Two alternatives to Schlumpf Speed Drive?

With an MSRP of $300 is looks VERY attractive to me than 600-700 for the schlumpf one. They say all you need is a standard 68mm bottom bracket shell. would the strida 5 need some modifications for this? cause I never took apart my crank to my bottom bracket so i’m not sure if that’s what we have there. As for the gear changing, if they are going to sell that for $300 I’ll find a way to run the cable one way or another or position it just around the crank area so you can kick it to switch high and low.