28 August 2008 - 14:39Weight Loss for Jets

So over the last few months I have had my Jet 9 set up as a trail bike, a do all, go anywhere sort of ride. I had initially set it up with some fairly beefy wheels, Royales with Flow rims, and great big Schwalbe Racing Ralph 2.4 tires. This was all about finding where exactly the Jet fits in my stable, while retaining a level of comfort and familiarity with a similar set up to my RIP.

The Jet more than proved itself on the big road trip south. I found it to be a very capable machine.It begged to go faster than I had gears for on the buff singletrack of Pisgah and north Georgia. it flew over the ground when the trails got ugly and rough. It shot around corners like a comet shoots around the sun. It descended like a bike with more travel than it actually had. 

All in all, this bike is a clear winner no matter how it’s built.

So, now is the time when I can build the Jet as I had always intended it to be, a race bike, knowing I can depend on it in just about all but the ugliest of scenarios.

The original build came in at 28.21 lbs, ready to ride (with pedals that is). Not that light really, but totally acceptable for a FS trail bike in my book. The single biggest beneficial weight savings was to be had by changing the wheels and tires to a more svelte set up, and I chose a set of Industry 9s laced to Stan’s Arch rims.

Bling!

I had to seriously think about my tire choice. Having destroyed the rear 2.4 Racing Ralph on a sharp mystery object, it was time to maybe think about getting something a little more appropriate for the bike. I had originally thought about a Maxxis Ignitor front and WTB Vulpine rear, which would be a very fast rolling combo, but with our weather, the rear tire could be something I’d have to change all the time. I’m lazy, so that option is out. I looked at the Karma 1.9. Both Jay Pro and Nat has been singing praises about this tire, but lets face it, Jay is about 155lbs, Nat is 175lbs, and I’m 225. Nope. I need more air volume under me. The next lightest tire I could find with decent volume was the 2.25 Racing Ralph. I am already a big fan of the tread pattern, so it was a no brainer to switch to the skinnier version of the same tire I’ve had on the bike all along.

They roll fast, are predictable when they break loose, and have good bite on our local trails.

I also took the time to switch the cranks from the “all mountain” double set up of the Truvative Noir, to a set of XTR M970s I’ve been sitting on all summer. The gearing changed from 24-36 to a 22-32-44. I measured 1/10th of a pound savings, even after picking up the third chainring. 

So with the wheels, tires and cranks swapped out, the new weight is 26.98. That’s a savings of 1.32 lbs of rotational weight. This is a pretty significant loss, and I’m pretty happy. I suppose if I tried really hard, I could probably get below the 26 lb mark, but then I’d have to compromise on some parts that I’m already quite comfortable using. To me, it isn’t quite worth it. Considering that I’ve already lost the most rotational mass I can safely get away with, I’d call this project done.

I managed to sneak out for a quick ride on it, climbing up to the top of Perry Hill from the shop in just under 30 minutes. I noticed that the bike was much easier to climb. Not only did I feel the lack of  weight in the wheels, I appreciated 2 less teeth on the granny ring. The wheels are stiff and spun up very quickly, and, looking down at my blue spokes, I felt like a million bucks. I’m pretty sure I’ll be getting another set of these wheels in the future.