How to Fit a Bike

Critical mass cycling event in Lisbon
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The fit of your bike affects every aspect of cycling, including comfort, control, and safety. It also plays an important role in efficiency, or how effectively your leg power is transferred to the bike. Serious cyclists often pay for professional bike fittings done in a bike shop, but for recreational riders, comfort and a few rules of thumb can guide you to a good fit. You must start with a bike size, or frame size, that is a reasonably good fit for your body size. From there, you can easily adjust both the height and position of the seat and handlebars to fine-tune the fit. 

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Stand Over the Frame

For most riders, the first step in getting the right size of the bike is to stand over the frame with both feet flat on the ground. A properly sized road bike frame will have an inch or two clearance between the top tube of the frame and your crotch. Not too much, not too little. A mountain bike should have more space, maybe the width of your hand across your fingers.

Some bikes don't have a high (or horizontal) top tube going between the seat and the handlebars. In this case, check with the bike manufacturer for sizing recommendations. They can tell you the range of frame sizes suitable for your height. 

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Adjust the Bike Seat Height

Set your bicycle seat at a height that allows your leg to extend until it is almost completely straight when you are pedaling while sitting on the seat. There should be only a slight bend to the knee when your foot is on the pedal in the bottom position. This will maximize power and minimize fatigue.

Sometimes people think that you should be able to stand with your feet flat on the ground while your rear is on the seat. This is not the case. If you can touch the ground while sitting on the seat, it should be with tippy-toes only, or with one foot on one side but not the other. If you are able to touch the ground while sitting on the seat it is a sign that either the bike is too small or the seat is too low and you won't be able to fully extend your legs for proper power delivery to the pedals when riding.

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Adjust the Bike Seat Level and Forward Position

For maximum comfort and pedaling efficiency, your seat should be pretty much level. Too much forward tilt, and you'll feel like you're sliding forward. Too much backward angle, and you won't be able to get any power and you'll have the sensation that you're slipping off the back. Both of these situations are distracting and uncomfortable.

When sitting on a bike seat, your weight should be borne by the same spots on your pelvis that you feel you when you sit upright on a hard, firm surface. 

For making the tilt adjustment, most seats have a bolt on the seat itself or on the clamp that holds the seat onto the seat post. This is different from the bolt or clamp that secures the seat post to a frame, the one used to set the seat height. 

In addition to adjusting the tilt angle, you can also move the seat forward and backward in relation to the seat post. Sliding the seat forward shortens the distance between the seat and the handlebars, making the frame feel a bit shorter. Sliding the seat backward has the opposite effect. There's no rule of thumb for this adjustment; just find the position that feels the best. 

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Set the Handlebar Height

The goal of handlebar height adjustment is to find the position where you can ride comfortably without putting a strain on your back, shoulders or wrists. There is a lot of personal preference here, and a fair amount of variation between body types, so don't be afraid to experiment until you find the setting that is best for you. And remember, the staff at your local bike shop are always happy to offer advice on finding the proper fit.

Generally, the following guides may be used for different types of bikes:

  • Road bike: The top of the bike's handlebars should be 1 or 2 lower than the top of the seat. This allows for a forwarding-leaning, aerodynamic riding position.
  • Mountain bike: The handlebars will often be set even lower, perhaps 1 to 4 inches below the saddle. This lowers your center of gravity for better control. e pavement. Also, mountain bike riders often come out of the saddle to negotiate bumps, logs, and other obstacles, and the lower handlebars provide a better, more balanced position in distributing the rider's body weight across both wheels.
  • Hybrids and Cruisers: These bikes have you sitting more upright in contrast to the road and mountain bikes; the handlebars are higher, approximately 1 to 2 (or more) inches higher than the seat. This means much more of your body weight is borne by the seat rather than the handlebars. 

Adjust the handlebar height by moving the stem (the "gooseneck" piece that connects the handlebars to the bike frame) up or down. Consult your owner's manual for the proper procedure. With some handlebars you can also pivot the handlebars forward or backward; this adjustment is made where the handlebars are clamped to the stem. 

All handlebars have a minimum insertion mark. Make sure you don't raise your handlebars into a fixed position so high that you pull this mark up out of the frame. Below this point, it means that there are less than 2 inches of the handlebar stem remaining inside the frame, and the handlebars are susceptible to breaking, which could lead to a serious accident.