fahmidik

Hello, ladies and gents. I have been restoring an old Dürkopp 7 speed bike lately that needs new brake cables and a cantilever bowden. However in amazon I see different sizes for the length. How can I decide which one is appropriate for me? The sizes available are 73, 82, 93 and 106 mm. I can't post the link due to the 10 post rule but its named as "Brake Cable Y - Connection Cable for Cantilever Brakes - 01110120-23" on Amazon.

Apologies in advance for my noob questions!

yadder

buy and cut what you need size dude. Thats simple

Eggman84

That does not work for most cantilever brake link wires, which need fittings at both ends. Yes, old style link wires that went over a straddle had a fitting at only one end, the other end secured under a pinch bolt on one brake arm.

For the OP, suggest you read Sheldon Brown's treatise titled .The Geometry of Cantilever Brakes, which you can find at https://www.sheldonbrown.com/cantilever-geometry.html

ClydeClydeson

Any modern cantilever brake* can be used with a separate straddle cable and cable yoke. Shimano started the push to fixed length straddle cables in the early 90s, which was a major step backwards IMO. Except for having only one nut to tighten instead of two, there is no advantage to the fixed length straddle cables. Straddle cables and yokes are available and are superior for the adjustability compared to the fixed length ones.

THe only exceptions I can think of are MAFAC cantilever and old 'high profile' cantilevers brakes, which do require a fixed length straddle cable with a head on both ends.

Eggman84

There was a very real reason why Shimano (and others) went to the "link wire" style. And that reason was SAFETY. With the "old" style one piece straddle wire, if the main brake cable broke, the straddle wire would drop onto your knobby tire, locking it up. Probably not to bad if iyt was your rear tire, but maybe not so pleasant when it was your front tire that locked up, sending you over the bars. Two solutions, one was to use the link wire, the other was to put a bracket (usually with a reflector attached) between the straddle cable and tire.

Karl

ClydeClydeson

Good point - it is smart to put some sort of bracket or a fender/mudguard to stop a straddle cable from landing on the tire, but this is very different from the brakes 'requiring' fittings at both ends - most (all?) modern brakes do NOT require two fittings built in to the cable - there is a pinch bolt on one brake arm and an anchor for a cable end on the other. Any fixed length straddle cable 'triangle' as OP linked can be replaced with a separate straddle cable and yoke.

rekmeyata

Why not just measure the old bowden wire length and order the same length for a new one? I would think the original cable would be the correct length since they manufactured that brake.

thook

ime, the quick links work well with low profile canti's with post mounted pads (pictured below). the posts allow you take up adjustment for MA where the fixed link leaves off. even still, getting the correct length for the link is pretty critical. i found the preferred length for my use, but i don't remember it offhand. at any rate, i've use these low profile brakes/links on several bikes (mtb and road) over the years and, with salmon pads, had great success. i also like how easy the links were/are to use when removing the wheel.
i have a friend that has some avid 6 with a link and, when i set them up for him, i never could get those brakes to stop nicely. may have been the pads, but i've since come to think the link just doesn't work well with their design. and, i think they're considered a mid profile. but, they also have the thread pads with spacers...which i really don't care too much for, personally

low profile shimano...


btw, if the old low profile canti's left something to be desired from bitd for anyone, i dare say the pads used then didn't do the brakes justice. salmon pads make a big difference

thook

well, that'd just be too simple
besides, don't they come in a universal length and you just trim off what you don't need?

dsbrantjr

Those link wires are very difficult to adjust correctly so I always dump them for a straddle wire/cable hanger setup. The bracket or even a loop of twine is simple enough to install if it does not already exist; if the bike has fenders they are sufficient.

blamester

The different lengths are to adjust the brake to your preferences
Unless they are very expensive buy all four and pick the best length for you.

cyccommute 

In theory, yes. In practice, how often does the cable just break? I’ve had at least one cantilevered brake equipped bike since 1983. I’ve often had multiple cantilever equipped bikes. Today, I have 3 of them. I’ve also owned a total of 38 bikes over the years...plus about that many for the rest of my family...with various kinds of brakes and used in a variety of conditions. I’ve never had a cable just “break”. Even if a cable slips, it’s seldom fast enough to cause the kind of problem that you are bringing up.

I also add that I have worked on 15,000 bikes at my local co-op over the last 10 years. No bike I’ve worked on has ever had a broken brake cable. There have been some loose ones and not a few frayed ones but not one was broken. Where are all these broken cables that Shimano had to develop this safety feature for? It’s a solution is search of a problem.

thook

seems to me the biggest "potential" problem would be the yoke coming loose. the straddle cable would just flatten out over the tire top when the calipers spring outward. yeah...i could see that being an issue...maybe...if you don't get that yoke nice and tight. and, yeah..if the vertical cable broke, but i've never had that happen, either

JohnDThompson 

Another reason to use mudguards!

Sluggo

If your brakes require a cable with two fixed ends (as do my old Dia Compes), you can use a long single-end cable (or a flat-bar brake cable) and a Knarp. Trim the cable as needed.

Odyssey Knarps, Slip-free Cable Anchors, sold as a pair - Modern Bike

oldbobcat

The straddle cable length is correct when it forms an approximate 90-degree angle at the harness at rest.

oldbobcat

You got that right.

I guess all those fools out there running side-pulls, linear-pulls, mechanical discs, and hydraulic discs are courting certain death by theoretical brake failure.