Stranger than quantum physics

One of my favorite authors, Terry Pratchett, would, tongue in cheek I suspect, use the word quantum for any aspect of science that just seemed weird. Quantum physics, as described by Caltech, is the study of the really, really, really, and many more reallys small bits that make up the merely really small bits we can see. Things that little end up behaving in a rather odd fashion when viewed from the perspective of our scale.

Bike parts are big and function in the realm of Newtonian physics, but it seems the bike industry was bored by anything so humdrum, thus was born the more bizarre world of bicycle physics. Under these laws, a concept needn't be actually true, it just needs a compelling false explanation, and most importantly, marketability.

One of my many long standing gripes is stems that use bolts other than the 5mm hex head of a headset top cap. I like needing only one 5mm wrench to adjust my headset, or even swap the whole stem, although I give a nod of approval to Kona who produced a top cap using a 4mm head bolt to match the stem they specified. They may have even saved a half fart's worth of weight by using those small bolts! Grumble, grumble, please excuse my belly.

Different bolt sizes, while annoying to me, could be justified as being just the right size for the load in their location, but the bolts on the stem on the bike on which I rode Friday and Saturday annoy me without any justification within my understanding of physics. The two bolts clamping the steeerer are on opposite sides, forcing the mechanic, who hopefully has the training to tighten the bolts progressively back and forth, to swap the wrench awkwardly left and right, repeatedly. I'm certain the explanation is that this applies equal force to both sides of the stem, but that is true even of less cumbersome designs. Bolts provide a given tension along their length no matter which side fits the tool.

No!

So fiddly stem bolts are annoying, but at least they're not functionally problematic. For that, I'll look to the bike I bought a few weeks ago for the really cool internally geared hub that I'll transfer to another frame that actually fits me. Specifically, I'm looking at the seat collar clamp and the slot in the frame that allows the seattube to clamp the seatpost. They were on opposite sides. I've seen this before and heard the explanation that by having the clamp of the collar over a solid part of the frame, and vise versa, the slots, a "weak point", are reinforced by a section of solid metal. But that "weakness" is intentional! It alows give in the clamp and tube to clamp on the seatpost. Trying to clamp the slot of the tube with a solid band of clamp requires much, much more force on the clamp that is 180° out of alignment. If reinforcement is needed, let the solid full circle of seatpost do that.

I thought about spinning the clamp back

180° out of alignment

for this picture,

but I just refused to do it!

This is not to say people in the bike industry never get physics right. Try riding one of Dave Weagle's full suspension designs set with the right sag for your weight and prepare to be amazed. I took a quick spin around a flat field on one of his old 8" travel downhill designs, and it sprinted really well. Done right, physics works!

I'm also a huge fan Keith Bontrager's article about bike fit. I met him years ago, possibly at the same mountain bike festival where I tried the Weagle DH bike, and thanked him for writing it. He started cautiously defensive, as I don't doubt he has caught flack for opposing the standard dogma of bike fit, and asked me, "Did it make sense?" I replied, "It's the first thing I've ever read about fit that made any sense regarding physics!" We talked a little more before I had to excuse myself to teach a clinic, but I later heard from one of the event organizers that he appreciated meeting me enought to mention it later. Fun detail about Keith I once read: He went to school for engineering, but knew he planned to work for himself, so he wasn't concerned about presenting a degree to an employer. He took just the classes he needed and skipped everything else. That gutsy to a degree, or lack of one, I truly respect.

The nicest bike

I ever bought for $40.

I need to build and ride it!