I can get a single pivot caliper deep enough, but the performance is inadequate. Does anyone know of a dual pivot caliper that's at least 90mm deep? Or another solution? It's for the front of a cargo bike where a disc brake or roller brake is not possible. I've done a lot of Google searches without result. Thanks.
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Some of the vintage center-mount center-pull brakes will reach that far and have better stopping power than side-pull single pivot calipers. But I agree with the answer below that your best bet is to get someone to braze on some cantilever brake posts and use those. I'm assuming that using a larger wheel or a different fork to shorten the reach is not an option?– AndrewCommented Jan 23, 2020 at 22:02
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Why is a disk brake not possible? Given the mass of a cargo bike and its load, perhaps a disk brake and a rim brake would be the ultimate, along with a rear brake too.– Criggie ♦Commented Jan 23, 2020 at 23:36
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1Some photos of your fork and front wheel might complement the question, inspiring additional answers with alternative solutions.– Criggie ♦Commented Jan 23, 2020 at 23:37
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3 Answers
Even a dual-pivot brake probably isn't going to solve the problem you found with a single-pivot brake: after a certain point, those long brake arms are flexing and absorbing the energy you're trying to put into the pads. This is why you generally don't see caliper brakes on fat-tire bikes. I did a quick check, and even Tektro's long-reach calipers aren't long enough for your application.
Cantilever brakes would be the more orthodox solution to this problem. They're widely available and a known quantity.
answered Jan 23, 2020 at 16:35
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If you don't know anyone who can braze on canti mounting posts for you, you can use these clamp on posts: universalcycles.com/shopping/…– AndrewCommented Jan 23, 2020 at 22:03
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@Andrew Would be good to highlight "ONLY for Identiti Rebate forks, not for use with any other product, bike, science project or garage creation " so no, those will not suit a random bike.– Criggie ♦Commented Jan 23, 2020 at 23:25
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@criggie That’s just a liability disclaimer. The “only” fork they will work on is a basic rigid butted chromoly. I wouldn’t put them on an unreinforced carbon fork, but I’m fairly confident they’d be fine on any fork that’s on a cargo bike.– AndrewCommented Jan 24, 2020 at 3:51
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@Andrew I figured the adapter mates with some kind of flat on the approved fork. What stops them pressing/rotating inboard when the brakes are applied? Feel free to put the answer into your answer to avoid this becoming a conversation thread in comments :)– Criggie ♦Commented Jan 24, 2020 at 7:39
Thanks for all the input and advice.
I've found an Alhonga U brake sold as suitable for folding bikes, it is a self contained centre pull almost like a Delta brake, in alloy with 110 mm max drop. Not easy to find a Google image of it, but here's a link https://www.bicyclepartswholesale.com.au/product/4459-brake-alhonga-front-brake-arm-alloy-for-folding-bikes-drop-110mm .
That's what I'm going with, I'll let the forum know how it works.
Another possible is a 91mm deep Altenburger/Point/Alhonga Synchron which is an early design dual pivot. Reputation for being very flexible , possibly little better than many single pivots.
I could buy a new fork with disc mounts but it's very expensive. I can't readily get any fork mods done around here, frame builders are rather thin on the ground here in Western Australia :(
Henry - I ended up using a long reach brake caliper and had to create a lower mount point for it.
For me, this was caused by changing from 27" (630mm) wheels down to 700c (622mm) wheel.
So I made a dropper plate to provide a lower mounting point. In theory I should have used two plates, one in front and one behind the brake bridge.
Steel would have been a better material than aluminium as pictured, but it was thick and its what I had.
Also, its a rear wheel so there are far lower peaks in braking effort on this end of the bike.
The pictured calipers are Tektro R559, and even with my mount plate, they only just reached the rims.
Personally, for a front wheel, I'd recommend you find a better fork with disk mounts, and a wheel with a brake rotor.
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1Short term proof of concept I would be happy enough. Long term I would be concerned about that plate, being aluminum, fatiguing. Add regular inspections for cracks to your maintenance list.– mattnzCommented Jan 27, 2020 at 7:06
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@mattnz quite right - that bike only lasted a year and has long since been retired. That pictured rear wheel kept breaking expensive weird shimano spokes, and was seriously scalloped. A replacement wheelset had different characteristics, and the whole frame shimmied terrifyingly bad on a downhill. I think resonance with the straightened seat stay was a significant factor. But for a junk bike I did 3000 km, including some decent "gravel" rides.– Criggie ♦Commented Jan 27, 2020 at 9:44