Odds and Ends - the Devil in the Details
Reporter: "Then how do you explain your popularity?"
Ringo: "Maybe people like adequate music."
Like the Beatles, a bike is greater than the sum of its parts. Many parts are obvious - the frame, wheels, chain, handlebars, seat etc, but there are a few parts that tend to be overlooked, yet contribute significantly to the function and form of the bicycle.
Consider the headset. Integral to the security of the headset is the tensioner bolt. Most headset, including the one bought for this build project, come with the standard star-fangled nut. This is an alloy disc that has been cut radially, and each section bent out slightly to form a shallow cone. As the bolt running through its centre is tightened the disc expands against the inside of the steering tube, anchoring it securely through radial tension against the tube. Further tightening of the bolt then draws the headset down towards the top of the steering tube.This works wonderfully if the steering tube is steel or alloy, but if you have a carbon steering tube the star nut is trouble. The outwards radial tension is concentrated along the edge of the disc, creating a zone of weakness that can cause the steering tube to fail. This will not necessarily cause a face-planting crash, but it will destroy the fork unit, possibly the headset, and also the head tube. If the head tube fails, you need a new frame.
The solution is an expansion plug. This is simply a smaller analogue of the old quill stems. Tensioning the headset bolt draws a cone bolt upwards into the plug, forcing its sections apart against a matching length of the steering tube. So, instead of the tension force focussed along an edge, it is spread over a 30 mm length of the inside surface.They are easy to find. The unit that I bought was the Prestine plug from the ebay trader teamssx. The total cost to me was NZ$16.46. Also from the same trader (same purchase order!) I bought a seat post clamp.
For many decades seat posts were secured by a bolt threaded through a flanged edge to the slot cut in the top of the seat tube. Many cheaper steel bikes still use this system, as it is simple to create, and it is integral to the frame. Also, home mechanics can maintain their kids' bikes by replacing lost bolts with any bolt that fits through the hole.
Modern bikes are made with a simple slot in the top of the seat tube, and the clamp sits on top of the tube. For bikes where weight is not an issue a quick-release bolt is used to tension the clamp, but I have chosen a hex-head bolt. The clamp provides tension that is distributed more evenly around the circumference of the seat tube than a quick release bolt, helping to preserve the integrity of the carbon seat post.Ribble came to the fore for most of the remaining pieces. These begin with the front derailleur clamp.
The front derailleur can be either bolted onto the frame, or clamped. many frames are constructed with mounting studs integral to the seat tube, and it can be difficult to mount a clamp-on derailleur unit to a flattened stud mount. Not knowing what frame I would end up with, I had bought a bolt-on derailleur. if, as is now proving to be the case, the frame does not have the studs integral to the frame, you can buy a clamp which has a bolt flange for securing the derailleur unit.
This CSN unit was NZ$12.45, and came with the headset spacers, 10 mm alloy rings that provide extra height to the stem. To secure the headset-stem-fork system the steering tube must be cut to the right length. Once cut, cannot be uncut. By trying different arrangements of spacers and stem you can find the right stem height for your riding style and comfort before committing to the final cut. I chose alloy spacers, as carbon rings can compress slightly over time when the headset is tensioned, so your initial setting will gradually change as the rings squash. The three 10 mm alloy spacers cost NZ6.74.
Handlebar tape is one way that riders can personalise their ride. With tape being changed at least one every couple of years depending on usage and crash damage, a rider can change the colour and pattern of the whole front end of the bike. Black is always safe, and doesn't show grease. White tape does. Titanium is a grey metal, and blue works with grey, so the Deda dark blue cork tape (NZ$15.29) is a good choice.
The last piece in the parcel is one which is rarely seen or even thought about. The cable guide is secured to the bottom surface of the bottom bracket tube by a single screw. Yet, it holds in place the cables for both derailleurs, and provides a smooth surface for the cables to move against. And here is a touch of Italian - despite using Shimano components, the best deal I found (at Ribble) was the Campagnolo cable guide, for NZ$7.06.
For bikes, as with many other machines, it is only when you start looking closely at one that you begin to appreciate how many parts come together, and every bike has aits own, equally important function without which the operation of the machine will suffer, if not be severely compromised. As with life, the devil is in the details.
