Thursday, September 25, 2008

120psi awesomeness

Okay, let's do something totally random today. d:

Now if you have read my introductory "essay", you'd remember that I cycle practically everywhere over here, including to and fro work everyday. It is considered part of life here at Mountain View (a lot of people cycle, not as many as in Europe, but far more than in Singapore). Now for road cyclists, tires pressure is of utmost important. You should inflate your 19/23/28mm tires to at least 100psi. I'm quite conservative at that and usually bike at 105-110psi tire pressure, which feels okay. So today, I decided to be less conservative and pump the tires up to just above 120psi! That is actually more recommended for me since I have quite a heavy built (umm, just say fat!). You know what? The ride was awesome. The rolling resistance of my Vittoria Zaffiro Pro tires just dropped significantly. Cranking up the speed becomes so much easier, even on slight uphill.

It was a little scary! It's like the first time I got my roadbike and the first time I was speeding up above 20mph (that's over 30km/h). This morning, I definitely hit a new top speed (well, at least on flat road; on downhill, it is even scarier!).

Let me deflate my own happiness then. Having a high(er) tire pressure actually gives the illusion of you going faster. That's because more of the vibration caused by uneven road surface is channeled up to your handlebar and saddle. It made it seems as if you go faster when actually it's all illusion. Sigh. But the bit about reducing rolling resistance and actually going faster still holds true. The only way to be sure is to time yourself though (and lo and behold, I got faster by ~11%!

It wasn't just because of the increase in tire pressure. Over the past weekend, I've been busy hunting for parts and upgrading my bike. My hands were all oily and greasy (plus full with grimes), but the results worth all the hardwork. So what exactly did I do? I upgraded the front crankset and the entire front drivetrain!!

The old FSA crankset and chain
The old FSA compact 50-34T crankset (for sale) and chain. You can see the chain tool on top right, along with part of the chain cut from the new chain.


Originally, I had an FSA Energy compact crankset with 2-gear 50T and 34T (along with Shimano 105 front derailleur). It was noisy and it was horrible on an uphill. 34T is not small enough on steep uphill (especially on a fat person that is me). I had to constantly pump and waste energy when going uphill. Bad. So I decided to upgrade to Shimano Ultegra triple crankset! That is, one that provides me with 52T, 39T, and 30T! That means I had to upgrade the crankset, front derailleur, and the chain! Yes, it was an expensive upgrade, but it was all worth it.

With the new 52-39-30 combination, I could ride on a flat road at faster speed and better gearing ratio (with the 39T, middle gear), on a downhill, 52T gave a really good gear (and much faster speed, those 2 gear teeth gave a little extra speed, but coupled with downhilling, it's just much faster now). Most importantly, the 30T! Yes, the so called granny ring (demeaning I know, but who cares, I can conquer more hills with the "granny" ring) enabled me to go uphill much better than before. No pumping. Just constant spinning (pedaling as fast as you can). It doesn't build strength as much as the larger gear, but it gives a good aerobic exercise.

The new Ultegra front drivetrain
The new ultegra crankset with the derailleur just above it (top); top view of the triple crankset, you can see the three chainrings with the chain currently at the lowest gear (bottom).


Now the Shimano Ultegra 6603 series front drivetrain (consisting of the crankset and the front derailleur) was enamoured further with Shiman top of the line Dura-Ace chain (and the stock Dura-Ace 10-speed rear derailleur). The chain rotates so smoothly that it was quite eerie riding it the first time, especially after hearing day in day out the noisy FSA crankset's friction with the old chain. The 10-speed real derailleur gave me a total combination of 30-gear! Now that's something. Not that I need all of them (I haven't touched the smallest 5 gears and the largest 3 gears ever). The only combination that gives more gearing is Campy 11-speed rear derailleur coupled with triple crankset (33 gear! wth!!).

Oh, and btw, mechanic-ing your own bike is fun! If you have a bike of your own and want to upgrade or replace parts of it, try it yourself! Ask your bike shop's mechanics for some pointers and read online (and get the right tool!). Sheldon Brown's website would be a great place to start.

-Chris

2 comments:

Dienasty said...

THAT was one of the most surreal experiences I've ever. =) Reading a blog post about bicycle tires in a compsci blog sure takes the breath out of you lol =)

chris said...

Thanks! I really love biking. Though it's a pain to bike in Singapore with the weather and the traffic. ): Plus the needs to cross-training is annoying... (the maintenance, contrary to expectation, is pretty fun!)

(: