brake lever - cross-type, Q...

[beardy]

Because we are used to considering real life near-rigid as being rigid. Like a rigid bike frame for example.

Your expression is true in a pure theoretical way but the system would still work with two rigid steel pipes as outers on rigid stops with just a tiny bit of flex in the right direction.

If there was a 200mm distance from the brakes to the cross top lever you could get the 5-10mm separation just by moving the outer sideways, it wouldnt have to bend at all, just as the outer between STI and crosstop lever doesnt appear to bend at all in use.

[pwa]

On my wife's bike, with Tektro Oryx cantis, the interrupter levers (is that the right name?) provide very solid braking. But they do take up a lot of bar space and make light fitting a pain.

[andrewjoseph]

My wife found they didn't work well on her spesh dolce, no matter what i did, the movement of cable outer was not enough to give good braking, front or rear. she was much happier with them off.

i didn't like them when i tried her bike, too mushy. ok for slowing, no good for stopping.

That's a clear indicator that they were not set up properly - in my 10 year experience I've found them to be as good, sometimes better than the main levers.

Lets get this right because its important, the cable outer should not be moving as such, rather it is being compressed - if spiral outer is used it doesn't work properly, you have to use linear brake outer.

the outers were as stock from the shop. i tried all sorts to get it working properly.

[531colin]

Because we are used to considering real life near-rigid as being rigid. Like a rigid bike frame for example.

Your expression is true in a pure theoretical way but the system would still work with two rigid steel pipes as outers on rigid stops with just a tiny bit of flex in the right direction.

If there was a 200mm distance from the brakes to the cross top lever you could get the 5-10mm separation just by moving the outer sideways, it wouldnt have to bend at all, just as the outer between STI and crosstop lever doesnt appear to bend at all in use.

In real life, the outer has to be flexible enough so you can steer the bike.

[beardy]

No problem with the front brake as the handlebars and brake levers stay in the same relative position.

[simonineaston]

Now don't you good folk worry about what may or may not be misinterpreted...
As I said, I am happy to know that they'll work - how well they work, I'll let you all know in due course.

[foxyrider]

.......... the cable outer should not be moving as such, rather it is being compressed - if spiral outer is used it doesn't work properly, you have to use linear brake outer.

Would that be the linear brake outer also sold as non-compressible outer?

non-compressible outer - well i've never heard it called that but yes it is.

Of course the outer is moving....cross top levers work by moving the outer, other levers work by moving the inner, mostly.

No it isn't 'moving' the outer, it is compressing it lengthwise. Yes it will move but only in as much as the lever is moving the inner and outer, it isn't that which is making it work. I know it can take some getting your head around it - you need to look at a bike which is set up properly with them to understand what is happening.

Nuff said, it works and i'm sure the OP will either love 'em or hate 'em!

[531colin]

No problem with the front brake as the handlebars and brake levers stay in the same relative position.

But in this case, neither end of the front outer is held in a fixed position. The handlebar end is moved by the cross-top lever, the brake end moves the brake. It probably would work with a rigid outer.

[iandriver]

Doesn't any barrel adjuster work by making the outer shorter or longer? I've never clamped any inner cable to any adjuster.

[andrewjoseph]

No it isn't 'moving' the outer, it is compressing it lengthwise. Yes it will move but only in as much as the lever is moving the inner and outer, it isn't that which is making it work. I know it can take some getting your head around it - you need to look at a bike which is set up properly with them to understand what is happening.

Nuff said, it works and i'm sure the OP will either love 'em or hate 'em!

if it was compressing the outer without moving it, that would make the inner cable slacker in the system. the opposite of what happens. therefore, it is the movement of the cable outer that forces the inner to move and actuate the braking. you can actually see the cable outer changing shape to a tighter radius.

[simonineaston]

Content tho' I am to wait 'till I see my cross levers in action, I have continued to think about this concept which, if I may say so, obviously causes some of us a modest amount of conceptual angst... not least myself, and what I say is this.
Combine Isaac Newton's 3rd Law of Motion with an extract from Sheldon Brown's ever helpful compendium of all that is cycling, and we're nearly there!
"To save weight, many bicycles substitute the bicycle frame for some sections of the housing. This is done by attaching "cable stops" to the frame or fork. A cable stop has a socket to receive an end of a cable housing, and a small hole or slot through which the inner cable can pass, but the housing can't. The "push" of the housing is transferred to the frame, so the inner wire can run bare until it gets to another cable stop facing the other way, where the "push" from the frame is transferred back to another length of housing."
I hadn't really thought of like that, but now I do, it helps!

[beardy]

I wouldnt go for either of those two descriptions of what happens. (prior to Simon's post)

The interrupter levers make the outer cable effectively longer (rather than compressing or moving) by opening up a gap in the outer cable when you squeeze the lever.

The new effective length is real length plus gap length. The real length will be a tiny bit smaller due to compression but that acts against the braking action not helping it.

[stewartpratt]

No it isn't 'moving' the outer, it is compressing it lengthwise. Yes it will move but only in as much as the lever is moving the inner and outer, it isn't that which is making it work. I know it can take some getting your head around it - you need to look at a bike which is set up properly with them to understand what is happening.

That's the complete opposite of what's happening. The lever is pushing two sections of outer apart.

Here's something to imagine. (Or try, if you're super keen.) Dismantle your rear brake cable. Take the front length of outer (or the whole lot, if you have full outers). Cut a new section of outer that's 1cm longer. Replace the former with the latter and reassemble.

You've just replicated pulling on a cross lever.

If the outers were compressing, then for moving that lever you'd not see any extension in that cable, so it'd be like reassembling it with your original section of outer: no change.

If you want to test what happens when your outers are compressible, cut an inch of outer out of the middle of one of your sections and replace it with an inch of rubber cable donuts…

[andrewjoseph]

just found this:

http://velonews.competitor.com/2015/05/video/ask-a-mechanic-installing-secondary-cross-brake-levers_371974

you can see the movement once installed, about 2:12 in the video

[531colin]

No it isn't 'moving' the outer,................ Yes it will move but only in as much as the lever is moving the ....... outer, ...... ............you need to look at a bike which is set up properly with them to understand what is happening. ......

No, it really isn't me thats confused.....