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Wednesday, June 4, 2008

Got Sag??

Growing up, I was fortunate to have a neighbor, Kevin, that had a Kawasaki bike with rear shocks, similar to this Yamaha pictured here. Man was that thing neat! You could bounce up and down on the seat getting the plushest 3/4" of travel on the block! Only problem was, there wasn't another bike with rear suspension on the block to compare it to. Heck, there wasn't even another bike in town to compare it to. We'd heard rumors of a kid in Carlisle with one of the Yamaha's, but that was 6 miles away.... a lifetime when you're 11 years old!!

Fast forward to 1991. Always on the cutting edge, Cannondale releases its SE1000. What a beauty. I forget how much suspension this puppy had, but it was cool (note: there's a difference between cool & good). Too bad the rigid aluminum fork sent every rock, twig and other trail inconsistency into your wrists. Hey, at least your butt didn't hurt.... too much. Before people decided that this design wasn't all that great Hanebrink tried it's hand in the "rear suspension only" market with their effort, the Shocker.

In 1992, Trek released their full suspension bike. It's still debatable weather or not the rear shock was helping to smooth the ride (albeit only slightly) or the rear swingarm had so much flex it would deflect off rocks to make it "seem" like the rear end was working. Unfortunately, most of the time you realized you had rear suspension was during a long climb on a sunny fire road when the bike would inevitably "pogo" up and down robbing you of precious energy all the while.

In the mid to late 90's manufacturers would toy with different ideas. During this same time, I would leave my job at a bicycle shop in trade for a position as a suspension tuner at a motorcycle dealer. The area had more than a couple of really fun motocross tracks with my favorite being Doublin Gap. It was always easy to talk the boss into heading out to the track for some "testing" on our 1996 KX 125 shop bike. The shop sponsored some really good riders at the time as well including Jeff Yentzer who had a national #56 one year.... no easy task, trust me. This guy was FAST! During my time at the moto shop, I completed a 3 day seminar on suspension theory taught by Paul Thead who started Race Tech. You think I'm a tech geek? This guy takes it to the 5th power! I absorbed as much information as my little brain would handle in those three long days and continued to apply it to that beloved 96 kx125.

Through all of this, I was still mountain biking. It was the era of the earlier Marzocchi Bomber forks, they were orange back then. In my opinion, this is when bicycle suspension really started getting good. Marzocchi abandoned the "cartridge style" forks (like Rock Shock's magically exploding Judy's) and went for a system referred to as "oil bath". Manufacturers were still "tinkering" with rear suspension design and ideas, but Marzocchi had set the standard for what needed to happen in the front. Oil bath forks were a little heavier but the trade off was good reliability, constant lubrication and most importantly buttery smooth action.

Even with all of this, suspension on today's bikes is soooooo much better than it was in the late 90's. Manufacturers have come to terms on rear suspension with a few different designs that seem to be the best for our intended use. However, to get the most out of current suspension designs, the suspension needs to be set up properly. I was going to get all "fancy like" with some pictures and step by step instructions on how to get the proper sag for your bike but found a couple of good ones already on line. The most easy and basic is from Bicycling Magazine . They seem to get the point across without too much confusion. It's really not that hard, but oh so important.

The reason you want the bike to sag a little, is so the wheels can travel in BOTH directions. Even the poorest suspension set up will "give" when you push down on the bars or hit a bump at speed. The magic however, comes from suspension that's already sagged slightly allowing the wheels to "reach" DOWN into trail inconsistencies. Think of skiing through bumps completely straight legged (comparable to too much air/spring preload in your shock/fork) vs skiing through bumps with your knees slightly bent, allowing you to "push" the skis with your legs into depressions on the hill. Turn this theory into wheels on your bike and... VIOLA!!!

Personally, I like to run 20% of sag on my fork and 25% on the rear shock. This seems to fit the bill for my intended purpose which is xc/trail riding. The bike climbs well, has good small bump compliance and sticks like glue in the corners.... my favorite.

If you're still reading this, you either have a "cushie" job that allows you hours of internet surfing, your hurt (how you doing Shawn), or your independently wealthy like me (my dad invented velcro). If you fall into this category, head on over to First Flight Bikes to check out some more pictures from cycling's past. That website inspired this post.


Bender said...

Dude, I had one of those Yamahas! It was called the moto bike. And just think, it was parked just across the race from you every day in the summer. I do remember it being a shitty commuter, especially all the way from Gutshall Rd. I have no idea what happened to it. Kinda forgot about after getting my first Schwinn Thrasher. And by the way, I don't work in the summer.

Sarah said...

Great post! I found it very useful. Love the final result. Thanks for the inspiration and the tips.