During the 1970s, with a very limited knowledge of bicycle design, I produced several fantasy drawings of my ideal off-road bicycle. All included a high bottom bracket for better ground clearance.
The reason at the time was simply practical. I had discovered with the actual bicycles I was riding cross-country that my pedals were far too frequently hitting obstacles, or my chainwheel would get stuck when trying to get over a fallen tree, for example, often preventing me from successfully, fluidly and efficiently riding through tricky terrain, limiting where I could ride.
Back then there were no mountain bike trails and far fewer off-road paths as we know them today; many a right of way may have been marked on the map, but on the ground it could be indistinguishable from the surrounding countryside. Tricky terrain was unavoidable.
Posted by jasonl
Was lucky enough to meet Geoff and ride his bike prototype a while back. A couple of us fat bikers took him to the local beach and rocks.
The day was mostly Geoff wanting to find more and more extreme obstacles to attempt, so we also rode over some large tree felling brashings.
Even today, with plenty of well-maintained paths around, avoiding tricky terrain still limits where you can ride. In Scotland off-road cyclists have the big advantage of ‘Freedom to Roam’. Here, where I live in Berwickshire, we have a very low population density and a minimal demand for well-maintained paths. Further afield, the Scottish Borders boasts world-class mountain bike trail centres.
To go and ride these trail centre routes requires at least an hour or two’s driving time just to get to the to the trailhead. If I have only an hour or three to spare it’s just not practical. This applies to many off-road cyclists; often there is riding potential close to home. Only if you can connect rideable trails with sections of tricky terrain, do you get a substantial and interesting circuit.
So, way back then, whilst I recognised the need for ground-clearance, I didn’t know you must have your saddle at a height that allows your leg to be almost straight when your pedal is at its lowest. As fantasy and practice converged, I realised I was either going to have to sacrifice ground-clearance, or have my saddle so high I couldn’t easily reach the ground, and an even higher handlebar.
I agonised over this a lot, until eventually cobbling together a bike utilising the frame from a Raleigh ‘Twenty’ shopper bike (above), from which I removed the brake bridges. With longer front forks I could fit 26″ wheels and the bottom bracket was thus raised to about 14″.
It looked something like this and was, as a whole, a bit of a dog’s breakfast. It did, however, reveal to me that riding high is more than OK, even if at that time I had no intellectual understanding of the role of centre-of-gravity in keeping your bicycle balanced and steering.
Over these years of research and riding, I’ve concluded something that nearly everyone else will think is utter nonsense.
Until they’ve read the next few pages.
Click here to go to the beginning of the whole story.