Bike fitting

gdb2b

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A question for this site's masters and gurus, a question about the art (black?) and science of fitting a bike to its rider. A recent thread about bar ends/riser bars on a MTB setup, and a question from a ride buddy caused me to begin systematically looking for a site which explains the details of (in terms of the orthopedics, ergonomics, and core fitness & strength) proper and effective fit (adjustment and tuning). Does anyone know of any sites that contain this functionality or forum expertise?

Why do I ask? After a ride, a new(er) ride buddy had asked me for any tips and suggestions that might be of benefit to him as he got started. In the process of trying to organize my thoughts to distill a couple of worthwhile comments, I wrestled with how to succinctly explain the oftentimes inverse relationship between ride fit and comfort, while mindful that the advice must first do no harm. I was stumped. I lukewarmly suggested he contact a bike shop and get a fitting session. The assumption was that they would be able to do/explain that which I was struggling to put into words. I didn’t give him crap advice, but it sure felt like it. Therein is the rub. This isn’t rocket science. If this kind of service doesn’t exist, can we help provide the inertia to get it started?

Anybody know of any sites with this kind of content? Imagine a site where you could either select your bike and it brought up the known geometry and sizing configurations, you selected yours from the dropdown listbox or you manually entered your bikes parameters, and then you provided your physical measurement segment attributes (shoulder to elbow, elbow to wrist, hand size, hip to shoulder, hip to knee, knee to ball of foot, weight, etc.). Ideally it would superimpose the bike’s parameters with that of the synthesized rider, and provide suggested bike adjustment settings (seatpost height, saddle tilt, saddle position (reach), optimal bar height, stem angle, and stack height).

For most of us, these tuning adjustments are mostly trial and error. Very little methodology, and even less science. Once you find the sweet spot you tend to leave it alone. Does something like this exist? If not, all you enterprising software developers out there, here is an idea. Run with it. Google Bike anyone?
 
this is retrobike, whatever 20 year old NOS part is available is far higher up the priority order than how the bike fits!
 
Rather than offer some half-baked theory of my own, allow me to direct you in the the direction of Mr Bontrager himself...

http://sheldonbrown.com/kops.html (EDIT: Oops! My browser somehow skipped the above reply and I've just noticed I've duplicated the same link...:oops: )

...who is basically saying that what applies to a pro roadbike, where the rider is fixed in one position for long periods of time and all the energy is directed to the legs (so bike-fit is crucial), has b*gger all to do with riding a mountain bike where you are moving around, in and out of the saddle, all the time.

I, myself, am tall but have short legs for my height (though my knuckles drag on the ground when I walk!) so I prefer 18" frames with long seat posts and long stems; my cro-mega for instance, has a 160mm stem...

P1040215-1.jpg


...and although I am 51-years-old this bike fits me like a glove and I still don't suffer from back/neck pain :cool:

It's all down to trial and error, and personal preference, TBH; what suits me won't suit someone else.
 
:?

Slightly confusing that. The whole point of Bontragers bike fit theory is actually in and out of the saddle - ie moving around and having the bars and controls where they should be and the saddle under your bum where you expect it to be; this is not specific to road bikes at all.

If you are doing XC type of thing, it's usefull input IMHO. If you are into BMX freeride...then well, you aren't actually using a bike primarily to get from A to B and are more concerned with tossing it around like a salad.
 
I have some bikes setup for a 40 degree back angle and some set up for a 90 degree back angle and some in between. It takes different size bikes and stems to make those things happen. Bikes are often sized by seat tube length and different companies measure them differently.

Better to find the top tube length + stem length that gives you the back angle you like.
 
The whole issue of bike fit is snake oil for 90% of cyclists.

Modern bikes are designed with huge tolerance for differing fit.

The art is to tweak rather than radically alter.

A large extent of fit is dependent on what and how you ride. To make a real assessment it follows that observing that would be helpful.

In reality the rider is the one that feeds that back.

You can do a fitting, supply the bike set up accordingly, but the rider might be back with a problem related to the set up because they ride in a certain manner.

By all means follow the advice on fit, but always expect to find your own particular tweak on it once you have some miles in.

The rider's fitness is a huge component, but often underestimated is their level of finesse.

Experience will let a less fit rider get away with a more aggressive set up, but will kill any enjoyment for the fittest novice.

I was minded of this a couple of weeks ago after finishing a build for a friend who has not cycled for many years, though he is very fit.

I set him up a fairly forward biased ride on straight bars, assuming he would be attacking the trails.

As soon as I saw him ride I realised that, even with 130mm front suss, he was crashing into every surface feature.

Back to the car and swapped out for risers, adjusted the stem, and he was delighting in the plushness of the ride.

I have to remember I have always cycled, even through serious injuries, and I just cannot relate to someone who has no concept of moving weight around in response to surface features.

You live and learn.

So they say...
 
I found my favorite pic to trot out when MTB sizing is brought up. They both fit about the same but bars are naturally higher on the green bike. Ideally the green bike would have a zero degree stem and no spacers. 16" with long top tube vs. 18" with a medium top tube. Both setups likely too roadie/XC for most folks' tastes.

 
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