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Re: Help me understand bike fit numbers [summers_jm]
To determine what bikes work, take your arm pad stack of 662 and arm pad reach of 432, and compare them to charts like THIS, published by most forward thinking triathlon bike producers in some form. Be careful whether the chart lists back of pad or center of pad as you numbers are for the back, so you should add roughly 3-4cm to get a center of pad measurement. So for this chart by Felt, you would use 662 and 472 and find you fit on a 51, 54, 56 and 58. The 51 is out as you are probably close to or over 6 feet tall, and close to both limits on that bike anyway. You are nearly dead center on reach on the 54 but really stacked up close to the limit, which is not pretty on the IA's, so the question is how set are you in this position, how many extra lbs are you carrying, etc? You are in the aesthetic sweet spot of the 56, and that would be my top choice on this bike, certainly when we look at that 795 saddle height, it makes a lot of sense. You only have 1.5cm to go down on the 58, and at your size, maybe after you shed those 20 extra lbs, you would want to drop down 2-4 more cm, so the 58 is out.

And if you fit on a 56 IA, you fit on quite a bit of other 56s, from Cervelo, Trek, QR, etc.


To set up your current bike, read this:

You need only a tape measure in cm, a level and a set of allen wrenches. Additionally, you may want a plumb line, torque wrench and digital level, but these are generally not required. Sometimes your bike may need new parts installed or it might need to be re-cabled or have some other specialized task completed. Below are the measuring conventions I use, and these are fairly standard across the bike industry. There are different ways to measure some of these, and I try to include the simplest solutions.

· Saddle Height – measure from center of the bottom bracket to the top of the middle of the seat. (For Adamo and other non traditional saddles we measure to the top of the front 1/3 of the seat, as that is the usable portion of the Adamo, while the entire top of the seat is the usable portion for most others)

· Setback – Method 1, With the back wheel up against a wall, bike on level ground, measure the level, straight line distance from the wall to the center of the bottom bracket (A) and again from the wall to tip of the saddle (B). A – B = Setback

· Setback, Method 2, Drop a plumb line down from the tip of the saddle and measure the horizontal distance behind (or in front of for some triathlon set ups) the center of the bottom bracket.

· Setback, Method 3, Hold a level vertical, with the back edge passing through the center of the bottom bracket and measure the horizontal distance back or forward to the seat. Back is a negative setback and forward is a positive setback.

· Cockpit – measure the straight line from the tip of the saddle to the pivot of the aerobar shifters, if you have them. If no shifters are present, measure to the end of the extensions.

· Drop – Place the level on the and angle it over one of the armrests without the pad installed. Make sure it is level and then measure the distance down to the center top of the armrest. Alternatively, you can measure this similar to setback. Measure up from the floor to the top of the seat, and again from the floor to the center top of the armrest. The difference is the drop (or rise in some cases)


· Saddle to armrests – With the elbow pads removed, measure the straight line distance to middle point on the back of the armrest.

· Armrest Width – measure the center to center distance on the armrest pads. Or outer to outer if you prefer.


· Aerobar width – measure the distance between the aerobars at the ends, but before the shifters. Any canting to the bars should be noted as well.

· Aerobar tilt – The simplest method to set your tilt correctly (if you run any) is to make sure everything else is correct and then measure the distance the tips of the bars are off the floor directly beneath them. No angle measure is required for this.

Be aware that moving one thing on your bike almost always affects something else. For instance, when your seat goes up, it also goes back, affecting your setback. So put the setback close to desired, set the seat height, and depending on how much the height changes, you may need to make a small change to setback.
Same principle applies to the handlebars. Moving them up or down also moves them back and forth slightly, so always double check everything and be prepared to make small adjustments.
Last edited by: FindinFreestyle: Feb 8, 18 16:29

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