To keep up with the SO's race bike riding and on her special request, I needed something to ride fast.
Now (edited Dec 2017), this has been superseded by a carbon road bike modification where I modified a Shimano Ultegra brake and shifter lever set for use [link]. If you are after the fastest, coolest, lightest, then better go there maybe.
Also, a different prosthetic approach is used there: a VC body powered prehensor.
Here, a fixed adapter with permament position for the whole bike ride has been available at the time I performed this choice of materials and modifications.
The case for flat handle bars
There are somewhat uncomfortable iliosacral joint issues that many bikers around my age have. There is the issue of having to move the shifters and levers to the left side on the handlebar. So the BMC Alpenchallenge with its conventional sitting position and a horizontal handle bar seemed like the obvious choice. Rather than a race or road bike setup.
The shop sales person the advised me to get the Shimano SORA version. So this made my choice a BMC Alpenchallenge AC01 SORA. Not the belt variation, which was definitely the right choice.
The BMC Alpenchallenge AC01 SORA comes with a 3550 50/34 chainwheels and a HG50 11-32 cassette. Thus, a 50/11 gear ratio for the Shimano SORA contrasts with a 50/19 as maximal gear ratio for the belt drive. So the conventional and not very expensive SORA transmission clearly wins the speed question.
Now, BMC introduced the Alpenchallenger line specifically for road bicycle riders that wanted the conventional "Herrenvelo" format. This is definitely a real bicycle (not some motorized gadget). It wanted to go just as fast as we rode our good old Swiss Allegro "Herrenvelos" back in the days: fast as hell. In other words, the Alpenchallenger was introduced as a commuter bike that can serve to chase e-bikes.
So to sum up in a nutshell, the bike is fast as hell.
It handles incredibly well. But it is too soft!
The way these are used is as follows: you use the fastest gear that the bicyle has, ever, you only use that gear. Then you stand up (from the saddle). Then you will pull the handlebar and crank the pedals with the fullest torque. The most power that has been given to you ever. This will invariably result in the rider/bike-combo's top speed, always. That is how I went (or, rode) to school back in the days. That is how to be as fast as one can ever be.
Attempting that with the BMC Alpenchallenger AC01 SORA is possible. It will require that one sets the springs in the Mert hand connector to a very high setting. So one can give the handle bar a full pull. And doing that then allows you to really maximize loading on these bikes. And, doing that then results in what?
Scraping sounds of the front disc brake : )
The total load on the bike obviously minimally deformed the fork and wheel. When cruising slightly uphill at maximal ache, maximal push and top pull - the wheel geometry (slightly) deforms. The issues are not new; look for lateral wheel stiffness when Google-ing.
If one builds bikes for urban racing that is the type of race technique they might have to withstand. Riders will be getting up from their saddle and going full blast at the highest gear ratio setting.
But it is cool that I ran into this, first thing, using a new bike built to challenge e-bikes, when employing my old 1980 or 1984 commuter bike race technique. Set the highest gear, get up and go full sprint. The average speed for the first test ride was around 25-30 km/h. That is not so bad given our landscape and my handicap and all.
Some images of that new acquisition and modifications: