Someone built me a small, custom recumbent bike recycled from older bike frames. He did a generally decent job, but seems to have messed up placing the rear canti studs. They should have been spaced inward toward the rim at least 5mm per side. At least, that's the estimate I get doing some measuring and initial setup. Where there's only about 4mm of pull left there (pads are contacting the rims at that point) there should be about 40-45mm between the noodle end and the right lever -- according to tektro's directions.

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I had first hoped to solve this problem by finding longer threaded post brake shoes. No one seems to market anything like that as a feature. The posts on these are 25mm, which look about the same as any others I've had in the past. I found nothing longer.

Next, I tried to approach this with a pair of female-male m6 spacer on each side, but I can't get enough male threaded post to install correctly.

My other potential option is (not my fave) canti brakes since he did put a canti stop bridge up top, just out of the photo. However, I'm not sure I won't have similar issues with the spacing, depending on post length. It appears that if I use a smooth post canti, like an altus, I might be able to get the far enough inward, since they secure by a loop pulling on them perpendicular to the direction of the post. (Probably should have gone for the canti brake first -- cheaper than the spacers were!)

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But not knowing the length of those posts (anyone?) I wasn't sure they'd solve the problem, and I wanted to avoid having to buy new brake levers as well, plus match the front brake to the back. (On this bike, the front doesn't carry much weight, so it should really have a weaker brake than the back to avoid locking up and washing out...)

The final option that I brainstormed was to use some 5mm or 7mm thick by 20mm wide aluminum stock and build a short adapter that attaches to the inside of the brake arms (toward the rim, thus providing the inward spacing) and secures with an M6 screw to the brake arms where the shoe normally mounts. Offset about 8mm to the side (opposite, across the arm center point, for max rigidity) a 6mm hole to mount the brake shoe as normal, with the beveled spacers for making angular contact. Up/down would be accomplished with the normal slot.

That would give me the spacing and the pieces are thick and short enough that they shouldn't flex much. It's a couple hours work with hand tools, I guess.

Adding sketch. The stock I've got is good quality, pretty stiff, and mounting as shown in the sketch actually places the shoe post a similar distance from the middle of the lever arm as the stock mounting slot, and the flats of the middle of the arm are pushing the adapter toward the rim too. Second photo shows midline of the brake arm better than my sketch.

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Anyone ever run into a similar issue? Anyone know of longer threaded post shoes or happen to know what the post length is for smooth post canti shoes?

Builder is willing to take it back, redo the rear end, which would mean re powder-coating as well, plus two trips shipping across the country. He won't charge for the fix of course, but it seems like a lot of effort and material, so I'd like to explore less resource-intensive options first.

Failing longer studs, taking any and all ideas!

  • 1
    I'd be very wary of home made spacers on brakes, but your idea seems sound. Perhaps if you pursue this idea you should draw it up first so we can have a proper look at the failure modes
    – Chris H
    Feb 13, 2018 at 12:58
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    It is a nice paint job, and it would be re-done just as nicely, but unless absolutely necessary, I don't want to soak the builder with the time and cost of substantial re-doing for this one-off project.
    – user36575
    Feb 13, 2018 at 13:49
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    Roger the threadlocker. I use it on everything on bikes -- unless they've got a nylock on the other end of the bolt. It's amazing how quickly stuff rattles apart. I had considered nylock and through-hole for the M6, but that complicates adjustment by requiring a third (fourth?) hand. If I try threaded first, I can always drill out for through-bolt and locknut after.
    – user36575
    Feb 13, 2018 at 14:38
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    It looks from your first picture like it would just work as is . Clearly you haven't finished building the bike yet but do you have a feel for it? Perhaps with an extra washer on the back of the pad you'd get enough reach, at least with new pads. Also that might be a good idea at first on one brake if you're modding the other, rather than risk a common failure mode on both wheels.
    – Chris H
    Feb 13, 2018 at 20:45
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    I roughed out the extension/spacers from .25" x 1" 6061 T6. I just dimensioned them freehand from the brake arms, placing the nut stacks where they'd need to be. They're about 1.25" long, with only about 1/2" overhang to the side. This aluminum is thicker than the original post slots. It's absolutely stiff -- I'd wager stiffer than the brake arm at that point. Only potential failure, I think, will be the m6 coming loose, but Loctite + a lock washer should take care of that. Once I get them prettied up I'll install.
    – user36575
    Feb 14, 2018 at 1:13

4 Answers 4


A rear wheel with a wider rim could make up the gap, depending on what you have in there now. There are a wider selection of wide rims available now, although I do not know if this extends to smaller wheel sizes. Wider rims will likely mean running a larger volume tire, but there is plenty of room.


Fwiw the closest thing there is to a standard is 80mm post to post. Comparing that number to what you're working with may be helpful. Rim width does of course have an impact; 75mm is supposedly a better number if it's known that road rims will be all that's used.

The genre of brake that I think would work the best are traditional wide-profile, long-armed, smooth-post cantis ala Mafac and similar. The reason I say that is the mechanical advantage characteristics of that type of brake get screwed up the least when the starting position of the arms is splayed in from the more intended starting point. If you can make a low profile canti like an Altus work without running into that issue, then fine, but it's going to depend on what the post to post distance is.

There are v-brakes, mostly early and/or cheap ones, that use smooth posts. They might buy you some millimeters but I don't know that you'd be able to get them so extended as to solve this.

Edit: Depending on what width rim you've got now, going with a wider rim could help the situation, although judging by the picture I doubt it would solve it all by itself. Sun Rhynolites are cheap and make good rear recumbent wheels by their own right.

  • I've got early v-brakes of the type you mention in your penultimate paragraph (canti pads). I'll try to have a look at them tonight. But they're cheap and nasty, on a BSO from about 15 years ago.
    – Chris H
    Feb 13, 2018 at 8:06
  • I'd considered building another wheel on a ryno, but it only gets me 2.5mm per side from this one (a CR-18). Better than nothing, but not quite there. I'll look for some longer-arm cantis for options.
    – user36575
    Feb 13, 2018 at 13:39
  • I measured post to post (centers) and got 95mm, which squares with 75 being a good distance, and my estimate that I need 7-8mm on each side.
    – user36575
    Feb 14, 2018 at 1:03
  • @WPNovicecoder it also occurred to me you may just be able to use the center mount version of the Paul Racer brake, or similar latter-day centerpulls. You'd need to measure the drop from the bridge to see. They're really good brakes so it may be the least compromised solution. I'm worried that if you jump through any of the sets of hoops that get you pads extended far enough to solve this with the posts where they are, you may have unmanageable brake squeal. Feb 14, 2018 at 5:48
  • I was worried about that too!
    – user36575
    Feb 17, 2018 at 20:34

Thanks for tall the input, folks. I made spacers and they do the job of moving the brakes in, but they introduce some funky angles and make the brakes come in heel first, and interfere with the tire sidewall, so that's not going to work out.

Unfortunately, the answer is going to be to send the frame back to the builder to have him redo the canti studs and re-powder coat the entire thing.

  • Is it too late to consider changing to disk brakes? If the frame needs additional welding, even adding just the caliper mounts might allow you more options in the future.
    – Criggie
    Feb 15, 2018 at 0:02
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    The bike was refitted with longer studs and now it is built up and working well.
    – user36575
    Apr 3, 2018 at 0:34

This is a collection of thoughts rather than a real answer, but pictures don't work in comments.

Some v-brake pads have permanent shoes in which are fixed replaceable pads. I'm sure I've used some in which the stud was a normal M6 bolt, which you could swap out by removing the rubber pad. However the ones I currently run (Kool Stop) use a custom-headed bolt:

brakes with removable shoes

Maybe this will jog someone's memory, or maybe you can look around for ones that use a similar construction but the usual spherical washer arrangement for alignment.

Alternatively if you're prepared to use the spacers you bought already, you might be able to make them work on these pads, as you don't need nearly so much male thread for the alignment. You may need extra nuts/spacers, and a lot of care and threadlocker -- I'd be cautious about extending the thread giving that you're relying on a single point fixing to stop you.

Canti pads have a much longer post. Unfortunately at ⌀7 mm I reckon it's too thick to cut an M6 thread unless you can find them with alloy posts (I've got a few different ones but they're all steel; online I find rumours of alloy posts).

Canti vs. V pads

Not all v-brake pads have the same length of stud. Unfortunately I think you've already got fairly long ones. I have some cheap but effective XLC pads with 25 mm unlike the ~22 mm of my other pads.

Finally, there exist v-brakes which take canti pads. I have some on an MTBSO I use as a shopping bike but plan to keep outside work: MTBSO V-brakes

These are cheap and nasty, and came on a bike I date to early 2000s (which seems like the forks were badly built, if you're wondering why the brakes look wonky). They might help, but on the other hand they might not, as the canti adjustment method needs a little more length than the typical V-brake method.

  • Thanks, those are good things to know if my spacer/extender idea (the easiest step 2, since I had the material sitting around) doesn't work out.
    – user36575
    Feb 14, 2018 at 1:16

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