To fix that, I've just ordered a very loud portable bluetooth amplifier, which can drive a speaker or two, of virtually any (normal home hifi) size:
Transform any speaker into a great sounding, portable Bluetooth speaker. The #saveaspeaker campaign continues into 2015
thevamp.co.uk
There's also this PA app for my phone:
Connect your phone with bluetooth speaker, works as remote speaker or megaphone.
play.google.com
...which should work if I connect a headset with a boom arm mic. I can then speculate about the weather at random strangers I cycle past, as well as shout very loudly at cars. I can't wait for the amp to be delivered - it's a Class-D, about "30W", which is enough to drive anything up to one of my unused floorstanding speakers. Actually three of these at 50W each would probably be better (waterproof):
Find many great new & used options and get the best deals for 4 inch waterproof boat outdoor speaker, suitable for ATV UTV RZR golf cart jeep at the best online prices at eBay! Free delivery for many products!
www.ebay.co.uk
Or a few of these:
Weatherproof PA speaker for use with any CB with a PA facility. These are for use on a CB, PA system etc. They can be used in place of any standard 8 ohm speaker. They arenot suitable for use on phones, MP3 etc which have a headphone socket rather than a speaker socket.
www.ebay.co.uk
If not loud enough, adding a couple of these too is an option:
Find many great new & used options and get the best deals for TPA3118 PBTL Mono Digital Bluetooth Amplifier Board 1*60W/2X30W 8-26V AMP Module at the best online prices at eBay! Free delivery for many products!
www.ebay.co.uk
Cars will hear my roar!
...or a loud looped recording of a Ferrari engine, Triumph motorbike, or just my heavy breathing.
Hey it might cheer people up.