MadRocketSci
new member
Reged: 02/18/04
Posts: 6
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Hey Kahuna,
I read your post over on velonews in defense of the Madone, and wanted to ask you about it over here...
Beware when measuring these bikes to fit, you will find the bottom bracket positioned further back than most race bikes. The center of the BB shell lines up with the rear edge of the seat tube not along the centerline of the seat tube. This has the same effect as steepening the seat tube angle. Sizing yourself on these bikes is a bit strange - especially when using KOPS as a starting point, which is probably why some people find the Trek feels strange to them. In my case, no other bike I've found works as well as the Trek does for me and I can hardly wait to order a Madone.
I'd like to know if you have your saddle set to a different position than your other bikes, and if it is KOPS, behind, or in front. I've read an article on the web that encourages moving the saddle forward and up for climbing, and was wondering if, by sizing for reach, trek is trying to get you a bit more forward of the bb for climbing. Here's the link to that article:
http://www.cranklength.info/climb.htm
Sooo...where is everyone putting the seats on their treks?
Thanks,
MadRocketSci
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Kahuna
Forum Admin
Reged: 12/11/03
Posts: 162
Loc: Maui, Hawaii
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MadRocketSci,
My saddle is positioned fairly centered on the rails. You can see a picture of the exact setup I'm riding on this website in the Production bike Photo Gallery. I don't know the exact measurement of the saddle position behind the bottom bracket in centimeters, but I do know it places my knee (tibial tuberosity) about 1cm behind KOPS. My kneecap is practically right over the pedal axle. On my other bikes, I'm further back.
The net effect of the more forward position is that I ride with what feels like noticably "more power" than my other bikes. I feel like I can push it harder and ride faster and with less fatigue than before. This is all very subjective since I don't have a true power meter to measure the difference in watts. For all I know it could be less watts knowing how bizarre things tend to work but for now, I feel very dialed in and happy on the Trek. I love the position and I wouldn't want to go back.
As for climbing. No doubt the bike's light weight (helped by the wheels) really makes a difference. Like most people, my position when climbing alternates between seated and out-of-the-saddle but when I'm sitting, I don't feel the need to adjust my saddle position. It just feels right.
Hope this helps.
-K.
P.S. Here's the same images I posted in response to c40's suggestion that I was wrong about the bottom bracket position on the Trek. As you can see by the red line that follows the angle of the seat tube, the center of the BB shell lines up with the rear of the seat tube, not along the seat tube centerline as it does on most other bikes. So the question becomes how does Trek measure (ie. report) their seat tube angle measurement - is it the actual angle of the seat tube, or the steeper, virtual angle - for example, as if you had left the red arrow pointing at the BB center but moved the top arrow to the center of the seat tube?
5900:
Same thing with the Madone...
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MadRocketSci
new member
Reged: 02/18/04
Posts: 6
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Hi Kahuna,
As far as how trek measures the seat tube, i think it's pretty clearly shown from their pdf file...
http://www.trekbikes.com/bikes/2004/pdf/2004_geometry_en.pdf
the angle is basically the angle of the seat tube wrt horizontal.
Based on your reply, it seems that you've kept your reach about the same, and this puts you a little closer to the bb than on your other bikes due to the bb-offset. Otherwise, you could just move the seats on your other bikes forward for the same effet...
is that about right?
MadRocketSci
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vaxn8r
contributor
Reged: 12/19/03
Posts: 222
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Somehow I know intuitively that you are right about how the Trek feels. I had a hard time explaining that I always felt more powerful on it than other bikes. But I always figured that I just had it dialed in perfectly. I set up my Tetra Pro to exactly (hopefully) mimic my seat position relative to BB with the "Trek". The front end I wasn't as concerned about. The end result is that I think it worked. I feel great on the TP. Good thing after laying out that kind of cash on a new ride 
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Allan
journeyman
Reged: 05/04/04
Posts: 198
Loc: Bds,W I
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Hello Kahuna,
I was looking at the postings for the saddle position and noticed that no mention of saddle set back to BB was included. While i do see the offset of the BB to the seat post C/L in the Trek frames, i found that personally there is a marginal area of about an inch that you can safely "play" with in terms of the actual position.
I know from my own experience that regardless of seat tube angle or BB offset, my comfort zone for a perfect position of saddle set back is 6 cm behind the BB axle centre, when i drop a plumb line from the front of the saddle.
Also there is the plumb bob test for the various areas taken at the knee(depending on the formula)so the line can pass through the pedal axle centre when seated on the bike,clipped in and the crank on the measured side at the three o'clock position.However in reality, this only gets you into the ball park area, then you now need to fine tune the rest.
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Its time to ride.
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