It is also important to note that your seat needs to be in the correct position to properly determine your reach above. This is a simple and quick way to ensure a powerful and efficient seat height position.
Sitting on your bike, rest your heal on your pedal when it is in the lowest 6 O'clock position. You need to check two things now and you will need another person to assist with this. Check that your leg is fully and comfortably extended. At the same time, when viewed from behind, your hips should be level. If required, adjust the seat height to achieve the ideal balance of full leg extension and level hip placement.
When this is resolved, returning you foot the usual cleated cycling position should achieve the correct amount of knee bend. The position of the bars relative to the seat. This is the bike fit positioning that can cause a lot of trouble and one that we recommend determining over time and with the assistance of a professional bike fitter. If you are new to cycling with average fitness and flexibility, err on the side of positioning your bars at the top of the steerer with one spacer above the stem.
This will allow options to lower the bars over time as your fitness, flexibility and riding continue to evolve. Does this position influence which size bike to purchase?
That should be a secondary consideration after first determining which frame geometry is appropriate for you. If your flexibility is limited or not what it used to be , you may be best to consider a frame with endurance geometry to ensure a higher front end and a more relaxed position on the bike. The following chart provides a rule of thumb approach to determine your bike size based on your height. If you already own a road bike and are happy with the fit. It is good to know you bike fit basics by measuring your seat height, reach, and bar drop.
Seat Height - Your seat height is the distance from the centre of the bottom bracket to top of the saddle when running the tape parallel to the seat post. See the purple line in the diagram above. Bar Reach - The distance from the front tip of saddle to centre of the bars where the stem cap contacts with the stem.
Keep the tape running parallel to ground. Mountain Bike Frames. Shop All. Road Sale Road Bikes. Endurance Road Bikes. Racing Road Bikes. Gravel Bikes. Hybrid Bikes. Folding Bikes. Electric Hybrid Bikes. Electric Road Bikes. Road Bike Frames. Bikes by Gender Mens Bikes. Womens Bikes. Kids Bikes. Bikes by Brand Specialized. Santa Cruz.
Electric Leisure Bikes. Electric Scooters. Brands Specialized. Base Layers. Bib Shorts. Casual Wear. Youth Clothing. Footwear Flat Shoes. Clip-In Shoes. Winter Shoes. Helmets Trail Helmets. Full Face Helmets. Road Bike Helmets. Commute Helmets.
Kids Helmets. Body Protection Knee Pads. Elbow Pads. Body Protection. Neck Brace. Brands FOX Racing. Troy Lee Designs. Drivetrain Bottom Brackets. Jockey Wheels. This is the more crucial number for working out if the bike will fit you. Then take a long straight rule and a spirit level.
Ensuring the rule is level, measure from the centre of the head tube, where the fork passes through it, back towards the middle of the seatpost. This is the effective top tube length. This is simply the length of the front part of the frame that the fork fits through. Although this increases or decreases with frame size, its other function is to dictate the 'personality' of the bike. Even if it is otherwise similar in size, a bike with a shorter head tube will be more aggressive, forcing the rider into a lower, head-down position and requiring more flexibility in their back and shoulders.
Generally, endurance bikes have longer head tubes for a more upright rider position, while race bikes have shorter ones for a lower and more aerodynamic profile. It's another example of how just because two numbers on a chart are the same, their effect on the final position of the rider may not always be identical. Basically, the geometry of a bicycle frame is made up of a lot of numbers, some real and some virtual.
Adding to the difficulty is the fact that frames are both designed and measured differently. Take a standard frame with a normal seatpost collar that protrudes an inch or so above the top tube. How would you describe the length of its seat tube versus a bike with a flush integrated seat post clamp? The position of the saddle will end up in the same place, but the tubes of the frame will be drastically different in length. Some companies also choose to measure frames in willfully obscure ways, for instance measuring from the back of the headtube rather than the centre.
Let us present a simpler solution. Stack and reach simplifies frame geometry down to just two measurements that focus on what matters most in bike fit. Describing the position of the front end, stack is the vertical height between the bottom bracket centre and the top centre of the head tube.
Reach is the horizontal distance between the same points. Their benefit is twofold: firstly, they allow a bike fitter to accurately match your measurements to an ideal bike setup irrespective of any stated frame size.
Secondly, they allow precise comparison between bikes. The Tarmac has a given stack of mm and a reach of mm. That means assuming equivalent bars and stems the Tarmac has the more aggressive riding position, which may sway your choice of bike depending on your riding preferences. The main failing of stack and reach is that it only describes what is happening in front of the bottom bracket.
That said, unless your bike has a particularly unusual design, stack and reach make it pretty easy to compare the essential qualities of any two bikes.
Now adopted by most makers, the stack and reach values will normally be listed alongside the values in the geometry table. A second pair of hands will also help. You want it to fall directly against the centre of the bottom bracket.
Once you hit the spot, the distance shown on the rule between the headtube and position of the plumb line will be the reach.
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