Thursday, August 25, 2005

Dialing in HP

Went down to East Coasters to talk to CB about some bike fit stuff. These guys are Serotta Certified Fitters and know their stuff.

One thing that never ceases to amaze me is how small tiny adjustments can make a huge difference in power output and handling. Earlier in the year I worked with Wes at the Roanoke Store and he made some changes to my saddle that showed IMMEDIATE power improvements when I got on the ergo trainer later.

I've been riding for more than 15 years, and am also the type of person to tinker and mess around with position. And you'd think that I'd have dialed in a fit that I could take from one bike to the next. But I highly recommend to anyone, new cyclist to veteran of 20years to consider getting a fit done from someone who knows the Serotta system. It is based on your flexibility, something which I have very little, and not based on static measurements.

Fitting a mountain bike is a different than a road bike. The lower body setup is similar to place you in a power position. But because of the dynamic nature of off road riding, and the handling characteristics off road fitting the front end is not so scientific. Some people steer different than others, and stem length, rise etc have profound affects on handling between individuals. And unfortunately, Chris said that even at the Serotta school they don't spend a lot of time on mountain bike fits.

I'd set the bike up with a saddle height like my hardtail which was a tad lower than my road bike. My fore aft was still a little to the rear. On my ride yesterday, I tried to bust out a good climb on Old Farm single track and I was like a minute slower than my best time on the Salsa. I KNOW this bike is a more efficient climber but it just didn't seem like I was getting on top of the pedal stroke very well. I went for a short ride after the change to the saddle, and could tell an immediate difference. I was getting on top of the pedal stroke and just ticking a great cadence off and climbing awesome. Just amazing that such a small change had such an impact.

CB moved my saddle forward more and also tilted it to get my sit bones placed better on the saddle. Really really small changes, so small you had to measure to see them as eyeballing showed hardly any changes.

One thing he noticed was that my bars are pretty wide. My shoulders measure 40cm, and with the halfpipe shifters my hands are all the way on the ends of some wide riser bars.

This places a lot of stress on my upper shoulders and rolls my shoulders. I do notice really tight upper traps after rides. On my road bike they made similar changes to a narrower bar that immediately rotated my shoulders in and relaxed my upper body a lot.

He suggested lopping off like 1" on each side. that is big. With the riser bar, the bend in the bar really starts to limit how far you can move things inboard. And the halfpipe shifters are so big they limit how much room you have and were you can put you hands.

I've got some old bars at home I'm going to cut down and play with, but I may go back to a flat bar. I haven't been on a flat bar in like 8 years or something. The main reason with going with the riser bar in the first place was to get the bars higher for more technical riding, But with the highly sloping top tube of this bike, I am not going to have a problem with a flat bar, and I've got plenty of room on the steerer tube to place a flat bar high enough with spacers.


The bars are too high right now. I can tell when climbing that the front end is too light, and even though I like the on demand front wheel lofting, I'm having a hard time controlling it. The taller fork is probably to account for the raise in the front end.

Also the stem is too long, I can tell that it's harder to corner and lean than I want it to be. This is the same feeling when I had a too long stem on the Salsa.

Lowering the bars will help get some more weight on the front end which I do need because this bike seems biased towards the rear. Getting a shorter stem will quicken up the steering making it quicker in the single track. And a shorter bar will quicken it up, but also require more leverage.

I've felt the bar has been a little wide for me before, but kind of got sucked into that wider bar for burlier riding sort of marketing. My hardtail has a narrower bar and it didn't feel any worse to me.

Other things that need dialing in are the fork sag. The stock spring is for someone 150-170lbs. I'm at 135 or so. So I'm putting less air in the air spring in order to get the right sag. And the rearward bias of the bike makes me use even less air. The result is the fork is too squishy.

A soft spring kit would allow me to set the right sag but still keep the air spring pressure up making it stiffer and a better overall ride.

Regardless of these changes. I just cannot emphasize how happy

I am getting with this bike. One the three rides I've been on it just gets better and better. The pedaling of the
DW link that Iron Horse licensed is really amazing. It uses all the travel but still doesn't suck energy away on the climbs.

I don't want to get too comfortable or adapt too much on the current setup because some of the changes may be drastic. But it is just flying on the downhills.


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