I don't know how many bikes I've built with non-aero brake cable routing, but many. I'm never really happy with the result. The loops might be a touch off left v right or be a bit big or small. It seems that if a loop is too big and I trim it, then it's too small.

So, what tips do the experts have for getting housing loops "right?"

I start with a bit too much housing and, if it does not offend my sense of proportion, I leave it as is. If it does look too wonky for me, it's usually rather easy to see how much it should be shortened.

you will get it perfect for you and then some other bozo will chime in and mess with your mind

get it close, say "damn that looks good" and ride the heck out of it

Yeah, I take waaaay too much time snipping a few mm's off the housing end(s) to get them the same loop height.

When making so many small cuts, I clean the end with my Park cutters inside a plastic bag so the spiky shard doesn't fly away only to be found by bike tire or bare foot.

I usually make the rear brake housing a tad too long, and then I can pull a little excess out the back so that the "whiskers" are the same height in the front.

Mine tend to resemble the St. Louis Arch. I alway s get "feedback" when I post a photo of one of my bikes. I'm OK with it; traditionally, I've worried about the bend being abrupt enough to add friction in the system -- then again, I pre-date lined housing.

Cut once and let it go…! Adjust the rear cable a bit.

Get the rear housing 'perfect' first. It's easier to trim the front brake's housing, it's a simpler and shorter run. And if you do cut it short you're wasting less housing. Other than that... don't take short cuts, really place the housing with ferrules into the brake lever and caliper, and close the caliper slightly to mimic its default position closer to the rim. Feeding the cable through and using a third hand tool will hold the housing and caliper in place for you, allowing you to check the symmetry from all angles.

Perhaps also invest in those plastic cable housing clips. They hold the two lengths of housing together where they cross, helps to regulate the bends.

I don't worry about it, so long as it does not interfere with riding it.

If it did bother me, the easy fix is to buy pre-assembled and restored bikes from other BF members, where they already freted over it. The only problem with this method is that I prefer my right hand for the front brake. It seems most people prefer the opposite.

Cut it until it's too short.
Buy more.
Da Capo.

I measure twice, cut once, show the pic on BF and get criticized, then recut.

I like or resemble all of these! Thanks.

Thanks for the feedback folks. The way you describe the process, y'all sound about as competent as me. I thought for sure someone would have constructed a jig for this which peaked at just the right height and mimicked the curve of a chambered nautilus shell.

I paint the longer loop a darker color so it seems smaller.

Foolproof is an oxymoron. You're on your own.

Was hoping to get some formula, such as top tube plus stem length plus xx" = rear cable length. Current process is time consuming, but test-run housing from rear caliper to lever, cut, install, then measure front with same arc/height as rear.

"...aaaannnd that's close enough for government work..."

I got a job at a Gov't. mfg. facility (yes, they actually still have a few) several years ago, shortly after I started I jokingly made that statement. My co-workers were, shall we say, not amused.

I like em’ tight. No floppyness on my bikes.

I always assumed the phrase was a reference to shady suppliers selling substandard materials to the government, not actual government employees.

I measure they match, and I prefer them as short as they can be while also offering smooth steering and no braking from steering. I also cut an inch too long at first to ensure that when I get on the bars before I tape them, the bar angle and the position of the levers is where I want it. Once I have all that, I'll clip the housing to the right length, tape my bars, then fully get my brakes done.
Phil

yes with the additions-

I avoid where the cable housing effects unaided steering.
there is a whole cadre of people that have definitive rules for crossing cables at the handlebars. I do not care what other people think.
Some bikes, a Raleigh International in particular, the top tube cable stops and guides make cable routing difficult.
i use right lever to rear, many owners guide the cable under the bars, not my favorite look but I understand why.

Part of my process is to not have my hands catch a loop as I take my hand(s) off the bars. I bought a Colnago once with the loops Merckx "short" , as material came up I lengthen the loop a bit to not have my hand catch it.

My brain instantly went to the loop around the seat post and center pull brakes and thought 'mmmm, you don't'.

I'd say it applies to both. My experience working for the government was that if you were a total screw up they promoted you to a position where you could do less damage. I saw people in positions they were completely unqualified for and not just a few. They needed a tooling engineer but one of the requirements was a 4 year degree regardless of how much experience you had. They turned down one guy I knew who had 20 years experience and was REALLY good at tool design and fabrication. They hired some kid straight out of college instead because he had that 4 year degree............... in forestry. I kid you not.

Gad. Whoever designed that was not thinking. I'd suggest using a length of the old Suntour Barcon housing -- the uncovered coil -- because it is flexible enough to handle that kind of curve.