Friday, April 12, 2013

Off-label use of brake noodles

Head-tube cable stops are one of the stupidest things ever put on a bike. Only a few misguided builders are still putting them on some road bikes, but many bikes are still in use from the period when they were the height of fashion. They replace the minor problem of cable rub with the massively worse problem of tortured cable housing leading to premature failure.
I've tried various tricks to extend the lifespan of the cable housings and improve shifting performance. This week I'm working on a Serotta I set up several years ago. Since then the rider bought fancy-zoot new carbon fiber bars as part of several upgrades. I didn't get to install them because of some scheduling issues, so she went to the triathlon shop where she has some sort of sponsorship. They have a great reputation. They specialize in fitting. But their mechanical work is strictly by the book, as far as I can tell.

Housings in head tube cable stops bend abruptly when the rider swings the handlebars further than a few degrees to either side. This can happen in low-speed tight turns or when stuffing the bike into small spaces, like the back of a hatchback or a small SUV. The book has nothing to say about this. Obedient mechanics just keep replacing housings and sending riders back out to develop shifting problems.

The new bars on the Serotta have internal cable routing like the old ones did, but the housing exits from the aero extension a little farther from the head tube now. The way the bars are shaped at the outer end, the housing HAS to run inside and go out through the hole provided.

The other shop had tried a sweeping curve, but still had a tight kink at the stop. I fiddled with different lengths and angles for an hour or so until I had a brainstorm.
Brake noodles direct a cable around a curve. If I could find the right radius and get the housing length right, the noodles would be able to change angle, rotating in the stops in a way that regular housing cannot.

The junction ferrules on brake noodles are drilled for brake cables, which are fatter than shift cables. To insure that the linear-wire shift housing wouldn't push through the junction ferrules I replaced them with junction ferrules designed for shift housing. It was a little tricky feeding the plastic liner of the noodle through the smaller drilling of the new ferrule, but it eventually fit.

To make the installation less conspicuous I put shrink tubing on the noodles.
Today I actually modified the system. The first noodles were both Jagwire, with a short bend. I replaced one of them with a slightly larger-radius noodle so they could swivel more easily past each other. It looks basically the same. The added clearance is only a couple of millimeters.

Noodles probably wouldn't help with older STI levers on drop bars, but now that everyone is routing their cables under the tape the housings exit closer to the headset. That means the cables come in more vertically, which would probably feed into the noodles successfully.

I will be conducting more experiments. I doubt that they will end up in the book.


Steve A said...

I imagine that the noodles would also help with the case of aero brake levers and center-pull brakes.

cafiend said...

Steve -- I'm having trouble visualizing the combination you describe. True center-pulls would use a headset cable stop which would center the cable above the bridge wire of the front brake. For a rear brake there are cable stops that hang from the seatpost binder bolt. Where would the noodle come into play?

Steve A said...

The noodle would get the cable around the turn where it comes out from the handlebar tape to the headset cable stop with less drag. Regular cable housing isn't real satisfactory in that regard as it moves when you pull the lever; with binding as a result.

cafiend said...

Ah. Some headset cable stops include a noodle-like piece small enough to fit the space. However, if you have one of the many that don't include that useful feature you could definitely adapt the linear-pull noodle to meet the need.

RANTWICK said...

Nice. Just nice. Brain use is so impressive to me these days...

RANTWICK said...

Now that's using your noodle!

Sorry. Had to.

cafiend said...

Someone had to.