are fun.

scarlson 

Sounds like it might just be a hookless rim. Westwood style, maybe? I can't see them really well in your picture. Also known as "chapeau de gendarme", the Westwood rim was often seen on bikes with rod-brakes and 28" (635) tires. Here is a profile of one.


These don't have the bead hooks which are popular on modern clincher rims. But they can handle modern clincher tires! Care must be taken with the bead (avoid kinks, make sure it's properly seated), and you often can't use as high a pressure as you might normally.

Just a thought! If you can get 27" tires on, maybe they aren't 635 - and maybe you could try a larger width of 27" tire. I don't know how hard it may have been to mount them. 5mm seems like a lot, but maybe not.

beng1

The 27" tires were a tight fit on the rim, and in the USA I have not seen tires in that size except the skinny ones for the drop-bar "road bikes" which come in 1 1/8 to 1 3/8" sizes. I ride a lot of old ten-speed road bikes and it is much easier to get the tires off and on them than it was with this bike. I was just thinking of lacing some of the 26" rims onto the bike which was used on the British lightweights with 3-speed rear hubs, they seem easy to find fat tires for. I think the original tires on this bike were 1 3/4" wide, I have one of it's original tires somewhere, and both it's original inner tubes, old Continental equipment, I will take a look at it and confirm it's size.

scarlson 

You can find wider 27" (ISO size 630) tires. The inch sizes are pretty nominal - they don't mean much. I have found that different brands of tires identified as "27x1-1/4" could measure anywhere between 1" and 1-1/2". You have to research actual sizes reported by actual people, to see what's out there and increase your sample size.

Sounds like they may be ISO size 635 then. 27" is 630 so they would be a little bit smaller.

Sure, the EA3 26" (590 ISO) size is easy to find tires for, but it'll be smaller and the bike will look funny, and won't be original, and the front brake definitely won't reach then.

The tires were likely made before the ISO/ETRTO system was invented, so they'll probably not have this size marked. If they are 635, they may also be marked F10, F25, or 700B. There's not a good way to measure the ISO size of the tire. The best way to conclusively measure is to buy an ISO 635 tire and mount it on the rim. But if you can, do post a picture of the original tire. We can help steer you right.

verktyg 

This old Canadian/US Dunlop ad shows their tire offerings along with the rims that they fit.





In the 70's we had an old black bike on display. It may have been German made from the 1930's. It took some odd tires. They were ~30" with the tube sewn in like a tubular/sewup tire except they weren't glued on. We found a NOS set made by US Rubber Co. from the 40's. They had presta type valves. Back then, I didn't want to touch that refugee from the crusher...

verktyg

beng1

I took some photos of the old original tire, rear hub and rim today. Rim has a shallow cross section. Tire has no bead, but some odd flaps that overlap and a ridge that may have expanded to lock into the rim. Size says 28.1.7.

RustyJames 

Just guessing that the flaps are basically rim tape since the spokes are at the edges of the rim.

That tire could be VERY difficult to find but who knows?

RustyJames 

I’m not an expert on this stuff but all of ⬆️⬆️ makes a lot of sense. I too vote for the 635 size tire but getting it to work on the rim in question is likely an entirely different discussion.

If the OP was local I have a few 635 tires that could be experimented with.

scarlson 

The tires look like pretty standard clinchers to me. Those flaps are just an alternative to having rim tape. I feel like I've seen them on really old Dunlop tires. You can use normal rim tape and it'll work just fine with a normal tire! As for the ridge - I think that's the wire bead, if I'm not mistaken. Like any tire, really.
OK, good to know. What else does it say on it? I see "für felgen ..." but I would like to know what it says after that. Really any markings on the tire would be helpful. Für felgen just means "for rims" but it will probably say something after that - a specific type of rim, maybe, if we're lucky??

As for the rim itself, it really looks like a Westwood/chapeau-de-gendarme. Pretty standard stuff, but it would be nice to see the other side of the rim - the side the tire mates with - so we can see the bead seats and spoke nipple bed.

RustyJames 

As scarlson mentioned - ISO/ETRTO was established in 1970 so, if it were me, I would use “modern” sizing only as a reference point.

I love diving into this stuff which is probably why I end up with oddball bikes.

scarlson 

Huh, OK, so I found some more stuff out.

I started by searching for german sites with the search terms "28x1.70 Reifen". That brought me to this site:
https://www-radforum-de.translate.go..._x_tr_pto=wapp

Where a person with a '30s bike tries 622 (700c) which is too small, and 28 (presumably 635) which is too big. It's suggested to try 27" (630) but he hasn't tried it. I learned a new word there, though. "Wulstreifen" which means literally "beaded tire" but seems to be used in the context of bikes to mean your old style of tire with the flaps.

So I looked up "wulstreifen 28 x 1.70" and found some NSU forums! Jackpot!
But it's mostly just guys looking for tires, no real solutions.

However, I found this:
https://classic-cycle.com/search?sSearch=beaded+edge

https://classic-cycle.com/wheel-and-...res-28-x-1-1/2

These seem like the actual thing!

Maybe?

Unfortunately, shipping is about 80 EUR according to this page. You should probably email them, and they'd be experts and you'd be sure you were buying the right thing. STILL cheaper and easier than redoing the wheels to smaller rims.

If you did go the route of changing the rims, I'd get some Westwood style 635 or some aluminum 27" (630) rims. But I still wouldn't. It's a piece of history you've got there.