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Transmission / Re: Matching sprocket and chainring to your cadence and heart rate
« Last post by Andre Jute on Today at 12:19:32 PM »One advantage of a front wheel hub motor is that you then have a 2 wheel drive bike, which can be useful in slippery conditions.
That's so true. I discovered twenty-odd years ago that my Gazelle Toulouse, a Dutch "vakansiefiets" (holiday bike, essentially a luxuriously fitted out commuter, too smart to leave at the station) had built-in ABS braking from the imbalance between Shimano's -43 limp rear roller brake* and a front disc brake. Nuanced brakes enabled me to set my personal downhill ton-up record on a steep downhill with a curve near the T-junction where the braking zone came to a sudden stop and step off the bike without breaking sweat, cool as a cucumber. (And the Gazelle's proprietary Switch stem, which could be set downwards, with reversed sit-up-and-beg bars, to put my back absolutely straight. The effort was also enabled by a truck, modified to suck out the air in front of me to tow me to the brow of the hill, where it pulled off before my measured run.) The pseudo-ABS enable me to brake much later and very smoothly, and come to a dead stop at the T-junction rather than go into the thorny gorse hedge across the road, for which I was prepared by wearing tight motorcycle racing leathers and helmet with a visor and HANS (a neck and head support). The limp, long obsolete -43 rear roller brake never once locked up and started sliding during the single run it took to reach a ton and change.
When I fitted the front electric motor, which I viewed as an educational tool, the impression was sharpened and reinforced: the limp rear of the bike nicely balanced the urge of the front motor and I never suffered a front washout from the extra weight in the front of the bike. Low learning curve.
*How do I know the -43 rear roller brake on the Toulouse was limp? Well, between the Toulouse and the Utopia Kranich with the hydraulic rim brakes, I acquired a Trek "Smover" which Trek Benelux had developed into a super-vakansiefiets with automatic gearbox and electronic active suspension, including front and rear the latest super-strong series -75 roller brakes, which were definitely not limp. In the end I came to hate them as requiring too much of the rider's attention even at the slow speed of a social ride, and at high speed they were more of a threat to the rider than the potholes, which really says something!
When I fitted a mid-motor to a newer bike, which had other advantages, I lost the ABS trick because it didn't occur to me in time to fit the then-available less strong Magura hydraulic rim brake at the rear and the strong one at the front, instead choosing the less strong -11 (today only cosmetically different from the more expensive -22) at both ends of the bike because I'm not a commuter riding between cars that may suddenly stop, but needed security from over-strong brakes or over-sudden brakes putting me in the ditch or over the handlebars on the curvaceous fast but rough downhills.
The regulars probably know what these bikes and components look like; passersby can see these bikes, including close-ups of the Shimano roller brakes and Magura rim hydraulics, at http://www.coolmainpress.com/BICYCLING.html
As an aside in keeping with the subject of this thread, a front motor lets you keep your favorite chainring, whereas a central motor is likely to require a dished chainring if you want to keep a straight chainline, and the dished rings may need more teeth to fit over the motor. For those of us who loved the 38x16 transmission, this could cause complication and expense because both chainring and sprocket may have to be changed to keep the transmission ratio the same as you're accustomed to. If on top of that you're a Chainglider aficionado, that adds a further layer of complication -- for a solution, check Martin's installation described above using the non-Rohloff Chainglider sprocket cover to custom-tune the transmission ratio. I didn't find this a big deal because previous unassisted cycling had made me relatively fit, so with the centre motor I replaced only the chainring with an inexpensive dished steel ring (I have good experience of steel chainrings, which I can't say for aluminium), and left the sprocket in place complete with the approved sprocket cover, and simply bought a new front Chainglider section, and presto! the chainline was not disturbed. I wish you the same luck!
