Christopher's Bicycle

Christopher came to me with something of a challenge.  He wanted a bike for ‘audax and general riding around enjoying the view in whatever weather’ riding.  He also wanted it to be ‘ as close to zero maintenance as possible’.

As ever we started out by getting an appropriate riding position sorted. Christopher has a long back relative to his height which has always caused issues with either comfort and/or handling of bikes in the past. I addressed this issue in the design so that the frame has a particularly long top tube, paired with a custom made stem to reflect his upper body proportions and keep the steering geometry appropriate.  

The top tube has a steep slope to provide ample standover height and the bottom bracket is low which helps with both handling, a lower saddle-ground distance and correct saddle-bar height differential without needing forks with an abnormally long steerer tube.  The geometry is very much for audax riding: Handling is very stable and predictable optimised for the speed that Christopher averages on most of his rides.

In order to address the zero maintenance request I designed the frame around the ‘Pinion’ internal gearbox system.  This provides 18 gears which are evenly spaced at 10% intervals and give over 600% total range!  The system is designed primarily for MTB and touring use so I stepped the gearing up a little so that the ratios reflect the gear lengths that christopher is well used to  (with a few extra ‘bail-out’ gears!).  I chose this over a hub-geared system to keep the weight distribution of the bike better balanced:  So despite it adding some weight to the total package this should have a negligible influence on how the bike feels to ride. I used a carbon belt to provide drive in place of a traditional chain which again removes regular maintenance tasks.  We opted for mechanical disk brakes which, paired with some polymer coated cables, provided the best compromise between low maintenance whilst remaining familiar enough for Christopher to work on them himself as needed.

The frame has been built using a mixture of Columbus steel tubing and a Sturdy Cycles carbon fibre integrated seat mast.  The mast has been designed and made specifically for this bike.  This solution was chosen as it removes the often troublesome, and in my mind unnecessary, interface at the seat tube/seat post junction.  A steel seat mast would have had to be reasonably thick wall to avoid buckling failure which would have added unnecessary weight and been detrimental to ride quality.  

The custom covered saddle is mounted via a mast topper that I made to suit which provides enough adjustment for position tweaks. We wanted to keep his riding position as similar as possible to on the hoods of his drop bars. I modified some ‘bull horn’ bars to provide a nice comfortable platform in a very similar position.  The rotary shifter is mounted to the custom stem in a position that is easy to access with minimal ‘hand off bar’ movement.

Christopher was keen that none of the fillets were cosmetically dressed after brazing and wanted un-fussy straight lug-lines; he wanted to be able ‘to see how it was made’ and ‘let the paintwork do the showing off’.  He chose a green theme for the bike and then let me run with it, I am pleased with the result!

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