Guru Fitting System

Guru Fitting System

Dorel, the parent company behind Cannondale, Schwinn, GT, Mongoose, Iron Horse and Sugoi purchased the Canadian brand Guru last year. In doing so, Dorel was able to bring into the fold a new fitting system based around what might be the most sophisticated fitting device on the market, the Guru Dynamic Fit Unit. We got a look at the Dynamic Fit Unit at Interbike and had a chance to see the basic process for taking someone through a fit.

GURU software start screen

During the Cannondale team introduction I had a chance to go through a fitting with Colby Marple from Guru. The Guru system offers two different levels of fit, one for production bikes and another should you want to have a custom bike (say a Guru) produced to your personal requirements.

The fitting began with me being scanned by a Kinect unit. Yes, Kinect as in Xbox. As it turns out, Guru’s lead software developer was one of the original developers working on the Kinect unit. The Guru software includes a database of production bikes and their geometry. Based on its scan of me, we were able to choose a couple of different bike models and it quickly showed how neatly I fall between the 56 and 58 sizes.

GURU Rider Scan

The Dynamic Fit Unit (DFU) is the real heart of the system. Quick release clamps allow for easy swapping of both saddles and handlebars and the cranks can be adjusted to provide riders the recommended crank length.

For those familiar with the latest version of the Serotta Size Cycle, one of its big selling points is the ability to use an electric driver to make handlebar and saddle position adjustments while the rider pedals. The ability to move smoothly through a range of possible reaches, bar heights and saddle heights is one of the two biggest advancements in fit methodology of the last 25 years, the other being the rider flexibility assessment. I had one of the original Serotta Size Cycles in my garage for about a year and I’d use it to experiment with my fit. The difference between getting off the bike, making an adjustment and getting back on vs. pedaling continuously while the bar or saddle moves is the difference between the Dewey Decimal System and the Internet. It’s just no comparison.

Where the Guru DFU differs with the Serotta Size Cycle is that servo motors in the DFU unit make precise adjustments based on keyboard inputs by the fit tech, resulting in changes of higher precision and performed at greater speed. But that’s not all. Supposing you like your bar position relative to your saddle height but you want your saddle to go up a centimeter. The DFU fitter can make the two changes simultaneously. Similarly, say you want to try a slightly steeper seat tube angle, the DFU can simultaneously raise your saddle and bring it forward while also dropping the bar and moving it forward in order to preserve the saddle-to-bar relationship.


Wait, that’s not all.

The full-on Ginsu pitch is that the fitter can rock the full position back to simulate climbing on almost any gradient in order to allow you to experience what that position will feel like on Mt. Shootmenow. And if you’re getting a mountain bike fit, you can be swung forward to simulate an ultra-steep descent to get a feel for just how much weight you’ll have on the bike’s front wheel.

My view is that a fit system is just a tool. From the gear to the methodology, a fit system is just a tool to do a job. In the hands of someone with minimal training, it might not be a very effective tool. However, in the hands of someone like Cyclologic’s Paraic McGlynn or Bike Effect’s Steve Carre, the DFU is the most powerful dynamic fitting tool I’ve encountered. This thing could make a great fitter as formidable as Peter Sagan is in a sprint.


My session resulted in a fit that I’d be willing to put my faith in. It differs from my current fit by less than a centimeter in saddle height, while the bar position was more than a centimeter higher with roughly the same reach. I should mention here that because I move between a number of bikes on an ongoing basis and between as many saddles, I’ve grown immune to small differences in ft. I had to learn to put up with changes in my fit from bike to bike, even when I’ve gone to great lengths to replicate my position exactly. Exactly just never happens. Because I’ve managed to ride well on a number of bikes with slightly differing fits, I’ve come to believe that when someone (be it fitter or rider) starts to get fussy about that last millimeter they are failing to understand the inherent adaptability of the body. And I write this with the knowing admission that I’ve suffered problems at the hands of bad fits by alleged fit experts.

I think part of the genius of the DFU is that all the rider has to go on is the feel of the fit. With no stem to look at nor the visual cue of seeing the drop from the saddle to the bar framed by the bike itself, all you can really go on is the feel of sitting in the saddle and reaching for the bar. When the original Serotta Size Cycle was introduced I was skeptical that a good fit could be achieved by a fitter simply listening to feedback from the rider. I was perhaps right to be suspicious of the original iteration, but today it’s an approach that makes terrific sense. It does require that the person being fitted talk a lot about what he or she is experiencing as the key to a good fit is communication, but even a relatively quiet person can get a great fit from a good fitter. The best can see unwanted muscle tension the way poker players can suss out tells.


Finally, I’ll grant that it might be a challenge to place your faith in this approach until you’ve experienced it. I learned to give a lot of feedback as either the bar or saddle is moving: no, no, no, not bad, okay, yes, yes, errmm, nah, no, no, no. It was interesting to me that Colby had the same reaction to my feedback that Steve Carre at Bike Effect did. They both noted that they saw an easing of tension in my shoulders just as I started to say “yes.”

Again, the Guru system is just a tool, and that goes double for the DFU. However, in the hands of a great fitter I think the DFU has the ability to help a fitter arrive at a result that the client will believe in. Why? Well the dirty little secret of fitting is that the single biggest challenge a fitter faces is getting the client to not just adopt the recommendations, but to stick with them long term rather than switching the bike back after a ride or two. The DFU provides an experience that makes the recommendation one’s own, not some outside piece of advice. When I was first trained as a fitter, recommendations were made based on a set of tables the correlated to the rider’s personal dimensions. The process was effectly: here’s what you are, so here’s what your fit should be.


The DFU, more than any other fitting tool I’ve encountered, upends that convention by making the fitting a matter of self-selected comfort. That might seem obvious to the point of naive, but really a proper fit is fundamentally a function of comfort and who can better know your comfort than you?

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  1. jorgensen

    It looks interesting, thanks for the report.
    It brought to mind a notion I saw practiced where I worked long ago, when a client came in who had a current position way out of whack but had been riding a decent amount, the client did not leave the shop with his ultimate position, but when practical was incrementally eased into it over time, a week or two between steps. Easy to do with saddle position back then, more difficult to do with reach, from that I became an incrementalist.

  2. MCH

    The question that seems to be answered by this fit is, “what is the most comfortable position for me on the bike?” The questions that doesn’t seem to be answered is, “what is the most bio-mechanically effective position for me on the bike?” It would be interesting to see how these 2 positions are/aren’t the same, and then to explore the compromises made with either position.

    As someone who really likes the data and technology of modern fit systems like Retul, the idea of throwing the bio-mechanical references out the window and going by feel seems really intriguing. I wonder where I’d end up? I’m assuming that the fit tech must be guiding the process within some parameters based on fitness, flexibility, intent, science, etc.? Then, the “feel” part finalizes the process? In any case, I’d like to try it.

  3. Adam

    Definitely looks like a big step forward in fitting as long as the fitter has a solid grasp of what they are doing.
    MCH: It would depend on your definition of ‘biomechanically effective’. At one extreme would be the optimum biomechanical position which would only really be of any benefit to top end pro racers & even then its going to be a bit hit & miss, it’s not always going to be comfortable.
    For almost everyone else ‘comfort’ IS going to be biomechanically efficient for that person. Perhaps not strictly the most biomechanically efficient position based on science but it will be the best compromise.

  4. bigwagon

    As you noted, all these sophisticated new fit systems are ultimately just tools. In the hands of a expert, they can yield great results. But the basic concepts of bike fitting don’t really change just because you can measure more accurately or make on the fly adjustments, and having access to a $10K fit system does not make the average bike shop mechanic an expert fitter. They key is still to find a fitter who can translate what the rider wants/needs into the right position on the bike. That is the harder part.

  5. Gary

    The rider feedback method can work fine for more experienced riders but for novice riders, it may just feel “different”. They have not context to know good from bad.

    There’s certainly been a lot of focus on the DFU’s and fit “systems” in recent years. Specialized bought Retul, Shimano and Trek have a system, Guru is now under the Cannondale banner.

    As is constantly noted though, you can’t do a fit by a set of box calculations. It takes an experienced person operating the gear. That’s really the good news/bad news as the number of fits are sold in retail stores, the number of bad ones likely will rise as well.

  6. soybean

    Just a tool indeed, but it makes the job more fluid. I will say that being able to simulate real world dynamics is deff a nice feature. I don’t have, but have used a Retul bike add it was deff a cool way of applying the Body Geom Fit method. Can the Kinetic system be used just as a sizing tool on for the start/ purchase of a bike?

  7. tv_vt

    Are those your measurements in the Kinect Camera image (with 1933mm height)? If yes, you’re around 6’4″ — and you fall between a 56 and 58 frame? Again, if yes, something’s wrong here… at least in my book.

    1. Author

      MCH: One thing I didn’t mention is how loads can be placed on the bike as you pedal thanks to a Computrainer unit. A thorough fitter will have the ability to find out of that low position someone chooses really is biomechanically efficient. For older guys like me who don’t mind sitting up more because we no longer race, there might be a risk of sitting up more than is necessary, but I can’t think of a way to guard against that.

      Soybean: Yes, the Kinect system can be used to help determine the likely size for a rider; that’s its primary use—as a starting point.

      Gary: That’s why I say it’s just a tool. I’ve encountered fitters who have been able to correlate my perception with a perceptible reduction in muscle tension, something I might have missed on my own. They were able to demonstrate to me just how “on” my perception was.

      TV_vt, James: No, those aren’t my measurements. That’s a screen shot they provided me. I’m rather surprised that you think I know so little about fit that I could be 6’4″ and think I was getting a good recommendation with either a 56 or 58cm frame.

  8. Patrick O'Brien

    Padraig, that was an interesting report. Could this fitting process also be adapted to a loaded touring bike?

    If you would forgive a change of subject, last year we had a discussion on the safety of bicycle helmets. The first sentence of this piece, which mentioned Cannondale, reminded me that they have brought out new helmets with reinforced EPS foam and extended coverage. Bell and specialized have followed suit. Could this be a subject for a future post on RKP?

    1. Author

      Patrick: Yes, absolutely. The Guru fit system is, in my opinion, really only limited by the talent/knowledge of the fitter. If the fitter understands touring bikes and has this, I think it would be a great tool to achieving that fit.

      Regarding Cannondale’s helmets, I’ve done one, the Terramo, already and will likely do more in the future. Here’s a link:

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