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Can you build a custom brake straddle cable?

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Can you build a custom brake straddle cable?

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Old 11-30-17, 01:39 PM
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curbowman
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Can you build a custom brake straddle cable?

I have read two respected people claiming the straddle cable on a centerpull brake should be as flexible and short as possible. Thing is, most brakes have one straddle cable and there's no way to adjust it!

Or is it? Has someone tried to build a custom length straddle cable for their centerpulls?

Here's what Jan Heine from Compass Cycles has to say about it:

"The straddle cable carries only roughly half the load of the brake cable, so it needs to be only half as strong. A thinner cable is less springy and conforms much better to the bend of the cable hanger. [...]our Compass brakes use a thin shifter cable as the straddle cable. When you squeeze the brake lever, there is no lost motion."

https://janheine.wordpress.com/2016/...es-done-right/

And Nola Wilken, who has restored more vintage bikes than I could even dream of, shares Mr. Heine's experience:

"The length and width of the straddle cable is another important element to consider when setting up these brakes. [...] More flexible and moveable cables (a la Mafac and Compass) will provide better performance. One of the nice features of Mafac brakes is that the straddle cable is actually a shifter cable cut short, so it is easy to replace and adjust these straddle cables for Mafac brakes, at will."

" In my experience, the length of the straddle cable is not so important as its angle – a wider angle at the yoke being more advantageous. The angle will decrease as the brake lever is applied."

https://restoringvintagebicycles.com...erpull-brakes/

So, my question is: is there a safe way to build a custom straddle cable at home?



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Old 11-30-17, 01:53 PM
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nfmisso
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"So, my question is: is there a safe way to build a custom straddle cable at home?"

It depends on the tools and skills you have. A couple hundred dollar casting kit from Amazon, some zinc alloy (lots of internet sources), basic tools and you can cast ends on cables.
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Old 11-30-17, 02:17 PM
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You could solder brass ends to cable. We used to do that BITD. The holes in the brass barrels have a funnel shape so you can unwrap the cable to make a positive stop before soldering.
Not very scientific, but you can test it by squeezing the lever as hard as you can...
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Old 11-30-17, 03:33 PM
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use old school VW bug throttle cable ends...

as to straddle cables... they are easily adjusted, can be just about any length needed if you can "make them", and easy to bend to fit once correctly centered... oh dang, i just gave away a COMMON brake tuning technique i've known since the 60's... oh well.... i was ten when i realized bending the bridge cable reduced mushy brake feel.... Center Pull 101.... Weinmanns on Lygie Duralumin: alter setup to fit new sew-up("tubular") rim width.

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Old 11-30-17, 03:47 PM
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Heine is a high end guy selling to well off people.. the center pull transverse cable has 2 cast zinc barrel ends

its a copy of dia compe, weinnman brakes from the 70's, they dont need adjustment, the pull is straight up

bike shops del Norte can ship internationally, spare parts..

[Mafac has one barrel end and the other end a pinch bolt, to use a cut off gear cable.... that is what they copied; left end of your 'compass' picture]


full DIY? the end of the cable is frayed to grip within the zinc cast around it..

can you make a foundry in your shop, to melt and pour zinc?

Other workarounds involve set screws in a piece with a hole in, & across it.. to grip the cable, made by threading and drilling..






....

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Old 11-30-17, 06:35 PM
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The length (and resulting angle) of the straddle cable affects the leverage of the brake system. To make a statement about straddle cable length without acknowledging this is lacking in complete understanding. As to a thinner cable having less springiness as it gets pulled by the cable carrier I say- get rid of that stupid pulley carrier and use a traditional folded metal one. Why? because the common folded metal carrier tends to grip the straddle cable better and allows for one more pad centering method, additionally the radius of the pulley is smaller then that of the carrier so the carrier is "easier" on the cable. Andy.
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Old 11-30-17, 07:12 PM
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that point about the straddle carrying only 'half the load'
is wrong. the tension it's under varies significantly depending on the wire angle. and it many cases is Much Higher than the vertical brake cable.

So, I'd be wary of that article.

as for making a more flexible cable
I'd suggest using braided cable, rather than reducing the diameter....
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Old 12-01-17, 12:39 PM
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Good point about the Mafac centre-pull cables - countless competition pros used these for many years on the famous Racer series brakes. As soon as I saw them it seemed a blindingly obvious way to provide adjustment.

Originally Posted by fietsbob View Post
Heine is a high end guy selling to well off people.. the center pull transverse cable has 2 cast zinc barrel ends


[Mafac has one barrel end and the other end a pinch bolt, to use a cut off gear cable.... that is what they copied; left end of your 'compass' picture]


full DIY? the end of the cable is frayed to grip within the zinc cast around it..

can you make a foundry in your shop, to melt and pour zinc?

Other workarounds involve set screws in a piece with a hole in, & across it.. to grip the cable, made by threading and drilling..






....
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Old 12-03-17, 08:45 AM
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Everything you would need you can buy, 20yrs ago I bought a Cable Building kit ( $500 ) for building custom cables in the power equipment industry, the company sells kits for Motorcycles, Bicycles and a whole host of other kits. They are still in business and the last time I needed fittings they sent them to me & billed me, about $1.00 and up per fitting. Lots of equipment uses the same fittings as bicycles.

Glenn

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Old 12-03-17, 10:20 AM
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If you search the interweb for guidance, use the search term "Bowden cable". That's the technical name for cables with the little cast-on ends. There's a guy on ebay that goes over how to create custom throttle/brake/clutch cables here:
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Old 12-03-17, 10:44 AM
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Originally Posted by WizardOfBoz View Post
If you search the interweb for guidance, use the search term "Bowden cable". That's the technical name for cables with the little cast-on ends.
Really? I didn't take time to look it up but I've always thought that was the term for a cable in tension surrounded by a flexible housing in compression.
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Old 12-03-17, 10:57 AM
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Originally Posted by Retro Grouch View Post
Really? I didn't take time to look it up but I've always thought that was the term for a cable in tension surrounded by a flexible housing in compression.
I think you're right, but in practice the term generally includes the cast-on or soldered-on heads. So if you search for Bowden cable ends you find the reference I cited.

An earlier post discusses soldering brass fittings on the cable "back in the day". If I were the OP, I'd fashion the brass fittings in the shape I wanted, would drill those fittings for the cable (chamfering the outboard ends of each) and would then solder the fittings on as shown in the URL cited above.
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Old 12-03-17, 12:24 PM
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As an addenda, Carroll Smith (the auto racing expert) spoke disparagingly about Bowden cables in racing vehicles. By which he meant the typical 9 strand cable with cast-on end. But then he goes on to describe "aircraft quality" flexible cables, with crimped on low-friction bearing ends. I think this is where I got to thinking Bowden cables were only those with the cast-on ends. Examples of both below

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Old 12-06-17, 11:26 PM
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When you are talking about MAFAC brakes, and also cantilever brakes, don't forget that the position of the brake pad in the holder affects the angle of the straddle cable and hence the mechanical advantage.

I discovered this at our last work day at the Bike Exchange. I was cleaning up an old mountain bike with canti brakes and they felt squishy. I put a shorter and then a shorter still straddle cable on the brakes and the levers still felt sloppy. The brake pads were inserted all the way in the holder and were forced to hit the rim at an angle. I loosened everything up and re set the pads higher in the slot and pulled them half way out so that 3 of the notched rings were visible between the holder and the pad. This allowed me to level the pads so that they contacted the rim squarely . It also reduced the angle between the brakes and straddle cable. This gave much more positive braking and more leverage.

to summarize, don't forget the position of the brake pad in the holder affects the mechanical advantage and hence the power of the brakes.
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