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How To Build A NAHBS Bike – Part 2: Ensuring Proper Fit With A Specialized Body Geometry Fitting

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Specialized-Body-Geometry-Fit

Working into the process of building the custom Matter Cycles BeneFat, I wanted to make sure that all of this effort was not wasted, and that the bike fit me well. I owned about 30 different mountain bikes in the last 15 years, and I’ve always been able to dial in a comfortable position. However, even though they were comfortable, I never knew if they were actually right for the flexibility and geometry of my body, since most of my setup was guess-work.

Deciding to use the bike I spent the most time on recently, and was very comfortable on, I went to Erik’s Bike Shop for Certified Master BG Fit Technician Jason Wolf to insure I was on the Ibis Ripley properly. In addition to dialing in the Ibis, it would give me the fit geometry numbers I needed for the BeneFat.

What I found was really interesting. While I was comfortable, there were quite a few changes that could be made to fit the Ibis better, and make sure the custom bike was truly dialed in. Read on to see the results and why every cyclist should get a fit someday…

BG-Fit-Foot-Measurement Specialized-Foot-Fit

The fit started with a wide variety of body measurements, as well as the unique foot and butt measurements specific to the Specialized Body Geometry program to also insure proper saddle and shoe fit. As a part of their Body Geometry program, Specialized offers measuring tools to properly fit a person to their accessories. More than just sizes, Specialized offers saddles in up to 4 widths, shoe insoles in 3 different levels of arch support, Varus and Valgus shoe shims, differing shoe widths, as well as other items.

Specialized-BG-Fit-Butt-Measurement

Usually around $250, a fit is a really good insurance plan to start with before having a custom bike built. It is a good place to check your assumptions, as even though I consider myself an “expert” bicycle mechanic, and I felt comfortable on my bike, another set of eyes trained to look for certain things can help verify your fit at the least, or in my case, find some areas to be corrected to be even better on the bike.

BG-Fit-Outputs

There are a lot of outputs from the fit, as Specialized uses a Compu-Trainer and video capture with markers on body points to analyze your ride pre-fit, and then post-fit. As you work through the fit, the technician has you ride up to around 80% effort for a decent amount of time, and then runs a video capture for a few seconds. Then, from identifying markers placed on joint areas of your body, they can measure how you are on the bike, and compare them to the flexibility measurements taken earlier while off the bike. When its all done, a very detailed PDF document with before and after measurements is provided, which can be used to help your custom builder dial in the perfect bike for you.

RESULTS:

  • Generally, I was too cramped and bent over on the Ibis. The bike was set up with a straight seatpost and 90mm, 0 degree stem, but to get to proper position, I should be on a seatpost with about 25mm of setback, as well as a 110mm stem with 10 degree rise. Those numbers are specific to the Ibis, revealing that I should actually be on an XL sized frame Ripley. This is all relative, as I was comfortable on the Ripley as it was, but this fit revealed areas where it may have been pushing my body beyond what is comfortable.
  • Due to the straight seatpost, my knee was too far forward over the pedal, by about 3cm. I was also running the saddle a bit too low, and the fit resulted in giving me some replicable numbers for future bikes of an 82cm saddle height from BB center to top of seat, and the center of the saddle being 8.4cm behind the BB center. When replicating these two numbers, my knee will always be in the proper position over the pedal, assuming I always use 175mm crank arms.
  • I have a moderate amount of limited flexibility in my hip flexors, so it was measured that I have about a 100 degree angle between my back and femur at the top of the pedal stroke. This was determined by measuring the flexibility of my hips off the bike. Before the fit, this was at about 107 degrees, caused by too much bar drop. The fit helped me find that my proper reach is 56.2cm with about 3.5cm of drop to the handlebars to achieve the 100 degree angle.
  • The largest problem I had was a mis-alignment of the hips while on the bike. When measured from behind, my right hip was almost an inch further back than my left hip. This could have been caused by a few things, but there is no exact science. The proper saddle width helped even them out a little bit, and then some Varus shimming of my left foot to compensate for my knee diving inwards a bit at the top of the pedal stroke. Both of these straightened out my hip a bit, and will help in the future with setting up any bike, since the shimming was in my shoes, and I was changed to a wider saddle.
  • Most of all, I now have a very good set of baseline numbers that will help Collin Schaafsma at Matter bikes create the perfect fit on my BeneFat, but also help me set up future stock mountain bikes properly from the first ride.

www.eriksbikeshop.com

www.specialized.com

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34 Comments
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Pete
Pete
9 years ago

*Ensuring

lazydave
lazydave
9 years ago

Ha! Get back to work Pete 😛

rob cole
rob cole
9 years ago

its money really well spent. I’ve worked for a number of Specialized dealers over the years, as well as 2 “Concept Stores” that had trained Body Geometry fitting staff. Working as a bike mechanic, I’d be asked to regularly built custom bikes for customers that had been through the process.

Of course, I got interested and talked the fitters into doing a couple of fits for me, during some slack time. Results were interesting, and adjustments to my bikes resulted in a more comfortable ride with better efficiency, and adjustments that eliminated ongoing pain on my road bike during long rides.

Whatever customers might think of “Specialized” as a brand, their BG Fit process is very comprehensive and from what I have researched, has 30 years of solid research and date from 1000’s of medical bike fits behind it, from the medical practioners behind the system.

I don’t work for a Specialized retailer at the moment, but BG Fit is something I’d recommend as many of the competing systems I’ve researched, are pretty dubious in terms of their science?

Dockboy
Dockboy
9 years ago

Didn’t Keith Bontrager dispel KOPS, like, 16 years ago? I still don’t understand how your knee is supposed to be in the same position from Track to road to XC to #enduro, but only on level ground.

satisFACTORYrider
satisFACTORYrider
9 years ago

so this fit is for an xc setup on your, ripley?

epicthroatbeard
epicthroatbeard
9 years ago

so now you have a 110 mm stem that you could use as a lever to move a boulder.
Now your bike sounds really well set up for those 80%-effort-on-a-trainer-in-a-shop sort of days.
Computers don’t ride bikes. they sure can’t tel what stem length you need and there is no bike made that handles better with a 110mm stem.

Rico
Rico
9 years ago

Check out Steve Hogg. I think its brst to learn about fit on your own if you are a serious cyclist and use video (ipad) and a power meter to take measurements. I made templates in a video program that show knee tracking and joint angles. I have also had team coach fits and fit studio fits, but its not a static thing and i feel like fitters ALWYAYS lean towards upright comfort positions rather than the ideal balance of power/aero/comfort.

lazydave
lazydave
9 years ago

Keith dispelled the whole knee over pedal thing, however, with no real alternative. But yes, it does change with your top fit based on how aggressive you are set up. Time trial or track bikes are basically being pivoted forward around the bb and will absolutely change the knee over pedal. This is a very good reason why Tim went to a fit pro. It’s his job to decide what makes sense to use for fit and what doesn’t. Since Tim was going with an XC fit using a knee over pedal makes sense.

James S
James S
9 years ago

Where are the actual riding results? Lots of people seem to get really impressed by numbers and measurements, but the proof is in the riding.

Also I agree with epicthroatbeard – if you are running a 110mm stem and setback seatpost, you really need to get a larger frame.

Psi Squared
Psi Squared
9 years ago

Any fit should be considered a starting point, and that includes the KOPS bit, especially as there’s nothing objective supporting the idea of KOPS.

Steve Hoggs ideas on cleat placement might have some merit, but he’s got some other ideas–about wristbands affecting fit and the like–that are just plain whacko.

Roy
Roy
9 years ago

LIke any fit program Hogg included, cookie cutter bike fitting is ball park science at best. But from looking at your before, you were cramped and after you are less cramped. that cant be bad, and you should feel faster and more efficient after getting some time on the new position. from my trailhead eyeballing of riders most are on too small a frame thinking they will be better handling but the opposite is true, just check out Mondraker marketing. Surely extreme but something to add to the future of fit thinking…

satisFACTORYrider
satisFACTORYrider
9 years ago

fit it to your attack position, skillset/riding style. otherwise, good luck finding grip with your tires on the trail with that onyerbutt start point. mondraker stretches the bike not the rider…

AL
AL
9 years ago

i would reiterate James’ question: how did this “fit session” affect your riding experience?

if you don’t feel a real demonstrable improvement on the bike, who gives a carp?

Rivers
Rivers
9 years ago

Shout out to Jason!

Chader
Chader
9 years ago

A straight or set-back seat post is no indication of a proper or poor fit on it’s own. The saddle fore/aft position is important to set based on intended usage of the bike.

That is why this is one of the first adjustment made in the BG Fit process. As noted above, KOPS is a common starting point, but should be adjusted as needed (usually forward to match a lower, more aggressive front position). Saddle position should be optimized for best efficiency in height and fore/aft.

Only after setting the saddle, you can move to the front of the bike and adjust the stem and handlebars to fit the rider and usage.

However, sometimes you have to fit the rider on the bike they bring in even when it may be less than ideal.

I agree, a 110mm stem seems to indicate a short front center (reach) and that the rider should size up on the frame. In this case, it is good to note the issue so the rider can correct it with future bike/frame purchases.

craigsj
craigsj
9 years ago

Garbage in, garbage out.

Would any experienced cyclist ever believe his fit was 3cm (!) off in knee position? Seriously?

KOPS is laughable. There’s a whole range of fits that include identical angles at all joints. Only one in that range is KOPS yet all are equally valid. How does KOPS work for recumbents?

Do not want a fit like this, especially when you have to pay for it.

Pete
Pete
9 years ago

Anyone doubting the BG Fit should look at how many Grand Tour and Classic-winning road teams employ it.

serious
serious
9 years ago

@pete, and that’s exactly what specialized want (deleted) to think. The marketing has obviously fooled you.

Also to those who think there aren’t alternatives to kops, there are. Those based off centre of gravity, but using this technique requires more knowledge than one can get by filling out a form on a cereal box and attending a seminar for a few hours.

Kris
Kris
9 years ago

Not doubting the usefulness in road and XC, but bike fitment certainly changes when your talking about trail riding and your only on your saddle 50% of the time. Handling and weight distribution would carry a much higher value out on the trail compared to riding a century.

CXisfun
CXisfun
9 years ago

@Pete: a bunch of sponsored riders have won on SRAM components, but that doesn’t make it any good. Using the fact that sponsored riders have used it is a really poor indicator of how well it works.

ryan
ryan
9 years ago

So… What was the wattage/kilo increase after the fitting compared to pre-fitting for same exertion level?

Surely this fitting was backed up with science if you were trying to get a good fit.

At the very least, psychologically your fit may feel better.

matt44
matt44
9 years ago

Yay, Erik’s!

COrider
COrider
9 years ago

@Pete
You know why those professional riders used it? They were PAID MONEY.

Just more marketing ploys here. There are no rules to how a bike must fit….its whatever feels best

Chader09
Chader09
9 years ago

@Ryan,
Who said power increases were a goal for this fit?

That may be important to some, but many fits are done to improve comfort or alleviate pain so the rider can ride longer or enjoy current distances more.

Posdnuos
Posdnuos
9 years ago

@CXisfun

How about: Nearly everyone I see on the trail uses SRAM products. Is that also not a good indicator? Or just bunch of sheeple sucking on the marketing teat, forced at gunpoint to buy SRAM products? Apple uses the same tactic, where their marketing prowess literally drags people into Apple Stores against their will to buy products that don’t work.*

*but word on the street is that they mostly do work, and phenomenally at that.

Veganpotter
Veganpotter
9 years ago

As a fitter, I always fit mountain bikes with caution. If you live somewhere flat and you don’t travel, its pretty easy. However, if you live somewhere with very steep climbs, you can easily turn what seems to be a comfy/efficient fit on the trainer into a very dangerous situation on a mountain bike. Its not hard to create a wheelie mobile. Of course, if there are physical limitations with pain, flexibility etc the rider is going to have to accept compromises. If the person is pretty healthy, you’ve gotta take bike handling into account. I’m not just talking stem length/leverage but weight over wheels, length of saddle to allow more front to back movement…these are all things that are much less of a concern for a road fitting since road cyclist are mostly going straight all the time.

Pete, as for the BG fit being spectacular due to teams using it. Those teams are largely on Specialized bikes. Everyone else pretty much gets set up on Retul with Retul Univ. trained fitters. Of course, these are just fitting tools. The fitter needs to know what they’re doing and just like the medical field. There are poorly skilled people that have their license.

JR
JR
9 years ago

Go see the bicycle fit guru in Minnetonka. He is the best in the business. He does not hold himself to one specific protocol.

JR
JR
9 years ago

Chris Balser

lander jennngs
lander jennngs
9 years ago

Well, BG Fit is a tool which is only as good as its user.

Experience, observation, understanding the cyclist… that makes a fitter, nothing else.

YOU CAN NOT UNIVERSALLY APPLY ONE SET OF RULES TO ALL CYCLISTS.

EagerBeaver
EagerBeaver
9 years ago

Wow! I love a good comment section w/ a whole bunch of expert OPINIONS!

@Rico power meters should not be used to determine a proper position, especially on a cyclist w/ a ton of muscle memory in a certain position. They will almost always produce the most power in the position that they are used to. Making a change to a more efficient position, usually takes time to adapt . Compare power numbers a month after the fit to see if the changes made sense, they usually do. Alot of “fitters” move the bar and saddle around a bit, and then just essentially move things back to your old position. The only difference is they rotate the fit forward, meaning slide the saddle forward and up, lower the bars and add 1cm to the stem, and use your wattage to justify this. Its kind of a trick, some less honorable “Fitters” use. Also, handlebar height is really a function of hip flexion, if the bars are to low,and you don’t have the mobility to effortlessly get over the top of the pedal stroke you will start your power phase latter and essentially shorten it. Do the same power test in the drops, and on the hoods if you can’t produce the power in the drops, your probably to low.

KOPS really is just a guideline. Most Fit systems/schools teach a +/- 2cm either forward or backwards, Its more about weight distribution then anything else.

Oh internet.

K11
K11
9 years ago

@EagerBeaver. Obviously you are “sold” on this article & bicycle fitting. Seems like the ones that gravitate toward the whole fit process seem to be the old, inexperienced, OCD types, and last but not least, people with a little extra disposable income, that fit shops pray on.

Just another OPINION! Oh I love the internet.

Psi Squared
Psi Squared
9 years ago

I would think that fit shops would “prey”, but maybe they do “pray” over their customers. If you’e going to insult people, you should at least use the correct homonym so that you don’t look like a fool.

Thesteve4761
Thesteve4761
9 years ago

@vegan- specialized owns retul, so…

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