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Old 09-23-2012, 04:47 AM   #1
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How Much Adjustment Can Be Done?

With the help of my wife, I did all the measurements listed for the Fit Calculator on the Competitive Cycling website. Armed with the information it produced as a result of those measurements I looked at some bikes and their geometry. What I am finding is that the numbers for Fit Calculator dont seem to translate universally to bike geometry provided by manufacturers. So I have two questions here. I will provide below what the Fit Calculator produced below as well.

1. How much adjustment is there in a bike (road bike specifically)? That is to say, is the goal to be in the 'ballpark' with frame geometry and then fine tune it? Or should I get as absolutely close as possible.

My thinking on this, and I am not riding at this point, I am looking to buy a road bike and am just trying to educate myself, is that I would want to be in the middle. That way I have adjustment each way, but again, this is just reasoning on my part.

2. What measurements are most important?

Ive seen some indicate that stand over height was the more critical, Ive seen other information point more to the seat tube.

Here is my information as provided by the Fit Calculator. All are in Centimeters

Seat Tube Range, Center-Center: 54.5 - 55.0
Seat Tube Range, Center-Top: 56.2 - 56.7
Top Tube Length: 57.6 - 58.0
Stem Length: 12.2 - 12.8
BB-Saddle Position: 72.0 - 74.0
Saddle-Handlebar: 58.0 - 58.6
Saddle Setback: 7.2 - 7.6

When I was at a LBS a few days ago, they had me stand over a 54cm bike. I had maybe an inch or inch and a half of clearance between me and the bar. I also stood over a hybrid that I was told was an xtra large (56cm) and it was, ummm, going to be problematic.

Ive seen some generic size indicator (based on ones height) that say I need as big as a 58cm. If I judge that by my experience at the LBS, a 58cm is going to be shoving things up into places I dont want them. But the size indicators based on height seem to be all over the place and its hard to get a good feel for what I actually need.



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Old 09-23-2012, 04:51 AM   #2
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Let me add another question to this if I may.

3. How does 'compact frames' and 'semi-compact frames' affect what I need in a bike size?



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Old 09-23-2012, 05:16 AM   #3
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From a mountain bike standpoint, I used to always look at standover first. But now I have a frame that I cannot flat foot, and it's a great fit. In a crash, I may not be so happy. You just learn to lean at stops.

Top tube length is probably more critical. Your seat should only be adjusted fore/aft to get you in the most efficient pedaling position. That leaves stem length to accommodate your physical size. But longer and shorter stems affect your steering. So you want to get as close as you can to ideal fit with your frame, then fine tune with the stem.

At least, I think that's how it is these days. At 20, I would just jump on the bike and ride.

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Old 09-23-2012, 01:50 PM   #4
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I'd say not to get so hung up on numbers. Pick a few bikes, ride them and see what feels good. All the numbers and fit calculators in the word don't mean sheet if it doesn't feel good and you don't ride

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Old 09-23-2012, 01:56 PM   #5
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Sounds to me like you have figured out the reason it pays to look and ride those you are interested in! You now know that if you take to bikes from different brands, each in the same size, you are going to see differences in how the feel and ride. This is why the LBS is a good place to go!

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Old 09-23-2012, 02:32 PM   #6
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When they figure out frame size and stem length, the next step will be feel. What feels good? Like hack said you don't want to have to move the saddle for and aft, but rather adjust with stem and bars.

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Old 09-23-2012, 08:41 PM   #7
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1. Get the closest fit you can, but no matter what, you are going to have to adjust something. That's why seat posts are designed to adjust up and down, and saddles are designed to slide fore and aft.

( Edit: I should have added that saddles move fore and aft to adjust your the position over the pedals, not to adjust reach to handle bars.)

2. I'm going to join most bike manufacturers and biking organizations and recommend that minimum standover height is the most fundamental measurement.

If your pubic bone doesn't clear the top tube when you straddle the bike, you're in for really big time grief if you ever have to stop quickly, or unexpectedly, or on uneven ground. The League of American Bicyclists recommends the minimum standover clearance between the top tube and your pubic bone should be 1 to 2 inches on a road bike and 3 to 4 inches on a MTB. If you need to change reach a few cm, you can always get a longer/shorter stem.

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Last edited by LarryM; 09-23-2012 at 08:46 PM. Reason: added note on fore aft seat movement after point 1
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Old 09-24-2012, 09:52 PM   #8
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Thank you all for your input and help.

Larry, thank you for the details as well. That helped a lot actually. Particularly the clarification about the seat and the relation to the pedals.

Having given those details, I would like to learn a bit more. I want to emphasize I want to learn because my foray into beginning cycling has been dismal when it comes to the availability of good information and resources, locally anyway. I want to learn what I can so that if someone else has the questions I have had or do, then I can at least answer them in some educated form.

I have been in technology related fields for nearly 25 years. From electronics, communications, to now more network related work. So I tend to be technical in my explanation of things, but I understand not everyone is like that and try to have the understanding that allows me to articulate that technical understanding without necessarily all the mumbo jumbo technical jargon.

To that end, I want to understand more, the adjustments available to a road cyclist. You mentioned the seat is the adjustment of the seat is for the adjustment in relation to the pedals.

So I assume the height adjustment is so that your leg is extended near maximum so you get the greatest torque or push into a pedal. I would further assume then, the fore and aft adjustments as you mentioned, to get you centered over the pedals is so that there is no wasted effort, that is your legs are moving up and down in the pedal cycle rather that an angle, correct?

You mentioned that the stem is where you would adjust for your reach to the handle bars. I know the stem adjusts, as do the handlebars, up and down. What exactly then would one change those adjustments for?

Lastly, and sorry for the long winded post, what other adjustments are there that could be made and what indications would there be that that particular adjustment needs to be made?

Thanks for putting up with me, LOL.

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Old 11-01-2012, 04:24 AM   #9
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Quote:
Originally Posted by StormStrikes
With the help of my wife, I did all the measurements listed for the Fit Calculator on the Competitive Cycling website. Armed with the information it produced as a result of those measurements I looked at some bikes and their geometry. What I am finding is that the numbers for Fit Calculator dont seem to translate universally to bike geometry provided by manufacturers. So I have two questions here. I will provide below what the Fit Calculator produced below as well.

1. How much adjustment is there in a bike (road bike specifically)? That is to say, is the goal to be in the 'ballpark' with frame geometry and then fine tune it? Or should I get as absolutely close as possible.

My thinking on this, and I am not riding at this point, I am looking to buy a road bike and am just trying to educate myself, is that I would want to be in the middle. That way I have adjustment each way, but again, this is just reasoning on my part.

2. What measurements are most important?

Ive seen some indicate that stand over height was the more critical, Ive seen other information point more to the seat tube.

Here is my information as provided by the Fit Calculator. All are in Centimeters

Seat Tube Range, Center-Center: 54.5 - 55.0
Seat Tube Range, Center-Top: 56.2 - 56.7
Top Tube Length: 57.6 - 58.0
Stem Length: 12.2 - 12.8
BB-Saddle Position: 72.0 - 74.0
Saddle-Handlebar: 58.0 - 58.6
Saddle Setback: 7.2 - 7.6

When I was at a LBS a few days ago, they had me stand over a 54cm bike. I had maybe an inch or inch and a half of clearance between me and the bar. I also stood over a hybrid that I was told was an xtra large (56cm) and it was, ummm, going to be problematic.

Ive seen some generic size indicator (based on ones height) that say I need as big as a 58cm. If I judge that by my experience at the LBS, a 58cm is going to be shoving things up into places I dont want them. But the size indicators based on height seem to be all over the place and its hard to get a good feel for what I actually need.
If you are able to, a retul bike is awesome. About as accurate as you can get for a fitting.
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Old 11-07-2012, 01:05 AM   #10
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So I assume the height adjustment is so that your leg is extended near maximum so you get the greatest torque or push into a pedal. I would further assume then, the fore and aft adjustments as you mentioned, to get you centered over the pedals is so that there is no wasted effort, that is your legs are moving up and down in the pedal cycle rather that an angle, correct?
-- you want your leg to extend to about a 10 degree angle, not completely straight. Completely straight is bad for your knees. Your legs going up and down sounds logical to me to not waste energy. I know that if you drop a plumb bob from your knee cap down the pedal, it should be dead over the middle of the pedal to make your seat centered when the pedal is horizontal and in the downward stroke of the rotation.


You mentioned that the stem is where you would adjust for your reach to the handle bars. I know the stem adjusts, as do the handlebars, up and down. What exactly then would one change those adjustments for?

-- the height of the bars is one i have to read about still but i imagine its to keep your trunk at a certain level while your legs are at the proper angle. i know the reach on the stem is supposed to be at the point where when you are leaned into the bars the stem and handle bar block your view of the hub on the front rim. that is supposed to be the proper length stem.

Lastly, and sorry for the long winded post, what other adjustments are there that could be made and what indications would there be that that particular adjustment needs to be made?
--i know the pedals can be spaced outward from the crank arm but i a imagine that is only for people who have wider hips or bottom area then average because it sounds like it would put a lot of stress on the threads in the crank arm,

this is just stuff i have read or watched videos on about measuring a bike to fit someone. it might not be right but that is what i have learned on the net from googling and reading links on here so i am trusting it to be right


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you should try this link:

https://www.biketexas.org/


Last edited by superj; 11-07-2012 at 01:11 AM.
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