Thorn Cycles Forum
Technical => Wheels, Tyres and Brakes => Topic started by: Dunroving on September 13, 2023, 05:12:48 PM
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Looking for the above (in the UK) and drawing a complete blank. I have been unable to either (a) locate a set of 32h rims in order to build a set of wheels, or (b) even find an already-built set of wheels that are tubeless and rim brake compatible. I find either they are rim brake compatible but not tubeless ready/tubeless compatible or they are tubeless ready/tubeless compatible but not rim brake compatible.
Have already tried hacking a tubeless set-up on the current rims and it's not sufficiently reliable. Can anyone suggest a source of such wheels, or know of a wheel/rim make and model that meets the above needs?
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Tubeless tires became popular for a generation that had already moved from rim brakes to disc brakes. And high-end rim-brake rims in general are slowly being discontinued by manufacturers. I wouldn’t be surprised if what you are looking for simply doesn’t exist.
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I had a look at the Ryde manufacturer's website, 5 rims in their catalogue for 26" (559) and rim brakes but none are tubeless compatible.
So I reckon WorldTourer is probably right and the rim brake/tubeless combination either doesn't exist in 26" or is extremely rare and difficult to find.
Even in the now more popular 700C (622) size there is only one Ryde rim that is both rim brake and tubeless ready - the Edge R 25 os.
And nothing with the rim brake/tubeless combination in their catalogue for the revived 650B (now called 27.5") 584 size
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Do you get many punctures? I run tubeless on my MTB, but ride daily on a mixture of roads and bridleways on traditional tyres and inner tubes and rarely get any flats. Maybe I'm lucky? Mostly use Panaracer Tourguards and lighter Continental Speed Contacts for all but winter duties.
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Previous thread with a couple of suggestions
http://thorncyclesforum.co.uk/index.php?topic=14646.msg111869#msg111869
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Thanks for the replies so far, everyone. Just some brief replies to some of your comments:
(1) Yes, I had begun to realise that my needs fall into whatever is the opposite of a "sweet spot," due to the timing of changes in technology (towards disc brakes, away from 26", and towards tubeless).
(2) Thanks for the link to the old thread, PH. I had search for tubeless in the forum, but the thread title of that thread hadn't pulled me towards it.
(3) The main thing drawing me towards tubeless is that for the first time a year ago, I switched to tubeless on another bike and have lost count of the number of times I've been with groups who have had to stop for punctures and I've not had to has really impressed me. But I've managed to get through several decades fixing punctures in inner tubes that it won't kill me if I don't find anything.
(4) I followed the link in the older thread to the Velocity Cliffhangers, but it looks at the moment like they no loner sell rim brake compatible in 26". I've emailed them and will post what I find.
(5) Have found one wheelset that looks like it may work - disc brake compatible, but with a machined rim that will accept rim brakes. It's a set of Pro-Lite Sport MD-10s, built in Taiwan. They are pretty inexpensive (< £150 for a set), which makes me wonder about the quality, but I'm looking into it further.
Will post updates and eventual outcome for anyone who finds this thread at a later date.
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Thanks for the replies so far, everyone. Just some brief replies to some of your comments:
(1) Yes, I had begun to realise that my needs fall into whatever is the opposite of a "sweet spot," due to the timing of changes in technology (towards disc brakes, away from 26", and towards tubeless).
(2) Thanks for the link to the old thread, PH. I had search for tubeless in the forum, but the thread title of that thread hadn't pulled me towards it.
(3) The main thing drawing me towards tubeless is that for the first time a year ago, I switched to tubeless on another bike and have lost count of the number of times I've been with groups who have had to stop for punctures and I've not had to has really impressed me. But I've managed to get through several decades fixing punctures in inner tubes that it won't kill me if I don't find anything.
(4) I followed the link in the older thread to the Velocity Cliffhangers, but it looks at the moment like they no loner sell rim brake compatible in 26". I've emailed them and will post what I find.
(5) Have found one wheelset that looks like it may work - disc brake compatible, but with a machined rim that will accept rim brakes. It's a set of Pro-Lite Sport MD-10s, built in Taiwan. They are pretty inexpensive (< £150 for a set), which makes me wonder about the quality, but I'm looking into it further.
Will post updates and eventual outcome for anyone who finds this thread at a later date.
Update: I just received an interesting reply from one retailer: "I do have some cliff hanger 'disc' rims in stock. They are actually the same rim but without machining on the braking surface. So while the braking from new isn't as effective, you can brake on them and over time they end up with the same performance anyway"
Perhaps I am misunderstanding, but I thought that disc brake compatible rims were thinner and that is why they are unsuitable for rim brakes?
- have also checked the Velocity US Web site, and it looks like they do make what I'm looking for, but I just need to find a UK retailer that has them!
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Perhaps I am misunderstanding, but I thought that disc brake compatible rims were thinner and that is why they are unsuitable for rim brakes?
- have also checked the Velocity US Web site, and it looks like they do make what I'm looking for, but I just need to find a UK retailer that has them!
I think Velocity rims that are disc only are only painted, not machined. I have machined rims on my Lynskey for rim brakes. As far as I know, their disc brake rims that are the same models as rim brake rims would have thicker rim sidewalls on the disc version. Not sure if I am clear here, my Lynskey has Velocity Dyad rims, they are machined for rim brake use, but they also sell Dyad rims that are not machined for disc use, and the disc version should have thick sides on them for a braking surface. (The Dyad is a tube type rim.) Their A23 is a tubeless type, but that might be for a narrower tire than you want.
https://www.velocityusa.com/product/rims/a23-559
https://www.velocityusa.com/tech/rims/
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Perhaps I am misunderstanding, but I thought that disc brake compatible rims were thinner and that is why they are unsuitable for rim brakes?
- have also checked the Velocity US Web site, and it looks like they do make what I'm looking for, but I just need to find a UK retailer that has them!
I think Velocity rims that are disc only are only painted, not machined. I have machined rims on my Lynskey for rim brakes. As far as I know, their disc brake rims that are the same models as rim brake rims would have thicker rim sidewalls on the disc version. Not sure if I am clear here, my Lynskey has Velocity Dyad rims, they are machined for rim brake use, but they also sell Dyad rims that are not machined for disc use, and the disc version should have thick sides on them for a braking surface. (The Dyad is a tube type rim.) Their A23 is a tubeless type, but that might be for a narrower tire than you want.
https://www.velocityusa.com/product/rims/a23-559
https://www.velocityusa.com/tech/rims/
Interestingly, I came across two additional sources of information yesterday. First was a phone call from a wheel builder who I know from a mutual friend. He said he thought the "un-machined" Velocity Cliffhanger rims weren't flat enough to accommodate the brake pads comfortably (he's built wheels with the VC before).
Then I came across two YouTube videos of a tour of Velocity's factory - very interesting! In the second video, they discussed the machining process and, as you indicated, this does result in the rim brake rim being very slightly thinner - so the structure of the VC rim is the same regardless of whether they are intended for rim brake or disc brake wheels (which is quite different if memory serves, from many rims - where disc brake rims are thinner in order to achieve lighter weight). In the video, he described how you can brake using the anodised surface (disc brake rim), and it will eventually wear off. However, he described an additional benefit of using the machined rim - if there is any slight bump where the rim joint is located, this will cause increased pad wear, and a slight hiccup every time the pad goes over the rim joint. Interesting ...
Video is here: https://www.youtube.com/watch?v=Y56TgT6jd9A (https://www.youtube.com/watch?v=Y56TgT6jd9A) (section on machining the rim starts at about 23:23)
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so the structure of the VC rim is the same regardless of whether they are intended for rim brake or disc brake wheels (which is quite different if memory serves, from many rims - where disc brake rims are thinner in order to achieve lighter weight).
At one time the braking surface of all rims was un-machined, it was expected that you'd ride them smooth and they'd improve with use. Then manufacturers would offer a choice, some riders preferred perfect from day one, others hung onto the idea that they weren't going to pay more for less! Disc brake users could choose either. Until disc brakes became popular, it wasn't worthwhile creating new rims for them. Now it is and you'd expect a disc specific rim to be made from a unique extrusion. With no need for a brake track, you can build a rim that's both lighter and stronger, though in reality the differences might be overestimated.
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However, he described an additional benefit of using the machined rim - if there is any slight bump where the rim joint is located, this will cause increased pad wear, and a slight hiccup every time the pad goes over the rim joint.
I had a rim with a pronounced step at the joint, enough to be really annoying when braking.
I filed it more or less flat, and then let the brake pads finish the work.
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I mentioned above that my Lynskey has Velocity Dyad (tube type) rims, I built up that bike with rim brake front, disc rear, but for aesthetics I put a rim brake rim on both front and rear so the wheels would match. So, spent a few extra bucks for the machined rim in back where a disc is used.
I listed this link in a previous post:
https://www.velocityusa.com/tech/rims/
That listed the Cliffhanger rim as disc or rim brake, unlike some of their other rims that are disc only.
The Cliffhanger is available in a rim brake version.
https://www.velocityusa.com/product/rims/cliff-hanger-559
That is a pretty wide rim, but if you are mostly using 45 to 65mm tires, go for it.
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I mentioned above that my Lynskey has Velocity Dyad (tube type) rims, I built up that bike with rim brake front, disc rear, but for aesthetics I put a rim brake rim on both front and rear so the wheels would match. So, spent a few extra bucks for the machined rim in back where a disc is used.
I listed this link in a previous post:
https://www.velocityusa.com/tech/rims/
That listed the Cliffhanger rim as disc or rim brake, unlike some of their other rims that are disc only.
The Cliffhanger is available in a rim brake version.
https://www.velocityusa.com/product/rims/cliff-hanger-559
That is a pretty wide rim, but if you are mostly using 45 to 65mm tires, go for it.
Will be going with the Cliffhanger machined rim, 26", 32H - if I can get them! Velocity has offered to ship for me, which I considered for about one minute. For some odd reason, they are more expensive that way ($285 [£228] inc. shipping and handling - though presume possibly could also be hit with customs charges?) UK and EU suppliers are listing them at £130 for a pair, except I can't find any in stock so far. Brick Lane are their official UK distributor, but they checked the warehouse and couldn't find any.
Will be running 60C tyres.
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Will be going with the Cliffhanger machined rim, 26", 32H - if I can get them! Velocity has offered to ship for me, which I considered for about one minute. For some odd reason, they are more expensive that way ($285 [£228] inc. shipping and handling - though presume possibly could also be hit with customs charges?) UK and EU suppliers are listing them at £130 for a pair, except I can't find any in stock so far. Brick Lane are their official UK distributor, but they checked the warehouse and couldn't find any.
Will be running 60C tyres.
Maybe SJS should start selling Velocity rims?
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Tubeless ready = difficult to mount. The switch is market/bling driven. Oooh, but "autos use tubeless".... ugh! I am happy with Ryde Andra. Perhaps someone is riding off road in goathead thorn country. Yes, tubeless is then useful in that very specific region. When we ride in Arizona, tubes are fine, no punctures in 4 years, but we avoid off road and check for thorns.
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Tubeless ready = difficult to mount. The switch is market/bling driven. Oooh, but "autos use tubeless".... ugh! I am happy with Ryde Andra. Perhaps someone is riding off road in goathead thorn country. Yes, tubeless is then useful in that very specific region. When we ride in Arizona, tubes are fine, no punctures in 4 years, but we avoid off road and check for thorns.
Well, that’s the thing, you avoid off-road, but loads of people intentionally seek out off-road.
The Baja Divide is a route where tubeless is highly recommended, to put it mildly. The Baja Divide is now part of the Alaska–Ushuaia route for anyone looking to ride offroad as much as possible. So, it has become common for Alaska–Ushuaia or more generally North America – South America cyclists to install tubeless tires for their entire journey.
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I know several people that are migrating to tubeless for the wider tires that they use off road, but they are mostly staying with tubes for road and on-pavement (tarmac) riding with narrower tires.
I do not live in an area with a lot of thorns (the pointy kind, not the bikes), so I almost never get a puncture from a thorn. For me, broken glass or sharp steel is more likely to cause a puncture.
I average one puncture a year, and I ride several bikes during the year. So, for me the time spent fixing the puncture when it happens is preferred instead of maintaining sealant in several different bikes.
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I've been riding today with someone using tubeless on Halo White Line rims in 26". These are not designed as such, but he said it was simple enough to set them up and in a couple of years riding has had no issues, or punctures.
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Will be running 60C tyres.
One additional note: I assume you already know this, but if not, 60mm wide tires on a rim brake bike means that you will need either cantilever brakes or a V brake with an unusually long arm.
If my memory is correct, I used Tektro 857 AL for V brakes on two of my bikes, they have 110mm long arms.
Specifically, my Nomad Mk II, I use 57mm wide tires and also fenders. I needed long arms, otherwise the cable was rubbing on my fender with my other brakes that had shorter arms.
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One additional note: I assume you already know this, but if not, 60mm wide tires on a rim brake bike means that you will need either cantilever brakes or a V brake with an unusually long arm.
If my memory is correct, I used Tektro 857 AL for V brakes on two of my bikes, they have 110mm long arms.
Specifically, my Nomad Mk II, I use 57mm wide tires and also fenders. I needed long arms, otherwise the cable was rubbing on my fender with my other brakes that had shorter arms.
When I put 55 mm Marathon Mondials on my Thorn Raven "utility" bike I had to change the rear V-brake, but not the front.
The only long arm V-brake I could find at the time was an XLC brand with 110 mm arms, the Tektro 857 AL wasn't available anywhere I searched.
There was enough clearance to keep the Shimano Deore LX BR-T670 front brake (I think this has 103 mm long arms).
With a 60 mm tyre this would need to be changed as well, unless doing without mudguards.
Despite being fairly cheap, the XLC brake seems to work well enough after swapping out the standard brake pads for Kool-Stop salmon.
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Tubeless ready = difficult to mount. The switch is market/bling driven. Oooh, but "autos use tubeless".... ugh! I am happy with Ryde Andra. Perhaps someone is riding off road in goathead thorn country. Yes, tubeless is then useful in that very specific region. When we ride in Arizona, tubes are fine, no punctures in 4 years, but we avoid off road and check for thorns.
This will be largely for off-road use, so your observations are spot-on; tubeless means I don't have to worry about thorns during hedge-cutting season, or on canal towpaths with broken glass littered around (you probably don't get much of that in Arizona).
I've never really had difficulty mounting tubeless tyres (or any tyres, for that matter). Your experience trying to mount tubeless tyres may vary. Glad you're happy with your tubed tyres and rims (I still use tubes on my shopping bike, and have ridden tubes on the road with almost no punctures since the 1980s).
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I've never really had difficulty mounting tubeless tyres (or any tyres, for that matter). Your experience trying to mount tubeless tyres may vary. Glad you're happy with your tubed tyres and rims (I still use tubes on my shopping bike, and have ridden tubes on the road with almost no punctures since the 1980s).
I have only run tube type rims and always use inner tubes. But I did buy a tire that I did not realize was intended for tubeless, I had to really work hard to get the bead over the rim, it was so tight.
A couple months ago was out for an exercise ride, about an hour and a half, out and back trip. On my way out, saw a teenage kid trying to fix his tire. And on the way back stopped when I saw that he had made no progress. He had a tubeless rim, inner tube, and I am not sure if the tire was a tubeless tire or plain, I suspect tubeless. But he was not strong enough to get the tire off the rim. But in part he did not understand the shelf under the bead that is part of the tubeless rim design, so I had to show him how to get almost all of the bead in the depression in the rim before he could get the bead over the edge of the rim.
Part of the problem was that the bead sitting on the shelf took so much muscle to get it shifted into the depression, I think he did not have the hand strength to do that part of the fix.
It was a good reminder to me to be very careful to never buy another tire that was "tubeless ready" since I am sticking with tubes.
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Will be running 60C tyres.
One additional note: I assume you already know this, but if not, 60mm wide tires on a rim brake bike means that you will need either cantilever brakes or a V brake with an unusually long arm.
If my memory is correct, I used Tektro 857 AL for V brakes on two of my bikes, they have 110mm long arms.
Specifically, my Nomad Mk II, I use 57mm wide tires and also fenders. I needed long arms, otherwise the cable was rubbing on my fender with my other brakes that had shorter arms.
That's interesting - I currently have 2.2" tyres (tubed) on the bike without any issues from the V-brakes ... they're Shimano but can't recall which model (bike isn't with me to check at the moment). Possibly Deore.
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That's interesting - I currently have 2.2" tyres (tubed) on the bike without any issues from the V-brakes
In some way you're not comparing like with like. Thorn 26" wheel touring bikes have the brakes set with the block at the bottom of the slot, but they were also designed at a time when almost no one would have considered touring on a 2.2" tyre.
I might have just squeezed a 2" tyre into my Raven, though it wouldn't have left what I'd consider a satisfactory clearance under the guards and I might have had to deflate the tyre to remove it.
From what I can tell from the brochure, the current Nomad with 26" wheels, will take 2.15" tyres with V brakes or 2.5" with discs. I'm assuming both those figures include good guard clearance.
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From what I can tell from the brochure, the current Nomad with 26" wheels, will take 2.15" tyres with V brakes or 2.5" with discs. I'm assuming both those figures include good guard clearance.
The Nomad Mk3 with disc brakes and the Thorn Bikepacking Fork option will easily fit 2.60" tires (without mudguards, I guess, but didn’t try) with 650B wheels. So, 26" wheelsize users with disc brakes would definitely be able to fit at least 2.60" width as well.
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From what I can tell from the brochure, the current Nomad with 26" wheels, will take 2.15" tyres with V brakes or 2.5" with discs. I'm assuming both those figures include good guard clearance.
The Nomad Mk3 with disc brakes and the Thorn Bikepacking Fork option will easily fit 2.60" tires (without mudguards, I guess, but didn’t try) with 650B wheels. So, 26" wheelsize users with disc brakes would definitely be able to fit at least 2.60" width as well.
Out of curiosity, I've just had a glance at the SJS website which offers more detail than the Thorn Nomad brochure
26" V brake fork 2.35" with guards
26"/650B/700c twin plate disc fork with 26" wheel 2.8" with guards
26"/650B/700c Bike Packing fork with 26" wheel 2.75", but doesn't say if that's with guards
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Brief update: After a fair bit of research, I've sourced some Velocity Cliffhanger rims and will pair to Bitex 103 touring hubs. These hubs get decent reviews and a couple of good YouTube videos. I also looked at Shimano Deore T610 and M610 hubs (no longer made, but can be found with a lot of searching), but the Bitex were a step up, and not horrendously spendy.
I ended up only being able to get the disc brake Cliffhanger rims, but as mentioned here and in a couple of other threads, these can be used with rim brakes. I did notice the join on the rim wasn't especially smooth, so might need to sand down a bit.
Another option that I found was Kinlin XM-25, but these rims are a bit narrower (21 mm internal width) compared to the Cliffhangers (25 mm internal width) and so probably not best suited to the wider tyres I'm using. The Kinlin rims were a fair bit lighter, so would be more suited to anyone looking for something similar, but for narrower touring tyres.
I'll post another update when the wheels are built, and again after I've ridden them a couple of times.
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I did notice the join on the rim wasn't especially smooth, so might need to sand down a bit.
Are the joins pinned or welded? If pinned, you may find the step reduces under spoke tension, but also ask your wheelbuilder to make sure they step down, that is the brake block doesn't hit the ridge. Your builder almost certainly knows to do this, but I'd rather look an idiot than regret not mentioning it! If they're welded, then you can sand them down or wait for the blocks to do it for you.
I might ne tempted to find some hard blocks to wear the rims in, I don't know if those intended for carbide rims would be OK, though that's an expensive experiment. There's other hard compounds that I'd normally avoid which might be ideal for this purpose.
Bitex 103 touring hubs. These hubs get decent reviews and a couple of good YouTube videos. I also looked at Shimano Deore T610 and M610 hubs (no longer made, but can be found with a lot of searching), but the Bitex were a step up, and not horrendously spendy.
They have gained a good reputation, all those sealed bearings! I must admit I have a natural preference for cup and cone, partly the satisfaction of adjusting them to perfection. Shimano always wins on the shells, forged are stronger than machined and no one else makes in the quantity to warrent forging.
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I did notice the join on the rim wasn't especially smooth, so might need to sand down a bit.
Are the joins pinned or welded? If pinned, you may find the step reduces under spoke tension, but also ask your wheelbuilder to make sure they step down, that is the brake block doesn't hit the ridge. Your builder almost certainly knows to do this, but I'd rather look an idiot than regret not mentioning it! If they're welded, then you can sand them down or wait for the blocks to do it for you.
I might ne tempted to find some hard blocks to wear the rims in, I don't know if those intended for carbide rims would be OK, though that's an expensive experiment. There's other hard compounds that I'd normally avoid which might be ideal for this purpose.
Bitex 103 touring hubs. These hubs get decent reviews and a couple of good YouTube videos. I also looked at Shimano Deore T610 and M610 hubs (no longer made, but can be found with a lot of searching), but the Bitex were a step up, and not horrendously spendy.
They have gained a good reputation, all those sealed bearings! I must admit I have a natural preference for cup and cone, partly the satisfaction of adjusting them to perfection. Shimano always wins on the shells, forged are stronger than machined and no one else makes in the quantity to warrent forging.
From the YouTube video of the factory (link in my previous post; see about 15:00 onwards), they fit a sleeve inside where the join is (sleeve looks to be about 2 inches long), and coat it with an epoxy. The joined section is then baked for about 35 minutes, after which the join is (quote) "hard as a rock". Interestingly, he says the sleeve ensures there is no bump at the join to cause a "tick, tick" and "chew your brake pads". However, later in the video, where he describes the machining process, he says (around the 24:15 mark) this also "cleans up the join, so when your brakes run by it, there's no hiccup".
Point noted regarding getting harder brake pads to aid the smoothing process. I'll look into that.
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Point noted regarding getting harder brake pads to aid the smoothing process. I'll look into that.
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.
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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.
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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.
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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.
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.
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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.
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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.
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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.