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Discussion Starter · #1 ·
So tell me..... if you have decided not to go custom...what can a proper bike fitting tell you ? What kind of feedback are you going to get and what can you do with it in terms of frame decision ? I'm not talking about stem lengths, seat positions, crank lengths etc - I'm talking about the decision on the actual frame....
Thanks !
 

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well...

You might be able to tell if a particular brands fits you or not. That's important.

Why would you think that a fitting tells you anything else about the frame?

FWIW, there are not such huge difference between brands that any one of them can't be made to fit. If you've got a really long or short torso however, there are some brands that will work better than others.
 

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PTV said:
So tell me..... if you have decided not to go custom...what can a proper bike fitting tell you ? What kind of feedback are you going to get and what can you do with it in terms of frame decision ? I'm not talking about stem lengths, seat positions, crank lengths etc - I'm talking about the decision on the actual frame....
Thanks !
C-40 summed it up nicely.

Depending on where you are in your cycling career and how good the fitter is, a fitter can provide some guidance about a given bike's fitness for your desired purpose, with a bit more finesse than a shop-floor salesman can provide. There are a lot of subtleties in the space between a crit bike and a fully loaded tourer beyond the more obvious choices. Any twit can tell you a bike has rack mounts, but not everyone can adequately describe how longer chainstays might (or not) work to your advantage for your size/shape/positioning.

Lastly, any person can usually fit on more than one frame in a given model, and it's simplistic to say that one is necessarily 'right.' A fitter can help you decide if you want the smaller bike with the longer stem, or the larger one with the shorter, for example. On their own, people tend to make that decision for a lot of ill-considered reasons, like what's on the sales floor or which is lighter by a handful of grams, or which one they believe will be stiffer (and indeed, which end of that decision they really should take once they get the facts right.)
 

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Discussion Starter · #4 ·
Thanks guys...... I get all that and in answer to C-40 I absolutely would not think that a fitting could do any more than you suggest. That's why I am a little confused as to why people stress how important it is - of course I understand if youare going custom it's key - but it shouldn't take hours of fitting and a $150 to work out whether a 57 of a given model or a 58 in a different brand fits better ?
 

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PTV said:
Thanks guys...... I get all that and in answer to C-40 I absolutely would not think that a fitting could do any more than you suggest. That's why I am a little confused as to why people stress how important it is - of course I understand if youare going custom it's key - but it shouldn't take hours of fitting and a $150 to work out whether a 57 of a given model or a 58 in a different brand fits better ?
Ahh. You seem to be confusing fitting with sizing. Figuring out the right size frame is sizing, and it's only the first, most basic step to a good fitting.

Fitting is about not only getting the right bike, but getting it set up correctly for you - all that seat height, setback, stem, spacer, saddle height, tilt, cleat angle and placement, bar extension and drop, weight distribution on the wheels and in the contact points (that's two separate discussions) and so on. You seem to dismiss that as unimportant - but it doesn't take buying too many of the wrong things or messing around not enjoying your rides because you aren't as comfortable as you ought to be to make $150 a solid bargain.

And if you mean to get serious about this as a sport, it's cheap speed. Yeah, really.
 

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Discussion Starter · #6 ·
Who said I wasn't already serious about this spor

You missunderstand me....I'm not dismissing those things as unimportant at all - I entirely understand that they are very important - however, the point I was trying to get validated was that those important "fitting" concerns are independent of sizing and therefore frame choice. Obviously some frames may make these things easier or work better but basically it's very quick to work out what size frame you need - it's the other bits that take the time.
Basically - If I know I'm a 58cm size I can order my frame (which has similar geometry to a frame that I have ridden comfortably) fairly confidently - and I don't need an LBS to fit me in order to order a frame - the LBS comes in when I want to tweak everything else. I'm not confusing sizing and fitting, that is what I was trying to make sure of - and you just cleared it up - and I'm certainly not dismissing the "fitting" process as unimportant - it's very important - it just has very little to do with the frame.
 

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PTV said:
Who said I wasn't already serious about this spor

You missunderstand me....I'm not dismissing those things as unimportant at all - I entirely understand that they are very important - however, the point I was trying to get validated was that those important "fitting" concerns are independent of sizing and therefore frame choice. Obviously some frames may make these things easier or work better but basically it's very quick to work out what size frame you need - it's the other bits that take the time.
Basically - If I know I'm a 58cm size I can order my frame (which has similar geometry to a frame that I have ridden comfortably) fairly confidently - and I don't need an LBS to fit me in order to order a frame - the LBS comes in when I want to tweak everything else. I'm not confusing sizing and fitting, that is what I was trying to make sure of - and you just cleared it up - and I'm certainly not dismissing the "fitting" process as unimportant - it's very important - it just has very little to do with the frame.
A good fitter will fit you on a frame relevant to your cycling experience - basically how you ride and how you want to ride. Sometimes more than one frame size will suit a rider shape - then the rider experience will determine the frame selected. Simply assuming you are a particular frame size can ultimately make a fitters job more difficult even if geometries/comforts are similar - what if you want to go faster on your new steed? A good fitter can advise you as part of the selection process as he will have a broader knowledge of brand and model suitability for your needs.
 

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the problem...

You can take one frame size and usually make the next size smaller or larger fit the same with different stem length and angles, but only one of them will have the best setup. The others will require an overly short or long stem, a lot of spacer under the stem or a high rise stem.

Frames sizes also don't translate between brands. A 58cm in one brand might have the same dimensions as a 55cm in another brand.

To define a frame you have to look at the head tube length, with the headset, the TT length and the seat tube angle. The head tube length (with the headset) is the best indicator of vertical size. Some brands have different models that have the same size number, but one will have a 30mm taller head tube.

If I were to get fitted today, most fitters would raise my bars by 4-6cm, and put me on a larger frame so I'd need a 10-20mm shorter stem. As it is, I use a normal 110mm stem with an 10-12cm drop from the saddle to the bars. The fitter has no way of knowing that I can tolerate a large drop, so he would be conservative and have me setup like a Fred.
 

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danl1 said:
Fitting is about not only getting the right bike, but getting it set up correctly for you - all that seat height, setback, stem, spacer, saddle height, tilt, cleat angle and placement, bar extension and drop, weight distribution on the wheels and in the contact points (that's two separate discussions) and so on.
How do you have any control over weight distribution on a stock bike without compromising seat/bb/pedal fit?
 

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PTV said:
So tell me..... if you have decided not to go custom...what can a proper bike fitting tell you ? What kind of feedback are you going to get and what can you do with it in terms of frame decision ? I'm not talking about stem lengths, seat positions, crank lengths etc - I'm talking about the decision on the actual frame....
Thanks !
To some degree, you should look at how you end up fitting the bike. A frame designer even for a stock bike is going to target a neutral position. That means the saddle rails will be centered in the seatpost and the stem will be an appropriate size for the bike. Usually larger as the frame size goes larger. For a 58, I would expect 110 to be a neutral stem length and that's probably what you're going to find on it on the shop sales floor. The frame is going to be designed for the components it is likely to ship with. So if it comes with 25mm setback seatpost, that's probably what was designed to be best as far as center of gravity.

If you can fit on a stock bike with the saddle close to centered when set to your seat height and only need a 1cm up or down stem change, then you are in the sweet spot of the design.

If you're have to do weird stuff like slide the seat all the way back and then put on a 90mm stem (assuming your 58cm size) then you are probably not fitting the bike well even if your position seems to be good. The reality is your C/G would be too far behind optimum with that setup. A poor result of this could evidence itself as the front wheel lifting while climbing in the saddle or a lot of rear flats since too much weight is on the back wheel.

Basically if the sales guy is having to do anything "extreme" to make you fit the bike, you should be looking for another size or model.
 

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PTV said:
Who said I wasn't already serious about this spor
Easy - No one at all said any such thing. But the thrust of your posts suggest (to me) an underappreciation of the finer details of both sizing and fit, and their interaction with one another. Sorry if I've misunderstood your position.

You can certainly pick a frame based on what you've previously ridden comfortably, and get 'tweaked' into a fit you'll likely find quite acceptable. The question that I'd urge you to ask yourself is how confident are you that the frame chosen is optimal, instead of merely adequate to your physiology and goals? As mentioned before, people can usually be fit to more than one size, but that doesn't mean the choices are equally good. Even where two bikes can be build into identical 'fits', size still matters. It's in understanding and appreciating those nuances that a fitting can be helpful in frame selection.

Let me try it this way. You write " I know I'm a size 58"... You don't know that, though you may believe that you do. There is no such single answer, and I hope to convey an appreciation of that fact.

You and I are apparently roughly the same size. Most nominal fitting measurements put me on a 58ish bike. My main ride is a 57, my secondary a 63* - and they both fit perfectly. Differently, but each perfect for the use I have intended for them. I can also set them up so that they fit identically, but then the adapted bike is not as good at it's intended purpose, nor as good as the one that it is attempting to mimic at that purpose.

You can gain an appreciation for that triangulation through a lot of personal (end expensive) trial-and-error, or by consulting a trustworthy professional.

I've been fortunate enough to spend time with two of the nation's top fitters. I won't name them because I don't want to seem to speak for them. While they both deal heavily in custom - one's entire business is bespoke bikebuilding and fitting services, the other is a stocking and custom dealer with a nationwide reputation as teacher of fitting - both readily recognize that the great majority of people can be perfectly happy with a stock frame. At the same time, they offer that a large percentage of stock frame riders are riding a badly chosen frame for their particular goals and abilities.

To be sure, it's a too-small percentage of people that hold themselves out as fitters that are competant in the sort of fitting I've described. If you don't have that sort of resource available, the approach you propose should serve you as well as any.


* While it's true that my bikes are nominally sized as 57 and 63, the truth is they're both somewhat oddballs. The 57 is a borderline 56 based on TT and HT lenghts, and the 63 would be a 60 in many catalogs, notwithstanding it's standover height (largely a result of an elevated BB). You likely have that sort of nuance under control, but it's another place that fitting discussions can be helpful.
 

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C-40 said:
If I were to get fitted today, most fitters would raise my bars by 4-6cm, and put me on a larger frame so I'd need a 10-20mm shorter stem. As it is, I use a normal 110mm stem with an 10-12cm drop from the saddle to the bars. The fitter has no way of knowing that I can tolerate a large drop, so he would be conservative and have me setup like a Fred.
That's a good point that points out a few interesting nuances to fitting. First, a good fitter would understand that you can tolerate that much drop, though many wouldn't.

Second, drop as a number is kind of fuzzy, and so about as meaningless as 'size' numbers. Someone who prefers to ride 'traditionally' - that is, spending much of their time in the drops - will set to a different amount of drop than someone who sets up their bike for optimum fit on the hoods, with drops meant for relatively brief efforts. I'm not suggesting one is better than the other. Both are legitimate choices that have pros and cons based on how and where one rides.

Third, there's a legitimate question (I don't mean in your particular case) of whether a particular amount of drop should be tolerated. Recent efforts have put everything into minimizing aerodynamic drag, and low-and-flat is commonly a part of that. But that can compromise both comfort and ergonomic efficiency, to what ends up being a less-than result in many cases.

Fourth, it's a reminder that while fit is often about adapting the bike to the human, there's an amount that's about adapting parts to bike. A preference for a particular style of bar will change 'proper' stem lengths and angles, for example.

To be clear, I'm not advocating a raising of bars in any wholesale sense. That does seem to be a current industry trend, mostly because that pendulum has recently been swinging too far the other direction. There's a wide segment of riders that somehow try to equate drop with some measure of adequacy or machismo. (again, not saying you.) I enjoy reminding them that Merckx' drop typically ranged from 3-5 cm's, though he was famous for fiddling with it. Of course that doesn't mean anything to anyone else's fit, but it can be useful to shaking up some commonly held misunderstandings that more is automatically better.
 

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danl1 said:
To be clear, I'm not advocating a raising of bars in any wholesale sense. That does seem to be a current industry trend, mostly because that pendulum has recently been swinging too far the other direction. There's a wide segment of riders that somehow try to equate drop with some measure of adequacy or machismo. (again, not saying you.) I enjoy reminding them that Merckx' drop typically ranged from 3-5 cm's, though he was famous for fiddling with it. Of course that doesn't mean anything to anyone else's fit, but it can be useful to shaking up some commonly held misunderstandings that more is automatically better.
Pretty much agree with everything you said. As a cyclist for over 30 years, I can say that if you avoid extremes such as the current fad of super big drops, you will generally end up with a bike that you will enjoy for a long time rather than something you want to flip in 12 months.

The reality is that the classic Merckx fit is great for pretty much any rec rider and most racers. Trying to fit everyone to look like the lowest guy in the Euro peloton is a great disservice to all but very experienced racers.
 
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