Author Topic: Seeking 26 inch rims/wheels, that are tubeless ready AND rim brake compatible  (Read 10877 times)

martinf

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Re: Seeking 26 inch rims/wheels, that are tubeless ready AND rim brake compatible
« Reply #30 on: September 29, 2023, 08:05:52 AM »

I do not know how well brake pads would work in smoothing out the joint compared to some careful work with a small file.

I am running Koolstop Salmon pads on most of my bikes, they are one of the softer pads.

Brake pads (or perhaps the grit they pick up) work quite well at smoothing out the joint. I only filed my Brompton rim because the step at the joint was big enough to annoy me.

I think it is rarely an issue with modern rims, if my memory is correct a small step at the joint on new rims was quite common in the late 1970's.

PH

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Re: Seeking 26 inch rims/wheels, that are tubeless ready AND rim brake compatible
« Reply #31 on: September 29, 2023, 10:09:55 AM »
I think it is rarely an issue with modern rims, if my memory is correct a small step at the joint on new rims was quite common in the late 1970's.
At that time and probably at least a decade later, nearly all rims would be pinned or sleeved.  Possible reasons for the change - Better aluminium alloys and welding, automated manufacture, perceived improvement... The last applies to all consumer goods, we want stuff that's perfect from day one rather than it requiring some running in.  I can't find the link but remember Jobst Brandt making the same point about machined rims, that it was only a benefit for the initial miles and a long term detriment.

Danneaux

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Re: Seeking 26 inch rims/wheels, that are tubeless ready AND rim brake compatible
« Reply #32 on: September 29, 2023, 04:13:08 PM »
As a data point, I align pinned aluminum rims in my vise, the jaws covered with my choice of rubber covered aluminum, plain aluminum, copper or brass.

It is pretty easy to create a smooth transition at the joint without the need to remove any metal.

My long beloved Mavic MA-2 rims in back-stock have all been nicely corrected this way, as have my older Araya 20A rims, also in back-stock.

So long as one doesn't over-compress the rim, it is a safe procedure and can be done gradually.

Best, Dan.

PH

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As a data point, I align pinned aluminum rims in my vise, the jaws covered with my choice of rubber covered aluminum, plain aluminum, copper or brass.
Best, Dan.
That's interesting Dan. Do you do that before building or after?  I don't think I've never built my own on pinned rims. A pair I supplied to a builder had quite a ridge when I took them and it had almost disappeared when he'd built them, I understood that happened as a natural consequence of the build.

Danneaux

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I realign the pinned rims before a build, Paul, though just as you say, spoke tension as the wheel is built does draw the rim ends together compressively...though not always laterally, or enough to my liking.

Pinned rims are so rare these days, I feel like a dinosaur for proffering the vise tip, but it worked nicely for me. Not so well for a friend who was ham-handed with the vise and left a depression on either side - oops!

Back in the day, I re-rolled a Mavic MA-2 from 700C down to 26in, 36 holes down to either a 28 to 32 (I forget now) for a bike with mixed wheel sizes. Spacing was pretty close between spoke holes as I recall. I wasn't the first to do so; as I recall Keith Bontrager and others did the same back in the day. I used a 3/4in thick round plywood buck (form) and clamps to get the ends close close and milled an aluminum slug for the rim hollow and secured it with epoxy. I remember others doing this when they wanted narrow box-section rims for their fat-tired MTBs (a whole topic in itself!*) and none were available and it seems to me they did not secure the rim internally, which made me uneasy. I don't recall any coming apart, but I could envision the raw ends slipping past each other if the wheel taco'd and it wasn't appealing.

By the way, the MA-2 was polished and a terrific rim with no problems except the occasional offset in the braking track, hence my squeezing. The MA-40 was identical in design and side but dark anodized and subject to cracking 'round the spoke holes because the rim ferrules clinched through the hard anodizing, making for stress risers in the substrate and it all went bad from there under tension and use. People wanted them 'cos the pros raced on them and the charcoal color made for a new and exotic look. As often happens, fashion drove the bus in this case. These rims were double-ferruled, which was thougth to distribute high spoke tension across both the inner and outer rim walls of the box section. In practice, the inner ferrule took the lion's share of the strain and the separate portion spanning the two walls didn't do much due to manufacturing tolerance and variance in clinching pressure.

Best, Dan. (...who enjoys the occasional trip down Memory Lane)
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*A separate addendum to hopefully avoid diluting the main topic and thread...

Fat MTB tires on really narrow rims was a "thing" on MTBs for a time back in the 1980s. Bruce Gordon lived and built frames in my hometown of Eugene for awhile -- twice, in fact, as he first lived out by the airport, then relocated to California, then returned to Eugene off Blair Street and then finally moved everything to Petaluma for good. I invited him to speak at the touring class I taught and though at first reluctant, shy (he was in those days!) he was wholly pleasant and accommodating wound up enjoying himself so much he spent three hours with the class! A few class member later signed up for the framebuilding classes he offered for awhile out of his home shop here. He brought several of his own bikes that evening and everyone was amazed at how large they were, a match to his tall physique. He also did some fork crown machining and head tube milling on a couple of my Japanese-made frames so I could fit European-standard headsets, including one of the first in the modern era with roller bearings, an Italian Galli Supercriterium, which unlike their Criterim group, included a small titanium insert.

Mavic MA-2 rims were a favorite of Bruce's and I believe he used them to mount early versions of his "Rock 'n' Road" fat 700C tires (maybe the first modern "29er" gravel tire). In those days, in America, the touring market was heavily influenced by racing components and a lot of stuff we took for granted later was unavailable and tire sizes were wildly misstated in a marketing-driven effort to come in with the lightest weight-in-class tire. When we got wider tires,  they were often fitted to narrow rims by default. My Herse-style road tourer uses MA-2s (was originally factory-fitted with Araya 20A, a very similar rim with nearly identical dimensions) running 700x36C Panaracer Paselas and I've happily run 38s with no problem on the MA-2s used on my favorite randonneur bike. Never a problem with tire roll-off on that combo even during punctures and it has worked well. Only downside was having to deflate the tire to get the wheel in and out between the brake blocks on my brazed-on centerpull. I would never go with such a mismatch on an even wider tire, as the jacking forces can be enough to split a rim if the too-wide tire is overpressurized.

martinf

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By the way, the MA-2 was polished and a terrific rim with no problems except the occasional offset in the braking track, hence my squeezing. The MA-40 was identical in design and side but dark anodized and subject to cracking 'round the spoke holes because the rim ferrules clinched through the hard anodizing, making for stress risers in the substrate and it all went bad from there under tension and use.

I've had MA-2 and MA-40 in the past, they are all gone now. The advantage of the MA-40 was that it was less affected by salt corrosion, at least cosmetically.

Also the contemporary but wider MA-3. I've still got 3 of those in service in 650B and 700C sizes.

And finally the even wider MA-4. I have had quite a few of these in 650B and 700C, they were my favourite rim for tandem use and loaded touring before I moved to the 26"/559 size and even wider tyres. I sold the last MA-4 as a complete wheel a couple of weeks ago.