Inline brake levers

Hey guys, being a noob at bike building and living very far away from my lbs, is it possible to use inline brake levers for your primary brake levers?
This is the last thing I have left to do on my build, and it's such a pain in the arse.

Yes and many people do. I did for about 2 years. Some people prefer to use gear cables as they have smaller heads on them making a neater finish when they slide into the cups. Not sure it matters though.

Gear cables are thinner than brake cables and the wires a braided differently. The outers are also different. No doubt there's a good reason why the difference but I don't know what it is.

Gear cables are thinner than brake cables and the wires a braided differently. The outers are also different. No doubt there's a good reason why the difference but I don't know what it is.

Difference in outer cable is braided (gear) v coiled (brake) - generally, braided brake outer is available, normally reserved for bmx type use though where it has it's own advantages. As far as I know the different types of outer are used because coiled has a bit more give and so provides better brake modulation/less lock ups and braided is nice and stiff so snappy/crisp/precise gear shifts.

Inners are a different size, gear cable being smaller. It has less force/load to carry and if a gear cable breaks, so what. If a brake cable brakes, might cause acrash.

When you apply tension to the inner of a Bowden cable, you apply equal compression to the outer. Brake outers are formed from a single coil of square edged wire. They withstand compression by squashing the coils together. There can be a bit of give before the coils touch, especially on newly installed cables that aren't yet used to the path they're following.

Gear outers have many wires in a shallow (almost longitudinal) helix. These strands take the compression along their length and are only restrained from buckling sideways and bursting out of the cable by the plastic outer coating.

(In contrast, you could strip the coating off a brake outer and it would rust but still work.)

When you bend a brake outer you open up gaps between the coils on the outside of the curve, but on the inside of the curve the coils can't get closer together once they're touching. This makes the path along the middle slightly longer, effectively shortening the inner. These small changes in length with different cable bend are tolerable for brakes but bad for indexing.

When a gear cable is bent, (thanks to the helix) each strand of the outer will lie partly on the inside of the curve and partly on the outside, and there is enough give in the system to allow the slack on the inside to cancel out the lengthening around the outside of the curve, so the path along the middle of the cable remains about the same.

Gear cable style brake outers do exist, but they have an extra wrapped or woven layer over the longitudinal strands to stop them bursting out. I think they can be better all round, but are more complicated to make.

Apart from ends and thickness, i don't think there's any difference between brake and gear inners - the ones i've just looked at both have the same 1,6,12 concentric winding pattern.

best of both worlds is to carefully file the ferrule on a brake cable so it slips in to the hole neatly. If you can be bothered.