Alliance Bicycles

Warning: Extreme Bike Geekery Ahead

I have received a few questions about the style of bike I’m taking to NAHBS.  This type of bike is usually called a dirtroad bike, all-arounder, or a rain bike.  A lot of what defines this bike is builder dependent, however suffice to say, it’s much more than a cyclocross bike with fender mounts.

• In general, the bottom bracket will be in line with a classic road stage race bike, around 70mm-80mm of drop.
• This lowers the rider’s center of gravity which increases stability when riding smooth tires on gravel roads.
•  The chainstays will be shorter than a cross bike, but longer than that of a road bike.  Mine are 420mm which is enough to clear fenders and tires, but still keep the wheelbase in check.
•  To counterbalance the longer backend, I slacken the head tube angle to 72.5 degrees and increase the fork rake to 46mm.  These two things maintain the handling characteristic of a normal road bike, but keep the rider centered between the wheels for even weight distribution.
• This provides a trail measurement of about 59mm with the appropriate tires, which is typical of a road bike.
• The slacker head tube/increase in fork rake combined with the longer chainstays help soften the ride on rough roads.

The most common tire size I see ranges from 24c to 33c.  This type of bike is also fitted with fatter 650b wheels if the rider desires more comfort.  I could also see shorting the cockpit  or raising the handlebar for a more upright fit. 

Brake style is also rider dependent and will vary between caliper, cantilever, or disc.  In the past I’ve always used canti’s, but I prefer longer reach calipers for both their aesthetics and lack of maintenance.  Cantilevers tend to work themselves into a squealing frenzy unless you constantly readjust the pads for toe-in.  For the most part, I find this to be true when it’s wet or cold and under hard front braking.  Not so much if its dry and hot, but that’s not when I ride a bike with fenders on it.  I also find calipers to have a firmer lever feel, but if maximum tire clearance is needed, cantilevers work best. 

Disc brakes provide the best braking in poor weather.  I have used them as well, but the pads have to be set close to the rotor because road levers don’t pull very much cable.  Even with the Avid road specific BB7’s, the rotors have to be perfectly true or the pads will rub.  Disc brakes add a fair amount of weight and look out of place on a road bike to me.

In my experience, you will out brake the traction of a road tire before running out of stopping power, regardless of brake used.  This is not true if conditions are excessively wet or muddy, in which case, disc brakes are appropriate.  See below for photographic evidence of the fine dirt roads that surround Bozeman.

No news on the framebuilding front because I don’t have any tubes to build frames with right now.  All of my funds were sucked into the vortex called NAHBS, so I just practiced welding on some seat tube cutoffs and such.