I'd prefer two lights about half that size, one each side. Keeps your view clear around your front wheel and offers some redundancy since it's unlikely they'll both drop out at the same time.
On the other hand for MTB a helmet-mounted light is a better option a lot of the time.
I got an Exposure Diablo mk10 for £130 from Wiggle's eBay account (ex-display, returns etc). I've only needed 1500 lumens for short sections, so a battery that manages 1hr at full hasn't been restrictive.
I'd prefer two lights about half that size, one each side. Keeps your view clear around your front wheel and offers some redundancy since it's unlikely they'll both drop out at the same time.
On the other hand for MTB a helmet-mounted light is a better option a lot of the time.
I got an Exposure Diablo mk10 for £130 from Wiggle's eBay account (ex-display, returns etc). I've only needed 1500 lumens for short sections, so a battery that manages 1hr at full hasn't been restrictive.