I just recently went through a Specialized BG Pro-Fit (was about $200), and have to say that I'm super happy with the results and experience. The fitter was telling me about some others out there that cost a lot more and take 4+ hours and are more technical, or use more hardware, ie: lasers, though, I could not find them online with some simple searches.

Does anyone have any good experiences with others, or know of any others, and If you've done the Specialized BG Fit, did you like your results?

Edit: The BG Fit site goes in more detail

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    should this be community-wiki?
    – fady
    Commented Apr 26, 2011 at 18:43
  • not certain if this should be CW or not. A CW question of bike fitting systems, with one method or system per answer, would be nice, but wouldn't fit with the existing answers. What question do you want to ask, aside from "tell me about other bike-fit systems"? As it is now, it's a pretty chatty question, and polling the community, but you got a good summary of some of the fit systems from @zenbike. I'm not well versed in bike fit systems; are there enough of them that we need an open-ended CW for this? Or can someone write an answer that summarizes all of them? Commented May 6, 2011 at 17:33
  • @neil: yeah, i think it should be, as Im looking for many answers/ opinions, but that is just my opinion.
    – fady
    Commented May 10, 2011 at 16:37
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    I'm voting to close this question as off-topic because it's just an opinion poll. Commented Sep 5, 2018 at 13:48
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    @DavidRicherby My philosophy is to leave old questions alone. I'm more concerned with the years-late answers that add no useful info or ask a slightly different question. Commented Sep 5, 2018 at 15:11

3 Answers 3


There are several good systems. I'm a certified BG fitter, as well as certified with the retul system. You're familiar with the BG system, as you've already been through it.

Retul is a system which uses power measurement and body position sensors on a 3 dimensional wire frame (virtual) reproduction of your bike and body. It allows an experienced fit specialist to see the skeletal body position without the intervening tissue interfering with the process. The power measurement is individualized to each foot, which means that efficiency can be improved and equalized, and you can see in real time how a body position change affects your efficiency on the bike.

In my opinion, they are both good fits, performed by a skilled bike fitter. A skilled fitter can be defined 3 ways:

  1. First, your fitter should ride a bike. Now, experienced fitters are often the older guys in a shop, so they may not be fast or aggressive riders. They may even be fat. But they still need to ride, to be able to feel the way new bike styles and fit ideas affect the way a fit should be done.

  2. The fitter needs to be experienced at bike fit. Preferably, years of experience. Learning to properly fit a bike is a time intensive process. It is best accomplished by an apprenticeship with an older, experienced fitter, in combination with classroom education on new tools and techniques. It is ok to be fit by someone who is learning, but it will take more time and you should expect more trial and error in the process.

  3. The fitter needs to be willing and able to examine the method of fit he is using and modify it to fit the needs of the rider. Meaning, a skilled and experienced time trialist needs a very different body position than a first time roadie looking to do a century in 6 months. A fit must take into account the fitness, experience, and intent of the rider. A fitter who fits everyone the same way is unlikely to do well for all of his or her clients.

So, to get back to the original question, there are many good fit systems, but what works best for you will depend on your intent, experience riding, and your fitness.

The BG fit is a great option for riders who are more interested in comfort than in efficiency. There is a balance point where comfort and efficiency meet up. That is what a well performed BG fit will find. But, there is a point where a racer, who is generally more interested in efficiency and power than in comfort.

There is a certain amount of pain and suffering that is expected of a rider who is looking to maximize performance, which will come at the price of a loss of comfort. The Retul fit does a great job of maximizing performance, bu the "comfort" zone it looks for is peak performance without actual damage to the body.

Both fit styles in the hands of an experienced fitter can be tuned to the rider. I find that quite often, though, there is bit of "I drank the Kool-Aid" mentality with fitters who have the classroom training, but not the flexibility or possibly the experience to recognize that every fit must be individualized to the rider.

So, I guess, what I'm saying is it is worth checking out other styles of fit, but it should be a style and a fitter which fit with your intent on the bike.

Make sense?

  • how many fit systems exist? I really have no idea if there are, say, two or two hundred. Commented May 6, 2011 at 17:46
  • @neil: i think they're only a few from what i've heard.
    – fady
    Commented May 10, 2011 at 16:35
  • As far as "systems", there are probably 30 organized systems. The FitKit was the first I became aware of in the late 80's. Serotta had an organized fit school combined with an adjustable stationary bicycle which allowed you to match the size and geometry of any bicycle to try it out. It is really the fitter, more than the system, which matters.
    – zenbike
    Commented Jun 16, 2011 at 13:49
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    The BG system link is now broken.
    – andy256
    Commented Jun 8, 2015 at 10:49
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    Fixed. For future reference, best to just edit the link, rather than commenting on it.
    – zenbike
    Commented Jun 8, 2015 at 16:40

If there's one thing I've learned about bike fit over the years, it's that it's rather controversial. I was strictly "old school" since I started cycling seriously in the mid 70s. Standard measurements for seat height, saddle fore-and-aft adjustment, knee-over-pedal adjustment, reach, etc. No high-tech goodies.
You used these "ball-park" measurements to get close and then let your body do the talking....

Much more sophisticated now, of course, but one has to wonder about the degree to which all the techie bells-and-whistles are just to justify the price.
Bottom line is simple.... If you're happy with the results, and you can ride efficiently without pain... You're golden. Every day I see cyclists who appear massively uncomfortable on their rides.

  • thanks m. werner. also, the specialized bg fit is more medical than technical, but when the fitter told me about some high-tech ones that cost more, or are more in depth, i was curious if anyone else has done any of them. again, thanks for your answer.
    – fady
    Commented Apr 26, 2011 at 18:42

Peter White Cycles probably has the best post on the internet about fitting a bicycle:

How to Fit a Bicycle


Bicycle fitting is a subject most people find quite mysterious. Fitting systems with charts and graphs, computer software, measuring devices and "rules of thumb" make for a lot of confusion. But I believe it's really quite simple. Bicycle fit involves compromises. Compromises between comfort and performance, quick acceleration and handling stability, top speed and "taking in the scenery".

Your body's position on the bike affects how you ride. It affects how much power you can efficiently deliver to the pedals. It affects how comfortable you are on the bike. A position that is more comfortable may not allow you to put as much energy into moving the bike forward as a less comfortable position might. How do you decide where to position your body on the bike?

Ask yourself, "What do I want to do with my bike?", "Why am I riding?". A track sprinter is not the least bit concerned with how comfortable he is sitting on the bike. During the race, (which may last for less than a minute), he may only be seated for 5 or 10 seconds. A long distance tourist traveling coast to coast across the USA might spend 5 to 12 hours a day in the saddle, day after day. He is probably far more concerned with being comfortable and enjoying the scenery than with going as fast as he can.

This article relates only to traditional road and cross country mountain bicycles. I know next to nothing about recumbent bicycles and have absolutely no advice to offer regarding recumbent fitting. Nor have I any experience using "aero bars", which allow the rider to rest his forearms on the handlebars.


It's worth reading for this bit alone:

What about knee over the pedal axle?

Most fitting "systems" specify that some part of your knee be directly over the pedal axle at some alignment of the crank, usually with the pedal forward and the crank horizontal. This is pure nonsense. [bolding mine] Imagine two riders, almost identical, but one rider's knees are 1 inch lower than the other's. In other words, the thigh bones of one rider are 1 inch longer than the other, and his lower legs are 1 inch shorter. Everything else about these two riders is identical, including overall height, torso length, arm length and weight. If you position the saddle such that the knee is directly over the pedal axle, the rider with the shorter thighs must have his saddle a little under 1 inch further forward of the other rider. It would be exactly 1 inch if his thigh was horizontal at that pedal position, which it isn't likely to be.

But with the saddle positioned forward, the rider with shorter thighs now has more weight that must be supported by his arms, all because of this arbitrary rule about having your knee over the pedal axle. This makes no sense. What matters is your weight distribution fore and aft, and that's determined by the fore-aft position of the saddle relative to the cranks.

How do recumbent riders do "knee over pedal" anyway?

Yeah, they don't. And they ride just fine, without exploding.

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    Commented Oct 1, 2018 at 14:44

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