It is well known that climbing is all about Watts per kilogram. This W/kg figure of merit almost completely determines a rider's finishing time on a given, steep climb. Reducing excess body fat is foremost important. Fat is not only unproductive weight, it increases load on the heart slightly and can make you run hotter. You want to reduce body fat to the point of maximizing your W/kg. You can lose some power with weight loss, but as long as you loss kilograms faster than Watts, your W/kg metric improves.
Only after you've optimized your bodily W/kg, should you get nit-picky with reducing bike weight. Weight taken off the bike is pure benefit, as you will lose no power when shaving bike grams. Your Watts per total kilograms is really what matters. Say you weigh 75kg and your bike, shoes, helmet and clothes weigh 9kg. Taking 1kg (2.2 lbs) weight off your bike might be an 11% reduction, which seems huge, but in terms of your total W/kg and net finishing time, it will shave only about 1.2% off your finishing time! Many don't understand this.
The whole rotational weight thing mattering on a 8-10kph hillclimb? It's a myth. Absolutely doesn't matter. I've commented on this before and won't go into details. Only total weight matters. There's no advantage in targeting wheels over other parts of the bike.
Currently, the UCI limits minimum bike weight to 6.8kg, or about 14.99 lbs. You can readily go into bike shops these days and buy rigs that weigh less than this. That is why you see power meters and physiological telemetry on riders in the Tour de France these days. The weight has to be made up, and why not with cool stuff instead of lead washers?
Riders have been getting pretty creative recently in mods for Mt Washington. There are no UCI rules there. The only requirement is you must have at least one working brake. I've never gone to extremes for hillclimbs. I haven't even invested in carbon tubular wheels, which could shave a half-kilo (pound) off my bike weight.
So let's take a look at some of the rigs that have appeared recently. We'll start with Cameron Cogburn's 2012 rig, which he propelled to overall wins in Newton's Revenge in July and the original race in August with a time of 52:28. Cameron removed the rear brake and front derailleur. You never need the big ring, except possibly for about 10 seconds at the start. At most, you might lose 1s by spinning out with only a compact small ring. Removing front derailleur, cable and shifter can net somebody like Cameron 10-15 seconds over the climb. Big net gain there. Same with rear brake. You can remove at least half a pound there, maybe saving another 10 seconds. So what Cameron did was replace the standard road drop bar with a carbon bullhorn bar. This saved a little weight, but bigger savings come by eliminating the road STI shift/brake levers and using TT front brake lever and TT rear derailleur shifter. Very minimalist approach, and now copied by several. Cameron is an astrophysics grad student at MIT, so you can bet he knows his shit.
Cameron Cogburn on his way to a win at Newton's Revenge in 2012.
The current 2013 BUMPS leader took note of Cameron's setup and took it a step further. Jason DeLorme replaced the road compact crank with an MTB crank with a single, tiny ring up front. Jason says this gets the weight down to 5kg (11 lbs) and change.
Jason DeLorme with similar setup to Cameron, except with stripped down crank.
In 2012, Bikeman took on a special project to build the lightest possible bike for Mt Washington. There was no limit to the amount of customization that went into the rig. The weight was reduced to 6.98 lbs (3.165kg)! I believe this was fixed gear, and that weight was with no brakes. I don't know if they attempted to ride it that way against the rules or not. Practically speaking, the only time a brake is needed is after crossing the timing mats up top, and even then, you are going slow. A fixie could easy stop soon enough. I would entertain something like this. I save over 20s per pound, and this bike weighs less than half what I typically race up Mt Washington. That would save me 2:40 off the clock! Of course, that assumes having one gear doesn't cost me power. My fastest time up Mt Mansfield was on a singlespeed MTB, so I do have some evidence that the weight savings trumps loss of optimum economy on portions of the course.
The sub-7 lb Bikeman.com wonder.
So now let's look at what I plan to ride this weekend. It is most definitely a frankenbike with parts gathered from here and there. I spent almost no money for this year's mods, using things I had laying around. I've always removed the front derailleur and rear brake for Mt Washington. One of the biggest weight penalties that remained was the heavy alloy drop bar and Shimano STI levers. I could cut over a half-kilo if I went with MTB setup. You see, even though I removed half the brakes and half the derailleurs, I still had 100% of the shifter and lever weight. I only needed half of each side. You can't split STI functions. So I replaced the drop bar with a flat alloy MTB bar from early years of mountain biking. It weighs about 140g vs 250g for drop bar. Then I used a Shimano XT rear shifter and Avid front brake lever. Each weigh half what an STI lever weighs.
Hill Junkie frankenbike. Flat bar with old-school MTB components.
For the drivetrain, I'm using a setup used multiple times in the past. I milled off the spider of a Ultegra crank and kept the 74mm BCD pattern for a 30t elliptic Q-ring. Since I wanted to keep the lightweight Dura Ace bottom bracket, the best one ever made with roller bearings, I had to mill down the 74mm BCD posts to get the chain line right. The ring is aligned with the third biggest cog, so it's biased toward the lower end of gearing range where you spend most of the time on Mt Washington. This improves drivetrain efficiency. In back, I use a Dura Ace 27t 9-speed cassette. I left the MTB XTR derailleur on there, as it weighs only 5g more than a Dura Ace road derailleur. Didn't want to have to change the chain length for one race. I normally have a bigger cassette on the back for other races. Note I keep the lightweight left crankarm on, a carbon FSA arm that is part of the compact crank I normally have on this bike.
Modified alloy Ultegra triple crank on right, FSA carbon on left.
There's not much else. I replaced the water bottle bolts with aluminum ones I happened to scavenge. That saves 10g for free. My front derailleur mount is removable on this frame too, so I pulled it off with its screws and covered the holes with electrical tape. That saved another 20g. The front derailleur cable adjuster on left side of frame was removed too. Many little things like these add up, but combined, might shave only a couple seconds off the climb. All of these mods got the bike weight down to 13.8 lbs (8.6kg). This is not bad with alloy clincher wheels.
Seat post tape may come off if no chance for rain.
What you can't see above is the inner tubes. Tests show latex has lower loss than butyl. I use only latex tubes for hillclimbs. Since most of the loss while climbing is rolling loss, improving the ~4% loss even a little bit can shave several seconds off your time.
I set a goal earlier this summer to establish a new personal best on Mt Washington. While recent performance numbers suggest this is a long shot, I'm not giving up hope. I'll be one pound less weight with the bike and near lowest body weight. The rest depends on weather and pacing correctly. My biggest short term concern is how badly my injured wrist is going to impact my performance. A flat bar may now well be an impediment. Hate to have to put the drop bar back on for a more comfortable wrist angle, or worse yet, mount bar ends. I'll have to get out in the next day or two to see how this setup feels.