What *are* bottle dynamos like now? Havent used one in about 30 years..
Got an Axa on barakta's trike (for which the only hub dynamo option is an even more expensive than usual Schmidt), which cost all of about 20 quid. It's driving a (non-R) Cyo and a pair of Spanninga Pixeos.
Current impressions, based on a relatively small amount of mileage, but quite a lot of which required lights:
- The system works, in exactly the way I expect a dynamo lighting system to. The main functional difference between it and a SON Delux + Cyo is that the output is disappointing at low speeds. You need to be doing 10mph or so to get decent light-to-see-by (though there's plenty for being seen while crawling up hills at walking pace). We've been doing a lot of Sustrans path type riding while barakta builds up some cycling fitness, and performance in the slow fiddly bits is significantly less good than my DH-3N80/Cyo-R setup on the Dawes. However, I found it fine while riding the trike myself at normal road speeds.
- It's not silent, but the noise isn't all that noticeable at normal cruising speeds while riding the trike (where it's tucked in behind the seat - I'd expect it would be annoying on the front wheel of an upright bike). It's more apparent to the rider behind.
- We haven't experienced any problems with it slipping. It's been wet (plenty of puddles, pissy rain and a couple of runs through a ford), and mildly muddy (towpath type stuff), but not through snow slush or anything. I chose the Axa specifically because it had a good reputation for noise and traction. (This is with a Marathon Plus tyre, which incorporates a dynamo track)
- The electrical contact on the dynamo connectors went intermittent at one point, so I re-did them. Not had any problem since. May have been my fault. If it turns out to be dodgy again, I'll replace the no-tools vampiric plastic arrangement with spade connectors or solder or something.
- The dynamo incorporates a voltage limiter, at 8V. This is suboptimal for powering loads that can make use of higher voltages (LED front lights like the Cyo, the better USB chargers). I suspect it also means the dynamo is wasting significant power when not electrically loaded. Obviously this is less important in a bottle dynamo, as it can be mechanically disengaged.
- The case is glued shut, preventing me from non-destructively knobbling the above limiter circuit
All things being equal, it's really not bad for 20 quid. I'd especially recommend them as an interim measure where the up-front cost of a dynamo wheel in addition to lights is unreasonably expensive (make sure you buy the hub dynamo versions of lights, which includes a switch, though). We'd already broken the bank with the trike, and the SON was an easy thing to leave out - it's a wheelbuild and simple wiring job to retrofit if barakta ends up being a serious tourist / night rider. As is, the bottle dynamo is fine for irregular use.
