I volunteer at a charity bike store. We collect donated bikes, all types and vintages, repair them and sell them. The procedes go to a charity program. Last year we sold 2k+ bikes. As you might quess, not all of the bikes can be fixed for sale. So these bike are stripped for usable parts. And since the people that are doing the stripping of the part are volunteers as well, they have different skill levels. Some don't know that there is a difference between v-brake levers and canti levers, they all go into the brake lever bin. So when I need a lever from the bin, I won't know which bike it came off of, or what kind of brakes the bike had.
My question is; How cna you reliably tell a no-name, unlabeled v-brake lever from an unlabeled canti brake lever?
We want these bike to be as safe as possible when we sell them.

High School Physics, applied.

https://en.wikipedia.org/wiki/Lever

ClassicalMechanics.. It is about Leverage, Mechanical Advantage..
Fulcrum/pivot relationship to where the effort is applied and the work being done.

a V brake caliper has high MA, significantly more cable pull to pad moving towards the rim (a ratio)

in order to supply enough cable pull the hand lever must have a low MA
and pull more length of cable.

cantilevers brake levers need to pull less cable, the hand lever has the higher MA
the caliper a lower MA.

also Note: there are 2 types of levers used in cantilever brake calipers.

only type one 1, where pivot is between cable pulling and brake pad,
is the high profile L shaped type..

compact/low profile and V brakes the pivot is the . so is a type 2 laver.


in short, you should be able to judge the MA of the lever in your hand,
by applying some ancient science, as you squeeze the lever.

The easiest way to identify and sort levers according to cable pull ratio is to measure the distance from the lever pivot to the cable head swivel. The greater this distance the less leverage, and the greater cable pull. Longer pull is for V-type, short pull for canti's and sidepulls.

This thread has proven to be very useful.

Now, can you use a v-brake lever with cantis or calipers? I know its not suggested, but is it manageable?

Brake leverage or pull ratio isn't digital, ie. canti vs V-brake. There's a spectrum with clusters near either end. Note also that while calipers and V-brakes have set leverage, canti leverage changes with the length of the yoke cable.

So you have some latitude, and for example a low pull lever might work with a V-brake if it's adjusted close, but it won't pull enough if wheels that aren't perfectly aligned force you to set the brake more open.

I'd start by sorting the levers, then try what predicts to be the best match, and push the limits if or when it's necessary and workable.

A canti/caliper lever will be about 28 mm from pivot to brake caple attachment. A v-brake lever will be something like 35 mm or more.
There is the occasional intermediate oddball out there, which ends up inbetween, but I've only come across one.

Note: the numbers are off the top of my head. I've posted about it here earlier, fresh after a measuring session. If you want any better, track that post down.

Depends on how finicky the rider is, general brake setup performance, and rider hand strength.

For someone with full use of their hands and decent hand strength, the mismatch isn't any worse(rather better) than braking on steel rims, or braking in the wet, which people tend to do "all the time" w/o any disasters happening.
It's like with most things, you can afford one feature being substandard and still do OK. But if you get several things stacked up against you simultaneously, you're in trouble.

THere are little pulley devides sold (often called 'travel agents') that are designed to replace the cable guide (noodle) on V brakes and are designed to increase the amount of cable pulled and cut back on the tension. I have mounted a set of these in reverse - next to the brake lever and witht he cable going through the opposite of intended way - between some poorly performing levers and a set of crappy BMX caliper brakes on my 6 year old son's bike. My intent was to increase the cable tension for the limited stregth of his little hands, and I was somewhat successful. I suspect you could do the same thing to mate a V-brake lever to a set of cantilever or caliper brakes.

It is not recommended that you mix and match. Sure it can be done and should be "ok" but when you need the brakes in a hurry, they won't all be there. I had the wrong levers on my bike (v-brake lever on a caliper brake) and when I was going down a steep hill, i wondered why I had to squeeze my brake extremely hard to get it to slow down.

Good to know, thanks guys. Also: measurements provided will eliminate the need to mismatch!

They're designed to allow the use of canti/caliper levers together with v-brakes. Running them in reverse would require some creativity in where to put them, but it would sort the pull out.
For a charity bike store I suspect that their cost would automatically make their use impossible.