I learned that there are three types of brake reaches: short, mediuma, and long reachs. My question is that if long reach brake will fit in any type of fork-and-rim combinations by adjusting brake pad position.. If not, it may be necessary to measure the folk and rim distance of a bike and install brake with right dize reach. What is it?? Your help will be greately appreciated.

Harry

The slots, that the brake pad posts slide up and down in, are only so long. So, on a long-reach caliper, the pads can only go so far up/in, which won't be as far high/close as the short-reach caliper would allow.

Don't get too caught up on the short-, medium-, and, long-reach caliper. Measure what you need and find a caliper whose range will accommodate that measurement.

When I try to buy a used brake (caliper), often bike owners do not have any idea on their brake reach. I was wondering if there is a common size brake reach or most brake will be fit in any bike (road bike in my case)..

Road bike? Long reach ones would probably not reach rims - too long. Short and medium should be OK.

For sidepull Caliber road brakes measure from the center of the mounting bolt to the center of your rim brake surface in millimeters.
Be concerned ...it will not have short, medium, or long marked on the brakes, but will have the range in mm in the brake specs.
Short 39-49mm
Medium 47-57mm
Long 55-73
BMX Long 65-89mm
Beach Cruiser sidepull 79-99mm
Long brakes will not fit in any fork wheel combination. Where do you get this info?
Final word: MEASURE

If you get brakes with too long a reach, you could always replace the wheels with smaller ones. For example, lets say you currently have ISO622 wheels, and the brake pads end up having a travel range of 12 to 26mm (center of travel is 19mm down) below your current braking surface; you could build up a set of ISO5990 (aka 650a), ISO584 (aka 650b) or even ISO571 (aka 650c) wheels. That way you could use the brakes you acquired on your bike, with the simple change of the wheels.

If you are buying used brakes from someone who has no clue, ask if you can get good pictures. Then take a good long look at examples of long, medium, and short brakes on google image or whatever site you like. You should be able to get a rough idea what reach the brakes are by comparing them to known examples. From looking at bike stuff constantly, I can usually identify a bike's frame size within a cm just by looking at a picture.

Edit: To determine what reach brakes your bike requires you will need to measure as others have instructed. You can then approximate the reach of the used brake you are looking to buy by comparing it to known examples. If you don't want to risk buying the wrong brake, buy a new set with the reach your bike requires.

There is a wide range of possible values depending on how the frame was designed: what size wheels it was intended to use, whether or not fender clearance is provided, and so on. Jiveturkey's advice to measure your frame and buy what you need based on that measurement is the most sensible thing to do.

This information is misleading at best. First, there are no caliper brakes with a reach range of 12 to 26 mm, the shortest have a range of 37 to 47 mm. Second, why would anyone pay for a set of new wheels and tires just to match a cheap set of brakes?

I stated RANGE not REACH.

Please re-read: .... brake pads end up having a travel range of 12 to 26mm .... below your current braking surface ....


Ah, a straight man..... ROFL

Brake calipers come in various styles and sizes. Some may not be able to attach to your frame or fork.

If its side pull brakes you have. If they've got a number on them, either on the front, or back. These can be, for instance.
500, 605, 730, 810, 890, 1000, 1080.

These signify the reach of the brake, measured from the brake spindle that fits to the frame or fork, to the centre of the brake pad fitting nut. But you take off the ZERO at the end of the number, to get the reach, in Millimetres. Obviously there is some adjustment at the brake pad slot. Shorter, lower number brakes are for road bikes, that have less clearance between wheel and frame. Longer, higher number brakes are for bikes that have lots of clearance between wheels and frame.

The original poster should give more details about his bike. As its easier to answer questions if theres more information.

True, I did misinterpret your original measurement values but it still seemed an ill-advised "fix" and perhaps the OP wouldn't get the joke.
Just keeping the comedians well stocked with material. You did mean it is jest, didn't you?

If the frame has wheels sized for what it was designed, short reach is probably fine (and longer reach is probably not). Medium and long reach would only be needed/useful if you are substituting wheels smaller than the originals. If you are substituting 700c where 27" was original, the current brakes might still work (but might not). If you are going any further (650-x, etc), you'll need longer reaches.

i don't think this is a safe assumption
without knowing more about the bike

for instance
most 10 speeds came with 27 X 1-1/4" tires
and required at least medium reach brakes

+1 My bought-used '83 Trek 400 came with 27" wheels and "long reach" (47-57) Shimano 105 dp brakes (the original Dia Compes had been replaced by the first owner). The Shimanos had no problems adjusting to match 700c wheels.

Yes.

And seriously; I like fenders on my bikes; and trying to put fenders on my Miyata 310 resulted in going to ISO590 wheels with Tektro R559 (55-73mm reach) brakes. Originally it was equipped with 28-630 tires, with less than 3mm clearance at the brake bridge and FD bracket. I got it as a frame only, was planning on ISO622 rims and 28-622 tires, but that did not provide enough clearance to mount the fenders.

On a Trek 950; I put a 622 road bike fork with a ISO559 rim, the Tektro R559 had enough reach to work in that application too. The original brakes on that fork must have been the 37-47mm reach size you mentioned above.