Thanks for fixing the typos, @JamesBradbury. It also affected my vision, but hopefully not quite to the extent that I'll be crashing into parked cars!

If you check BMX brake items you can find a variety of levers with double cable pulls in a single handle. There are also "Y" brake cables that actuate two cables from a single lever. They are typically used with "Gyro" headsets.

Thanks @mikes, I'm seeing them on Google, I will look into them but, thus far, B/atman's suggestion looks ideal.

@PeteH No problem. It would be interesting to hear what solutions you find, so could you update the question or answer when you have something that works for you?

For mechanical (cable-operated) brakes you need something slightly more complex than a simple Y cable. Due to temperature changes, cable stretch, pad wear, etc, even if you precisely adjust the two cables from a Y to equally activate both brakes, there will be some imbalance in short order, so an "equalizer" (eg, a short lever at the head of the Y) must be used. However, this needs to have a "safety" feature so that all braking will not be lost if the cable on one side breaks or some such.

@mattnz - That's a good point re the front derailleur. I guess in the UK, discs might be nice for the rain, but rims should be adequate. I don't see a nice way to shift the front with one arm with a bar end or something and staying in control easily. Also, the part is a JTek Shiftmate in that case (which is a UK based company, so shouldn't be hard to find).

@DanielRHicks - That seems hard. With one lever, you're always going to have one brake cable out that can break, so you'd need something like a brifter and an interrupter lever. One of the brakes is hooked up to a splitter (e.g. Cable Doubler 2:1) with one end going to the interrupter lever, and the other to a combiner (e.g. Cable Doubler 1:2) along with the other brake, which is hooked up to the brifter. Then, if any one cable breaks, you still have braking. But you'd need to stick a bunch of barrel adjusters and stuff and faff with regular tuning (which is unavoidable).

And I'm not sure that that setup would introduce enough slop and stuff to not work well. The straightforward solution has 1 cable of failure, which is from the one brake lever to whatever setup you have. Something to think about though.

Actually, I guess one logical thing to do if you want an upright bike with two independent brakes is to have one rim brake to the lever, and an igh for the back with a coaster brake. You'd need to get a new brifter from Versa for the IGH since friction shifting the IGH with something like a Retroshift shifter + downtube shifter is probably not going to end well, and JTek's bar end shifter for IGH's is probably going to be a bit hard to use with one hand.

I would be very tempted to use back pedal brakes, but fitting the IGH shifter to drop bars will be an exciting challenge. You're into "custom bike build" territory just by asking that question. And Pete, welcome back, we miss you :)

As a side issue, I am looking at some of the offerings by the larger trike manufacturers. I can't believe that something weighing 28kg is being marketed as "lightweight"! This tank comes with 3x7 drivetrain. You guys with bikes don't know you're born!

Hey Pete! I'd like to suggest you're doing it in the wrong order. If your balance is suspect then a two-wheel bike might be unsuitable. As soon as you look at a tricycle or recumbent then there's a lot more variety, albeit cost tool. Have you considered a `bent?

You still have the same situation, unless you're using one of those levers which can operate both brakes at the same time (e.g. has 2 cable inlets). But the balance would be better.

@PeteH 28kg is heavy for a trike, but not unreasonably so if you're looking at a cheap or rugged one. Racing trikes should be under 20kg, unfaired you should be able to go under 15kg without too much hassle. My Rotovelo weighed 33kg with a Rohloff in it. Email me if you want pointers. KMX do 900 quid/19kg if you want basic and bombproof. Ice Sprint is lighter and nicer... but you pay for that

@Criggie, I am looking for a trike, I thought that was clear from the question? As regards a recumbent, anything low requires a tremendous effort to stand back up (even getting up from the couch was a major effort a few months ago!) So I really want something upright. But I've never heard of a "bent" - I'll check it out on the web.

@Móż I think 28kg is very unreasonable when a fast road bike weighs in the region of just 10kg. High 20s does seem quite typical of the larger manufacturers, who will obviously be looking to satisfy the needs of most punters, rather than my needs. However I have found a guy who says his trike weighs around 15kg, so I remain hopeful of finding something.

@PeteH upright trikes I'm afraid I know next to nothing about. I suspect needing three wheels, and needing much more lateral strength, makes everything very heavy. It's just a bad design IMO. There are some sitting-higher-up recumbent trikes, especially delta trikes. Greenspeed Anura is 18kg, Hase KettWiesel is 17kg. If you can deal with one of those I think it'd be better than an upright trike.

We're getting a little away from the question of brake levers - politely suggest this whole trike bit moves to chat.

Thanks @Criggie but I don't really need any advice about the type of bike to look for. Brake levers with added function, however, is a different matter!