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Recreational Cyclocross and Gravelbiking This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like :The Dirty Kanza". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

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Old 02-17-13, 05:48 PM   #1
j814wong
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CX bike fitting without help from an LBS.

So my I have just bought a CX bike with partly my money and partly my parent's. I'll soon receive it from Bikes Direct. Does anyone have any guides to fitting it, saddle height, etc? I am confident that I purchased the right size bike (A 54 cm Gravity Liberty CX[SUP]1[/SUP]).
If I fail to get a comfortable fit, then I'll go to my LBS.

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Old 02-17-13, 05:52 PM   #2
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http://www.competitivecyclist.com/za...LCULATOR_INTRO

I used this when building my old road bike, it does a pretty good job. You'll probably need someone to help measure you, though.
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Old 02-17-13, 06:33 PM   #3
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Originally Posted by screamsayonara View Post
http://www.competitivecyclist.com/za...LCULATOR_INTRO

I used this when building my old road bike, it does a pretty good job. You'll probably need someone to help measure you, though.
Thanks. I take that the "road" option is appropriate?
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Old 02-18-13, 05:09 PM   #4
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Originally Posted by j814wong View Post
Thanks. I take that the "road" option is appropriate?
Correct.
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Old 02-19-13, 04:31 PM   #5
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Thanks a lot.
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Old 02-19-13, 04:52 PM   #6
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If you already have the bike, I wouldn't bother with something like an online fit calculator. The most that will give you is a starting point, and it might be a wildly inaccurate starting point.

Here's what I'd suggest:

1. Figure out the saddle height. Take a guess first just by eyeing it up. Then raise the saddle until your knee is slightly bent at the bottom of you pedal stroke. The fitter I just visited looks for a 30 degree angle in the knee, but you can probably just go with "slightly bent". If there's any discomfort in your pedal stroke then the height is wrong. If you find that you rock your hips as you pedal, it's too high. If you find yourself putting your knee out to the side as you pedal, it's too low. Beyond that, just let comfort be your guide.

2. Figure out saddle fore/aft position. The rule of thumb on this is that when the crank arms are horizontal your front knee should be directly over the pedal spindle. That isn't critical, and a lot of people use different standards. The main point here is that the fore/aft position of the saddle should be used to make the pedal stroke comfortable, not to make the bars easier to reach.

3. Figure out bar position. This is the tricky part to do on your own. Doing it right requires either a large collection of stems or an adjustable stem. For the most part you can go by comfort here too. If you feel like you're falling forward and leaning on the bars, you might need a shorter and/or higher stem (though this might also mean that your saddle is too far forward, but if you did step 2 right it shouldn't be). If you feel cramped, you might need a longer stem. If you're young and flexible there's probably a really wide range of stem positions that your body will tolerate.

4. Repeat steps 1-3 as needed. Don't worry too much about bike fitting rules. If something feels more comfortable to you, it's probably better for you.
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Old 02-19-13, 08:59 PM   #7
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Take data off the bike you have , you can measure that, aka 'cockpit' dimensions.

and then shop the numbers that you gathered, for comparison.



Saddle height , I use a yardstick , bottom end on top of the pedal spindle.

that takes in crank arm length.

Last edited by fietsbob; 02-21-13 at 12:41 PM.
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Old 02-21-13, 08:39 AM   #8
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I like Andy-K's method because of my own experience: Last summer I was trying to decide between a 2012 or 2013 model year Trek DS. They had completely redesigned the frame for 2013 and I found that the most comfortable frame for me was a 17.5' in the 2012 or the 19" in the 2013 ... But, my LBS was very confident that he could make either one fit just fine. Although he has all the fancy fitting stuff -- he mostly uses a method very similar to what Andy-K described. In actuality, an experienced one can eyeball a rider and adjust the bike to be pretty close without any measurements -- and before the rider has even sat on the bike...

I would do the manual adjustments as best you can and ride it a few times to see how it works and fine tune it. If you need to start playing with handle bar extensions and stems, that's a good time to head to the LBS because there you can probably save money by better avoiding the trial-and-error methodology.
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Old 02-21-13, 01:25 PM   #9
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You want a slight bend to your knee at the bottom of the pedal stroke (6 o'clock position). If your hips rock when you pedal bring the seatpost down in small increments until that stops happening.

Knee over pedal spindle at the 3 o'clock position is a good starting point for setback. Saddle should be level to start.

Stem length and angle are tougher. If this is your first bike with drop bars I'd start with the bars close to even with the saddle and ride the stock setup for a while. Don't angle the bars way back or anything silly like that. Make sure you can use all the hand positions available with the drop bars.

If you decide you want to make changes to where the bars are positioned, try to think about where you want them relative to where they are. The head tube angle of your bike, the length and angle of the stock stem, and the sizes of the spacers provided with the bike should all be easy to figure out. Once you have those numbers, use the "compare" feature here to see how repositioning your stem or swapping for a different stem would affect the height of the bars and how far away they are.

http://www.brightspoke.com/t/bike-stem-calculator.html

It will take some trial and error, but I find much easier than simply guessing, particularly if a new stem is needed to get my fit dialed in.
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Old 02-21-13, 07:30 PM   #10
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Thanks Andy_K. I'll start with the online calculator's "eddy" fit then proceed from there using your method.
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