masi61

I’m just thinking about how I want to build up a Puch Marco Polo I’m getting. It takes 27” wheels. I will check but 700c rims might be too low to allow the nutted centerpull brake calipers room to drop the brake pads down far enough. If I have to use the Sun CR-18 27” rims I have in my parts stash then this is what I will do as I have a nice 126mm 7-speed hub set built up into these rims.

But maybe someone could school me (again) about “ERD” - is it effective rim diameter? And how does a 27” rim compare with say, a 27.5 or 29er rim?. I’ve had so much learning, drama, some agony & (eventually) bliss from setting up my 2 “fast” road bikes full tubeless that I am ready to get even more creative fitting a tubeless option to an old school “touring” bike. If there was such a thing as a TLR 27” tire that natively fit old school 27” rims like a Super Champion 58 then that is what I would build. Problem is, I don’t think any of the still made 27” tire options are for tubeless operation. That would be cool though if one were to exist.

I also have seen the brake pad extenders that Bdop Cycling sells. These allow rim brakes to be dropped like an extra 10mm. I like this option for fitting 700c wheels onto frames designed for 27” more than filing the bottom hole on the caliper arms to gain more southern clearance. I obtained some cool Zeus nutted centerpulls NOS that I plan to use in place of the Puch’s standard Weinmann centerpulls.

bikemig 

The nutted center pull brakes on your Puch likely have the reach for 700c wheels and it they do not, you can always use a small round file to take a bit of material out from the slotted part of the brake arm. I had to do that on a Raleigh Gran Sport I recently built with 700c wheels. If you're OK with clincher, it sounds like you have good quality 27 inch rims in your stash and I'd be tempted to use those rather than go through the expense of sourcing 700c wheels.

John D

ISO rim diameters:
650b and 27.5 = 584mm
700c and 29" = 622mm
27" == 630mm
So the radius of a 700c from hub center to rim is only 4mm less than 27".

madpogue 

Unless there's something I'm unaware of, "tubeless" does not refer just to the tire. The rim has to be designed to allow the airtight seal of a tubeless tire. Old-school 27" rims were never imagined to be used with tubeless tires. So it's a matter of design, not just size.

repechage

Zeus centerpull calipers are on the small side, you may or may not get them to work.

I know of no brand of 630 mm tire that is Designed for tubeless. Might be like those early mtb tubeless adopters where lots of Stan’s is needed for marginal effectiveness.

masi61

This sort of answers my question - about 29” & 27.5”. I will probably stick with 27” rims then.

I get this. I wanted a “tubeless ready” rim to run full tubeless on this bike. I will have to test some 700c 126mm wheels on this Puch Marco Polo & mock up the Zeus 2000 centerpulls to evaluate cleanaces.

squirtdad

Pretty sure they don't make tubeless for 27 in rims you need to be a 700c (tried to find 27 tubeless at bike tires direct.... no luck)

TC1

Nitpick, but the rims don't need to be designed for tubeless as long as they are of reasonably high quality. There's a technique often called "ghetto tubeless" where one applies tubeless rim tape to a standard non-tubeless wheel, and this will often succeed if both the wheels and tires are of sufficient quality.

In fact, Stan's even makes a kit precisely for ghetto-izing non-tubeless rims.

https://mikesbikes.com/products/no-tube-rim-strip

None of that applies to a 27" setup, however, because none of the tires are tubeless-capable. You could maybe get one to seat on the rim, but it wouldn't be safe or smart to ride.

nlerner

^ I was also thinking that "ghetto tubeless" could be tried on just about any hooked-bead rim, but there aren't any 27" tubeless-compatible tires, i.e., what TC1 said.

squirtdad

IIRC the OP has gone the "ghetto" tubeless way before and had a lot of "fun"

masi61

No, I never went “Ghetto” tubeless before, just conventional road tubeless installations where I have 2 layers of tubeless tape, the correct tubeless valves & 23, 25 or 28mm full tubeless tires (from Panaracer or Hutchinson) mounted using an Airshot canister with ~140psi. Once the square beads lock into the compatible rim interior with their satisfying pop, pop, POP I then add the latex sealant, spin the wheel, wash off any stray sealant that escaped, then pressurize to final pressures. I love it that I can put 69 or 70 psi into a front 25 mm tire & 78 or 80 in the rear for my body weight (varies between 185 & 205 depending on what part of the riding season it is). Even natively full tubeless setups still can be a pain to mount or just will fail to hold pressure over night. I’m much better now & understand & have practiced what I am doing so my results currently are encouragingly good!

squirtdad

super, clearly my recollection was not correct

TC1

Also, since no one answered this question; ignore effective rim diameter completely. ERD is a specification for wheel builders -- specifically, it is the distance across the rim between points where spoke nipples engage with the rim. ERD is irrelevant to persons shopping for complete wheels. It is required only to determine the length of spokes necessary to assemble the wheel.

ISO diameter is the number one cares about if buying complete wheels, not ERD. The ERD of a wheel varies by the design and depth of the rim, so a deep aero 700c (ISO 622) rim might have an ERD of only 520mm, while a shallow traditional 700c (still 622 ISO) rim might be 600mm ERD. The same tires fit on both, obviously.

repechage

Super champion Gentleman rims come in 27” and hook bead cross section. I have a set.

Could it be made to work? Feeling lucky today, tomorrow and the next?

rustystrings61 

What vintage is your Marco Polo? I'm somewhat familiar with the early versions (531 db main frame, Puch 482 nickel-carbon forks and stays), and if memory serves the geometry is pretty much identical with that of my '76 Royal X, which was the next model up in '76. FWIW, my Royal X came stock with 27-in Weinmann rims, and I know I ran it successfully with full-size 27 x 1 1/4 tires AND Bluemels mudguards; later I ran it for many years with 700C-sized tubulars, merely moving the pads down a few mm all around on the Weinmann Carrera sidepulls that came stock on that model.

I supposed you could find a way to run it tubeless, but honestly - basic Panaracer Pasela's in 1 1/4 width, steel beads and all, at 65-70 psi, even with tubes, are shockingly smooth and fast on all sorts of road surfaces. Those pressures, btw, were the stock pressure pretty much everyone used with clincher 27s until the arrival of hooked bead rims and the Michelin Elan - and I still spit when I say that name. No need to go tubeless at those pressures ... unless you really, really want to.

79pmooney

If the OP wanted to go to 700c and the brakes don't reach, drop bolts could be used. (A fitting that goes into the bike frame's brake bolt holes and that you attach the brake to a little lower down. I've never used one and haven't seen one in a long time (when it really didn't matter to me) so I cannot give you any details. Just that they do exist and can be made and allow short reach brakes to reach low rims or longer reach brakes to reach at shorter and more powerful brake pad locations.

A Duck-Duck or Google might turn up a source or at least a picture.

masi61

The Marco Polo I want to says is from around 1977 or 78. It is black with a red HED tube and painted red on the back part lf the rear triangle. I have a set of nutted, long reach Tektro dual pivot side pulls that I bought for just such a project that I have never used. Maybe I will ditch the idea of utilizing the Zeus 2000 centerpulls in favor of the long reach Tektros.

rustystrings61 

Like the one in this catalog? Really well-built frames made in Graz, nicely mitered, and silver-brazed, even. The ride quality will probably be indistinguishable from the best of the Puch/Austro-Daimler bikes (apart from the Ultima and Superleicht). Are you SURE the Weinmanns won't work? Weinmann Vainquer 999 centerpulls with modern stainless cables, lined housings, and good brake pads are amazing - and if you run some Tektro aero levers you will be delighted at how well they work. I have that set up on this bike, and it's awesome -

masi61

rustystrings61 - YES that’s the one. I already have one BTW that has been repainted with braze-on shifter mounts, top tube cable guides & (I believe) water bottle cage mounts added. AFAIK - The Weinmann’s would work fine. I just happen to have a set of the Zeus that I thought would be cool to try.

Here is the completed auction for the “new” Marco Polo BTW. I’m hoping the frame is more like a 23” instead of the (too big) 25” one that was my main steed for over 20 years.

https://www.ebay.com/itm/29594376597...mis&media=COPY

masi61

Since 29er’s have an ISO of 622 just like 700c, does anyone know if there is any such thing as a 29er rim with machined sidewalls for rim brakes?

Also, just curiuusL what does “ISO” stand for anyway?

panzerwagon 

International Standards Organization? Commonly used method of specifying rim diameter.

There are also different ISO and JIS headset standards— the latter originating in Japan.

DiegoFrogs

Looking at where the brake pads are in the listing, I'd be shocked if it didn't work just fine with 700c rims and those calipers. I've never had problems with OEM centerpull or sidepull calipers in a 70s or 80s conversion from 27" to 700c.

TC1

There isn't really any such thing as a "29er" rim. It's just a marketing term for a (typically wide) 700c.

That said, yes, rim brake rims marketed as "29ers" exist -- for example, DT Swiss' TK 540 29 18.2 MM RB VI (what a name ).

Johno59

You can get brake pads that step down to accommodate. modern rims on older frames. Also as mentioned above you can purchase or fabricate an extension that lowers the entire caliper so the normal pads can reach the lower 700c braking surface.
Elongating the slot on existing calipers is living dangerously as Al work hardens and thus becomes brittle once it's been filed..

Kontact 

700c wheels on 27" bike = extra large tires.