merziac

Perception, physiology, preference, bad habits, stubbornness, tips and tricks from racers and "experts", et all can make it very hard to get there.

I have walked into many bike shops, guy says "how come you got your seat up so high?", I say "I don't know, how about you tell me?", out comes the plumb bob, sit on the bike, swing the bob, "huh, that's exactly where I would have put it" , I say "huh, whataya know?", apparently not enough.

Way too much to it, calculations only work if they take the unknown factors into full account and how could they if they are unknown?

Age, injuries, maladies, the p's and q's above and a whole lot more, this is where an experienced fitter/framebuilder can be invaluable, they have the knowledge to take much more into consideration and translate it into real life, despite numbers and formulas that don't tell all that you need.

You may need a wizard, these guys come very close IMO.

CroManganMan

I'm 43, probably just under 5’10” these days and last time I wedged a book between my legs to measure my inseam, it was 35”! So yep, I have issues with fit because of my freak long legs. I've never been comfortable in a bike. After shoulder and back pain, I decided for a custom fit. They gave me 58cm ctc seat tube by 52cm top tube! It was a racing fit because I didn't know there were other choices, and it had a threadless stem so I could never get the bars high enough to not be in pain or numb. Plus, I felt like I was riding on casters because I was up so high and the top tube was so short. I gave up after that and started a family so no money or time to try again.

Later I learned I had really bad posture and flexibility from working at a desk all my life (school and career). I'm hoping doing yoga will continue to improve it so I can finally ride a bike without pain. But I have NO idea what size frames to look for. Right now I have an early 80s 23” ctt Puch Pacifica that I paid way too much for considering it has straight gauge tubing. I also found a really abused 23" ctt 1987 Schwinn Tempo that I had to rattle can paint. I feel like they'll be too small based on how much seat post is sticking out, but I don't have anything else and finding something taller, decent and cheap around here is hard. I guess I'll try riding them and see what I'd need in a taller frame. I have a feeling a French 60s or 70s bike would be better with around a 60-61cm seat tube but 57-58 top tube. At least I think older French bikes had shorter top tubes. Gotta have a quill stem to get the bars up high.

I'd appreciate any suggestions others have on what I should look for. 24"? Would a 25" frame be too tall? Sounds like someone else with a 35" inseam rides them. But he is also over 2" taller than me. Thanks

John E

55cm C-T in a "square" frame is my ideal.

With the respective elbow against the nose of the saddle, my left fingertips just touch the top of the handlebar; my right just miss it, due to a Colles' fracture of the radius (not bicycling-related) 25 years ago. Knee Over Pedal Spindle also just about holds for me, as well, as does "knees straight with heels over pedal spindles." My inseam is about 32" and I wear 30" long pants.

merziac

Ask your yogi if they know a bike fitter that they work with, if not seek one out that subscribes to both practices. Most fitting systems have a predetermined outcome which is why you got a racing frame. Seek out framebuilders that have a good understanding of your situation and see if they can help make better sense of it.

mackgoo

I too am 69"'s with a 30" I.S. I've ridden a 55 all my life. 55cm frame, 175mm crank, 130mm stem. That's it and it's worked well for the last almost 50 years.

CroManganMan

Good idea, Merziac! Thank you! I'll search online for someone specializing in fitting freaks like me because I'm my own yogi. Really I use an old book called "Power Yoga" by Beryl Bender Birch. Good book, BTW.

merziac

Send an email to them and reach out in your area. We have Micheal Sylvester who pioneered Trek and Specialized's fit system's and became a yogi when he had injuries that he couldn't resolve from his fitting expertise.

I have never used him as I have always been able to get my fit sorted on my own but he was/is a fan and customer of legendary builder Jim Merz who I as you can tell from my handle am a huge fan of.

I have 5 bikes built by him and the 3 I ride fit and ride very well for the fit that they have for me. One is Jim's he built for himself, one is a full on touring built for a guy that wanted it for Paris Brest Paris and the third is a big one that fits me like a glove and rides like a dream I bought from the original owner.

Jim built any and all kind of bikes but his touring bikes are legendary with very good reason IMO.

Prowler 

Mike, I'll add another aspect of this, for the rare few who have multiple bikes. Repeating the fit. I spent a lot of time getting the fit right on my Raleigh Pro. It's all day, long miles, variable terrain comfortable. I then used that as a model to get the fit (ergonomics) on each subsequent bike the same. I standardized on brake hood placement for the drop bar bikes. I then use a fixed distance from the pedal spindle to the sit bone spot on the saddle - saddle height. Having the hoods in the same place on each bar, I can then set reach the same. For me "reach" is the distance from the sit bone spot to a line across the back of the hoods. I dial that in primarily using stem length, a wee bit using saddle position, though that is only for fine tuning. Knee over the spindle is primary for seat position. Stem height varies according to my mood, less critical for me. Height is somewhere between level with the saddle to 1 1/2" lower.

These three 'touch points' maintain the basic fit on my frames - 8 road bikes with frame sizes ranging from 55 to 60cm c-c. I use these three dimensions for my two mtn bikes too but the stem length is, of course, done differently.

All of this fiddle-faddle is captured on a wooden rod that furniture makers call a 'story stick'. Easy to check these fits when needed. I keep the contact triangle - my feet, sit bones and wrists - the same and vary the bikes under me. Works well for me.

Lascauxcaveman 

Let's see: I am 71" tall and my perfect fit is a 61cm bike, give or take, with reasonable length seat post and stem. So the formula is: take the number of inches you are tall, subtract ten, and make those inches into centimeters and that is your perfect bike size, in Cm. This is an ironclad formula for everyone; a perfect and infallible rule that you won't argue with unless you are an idiot.

Huh? Whadaya mean "61cm top tube or seat tube?" How the hell would I know? What do I look like, a bike shop fitter?

canklecat

Seeing a friend along a rural route the other day reminded me of his uncommon bike fit and riding style. I think he's around 5'9", maybe 140 lbs, but he looks like he should be taller. His torso looks like a guy 5'11" to 6', but his legs are just a little short in proportion. Looks like his bike frame size is 56cm and he prefers a stock longish stem, around 120mm. But instead of lowering the saddle a bit to suit his proportions for a "typical" fit, he prefers the Jacques Anquetil toe-down pedaling style.

Sure works for him. He looks like he's just spinning around 90 rpm, not much effort, but he's unnaturally fast. I saw him loafing along in my rear view mirror the other day and it was spooky how quickly and easily he closed that gap, from around 1,000 yards to 400 yards to 100 then suddenly on my tail. Never even looked like he was trying hard. He hardly ever uses the drops either, mostly rides the hoods and sits pretty upright. And he holds many local KOMs and is in the top ten on every segment worth riding. Pretty incredible for a guy in his 50s, and as far as I know he's never raced (although he does Zwift now). Just a natural time trialist.

I tried his toe-down style for awhile last year, raising the seat post, etc. Felt like it was gonna wreck my knees and hips.

Don't try to copy someone else's bike fit.

Road Fan

I REALLY like the look of the black Torpado, it seems to have a lot of BB drop!

I start with my PBH measurement and the equations, then ride, first to see if the saddle height, setback and tilt work. Usually not, so I lower thsaddle until I get close to "straight leg with heel on the pedal, and I check that with a set of flat pedals with no toeclips installed. Usually then I only need to work on setback, tilt, and sometimes rotation.

After the butt-to-pedal is good, I look at 'bar tilt, bar height, and bar reach. I have a "best fit" bike and I've taken to trying to transfer measurements over, but with vintage bikes its a bit of a pain to change out stems several times.

So I start with science, use my comfort to final-set the saddle and then just change the front end if it's convenient or really uncomfortable. Usually when I get to this point the position will be comfortable for 5 to 10 miles. As I find the limits I have to remedy the problems, then keep training up to the next comfort limit, and remedy that one. The farthest I've taken this process is to become fit confident going on two metric centuries on consecutive days.

randyjawa 

Sorry to confuse. The Torpado, often mistaken for a tornado, is the brown bike with red head tube and lots of patina. The black bicycle is a 1958 Rabeneick 120d, a high end German bike that I picked up a year, or two, ago. It is no longer black. The bike, when done, will sport a blue frame with gold head tube and fork. I am going to do the art work pretty soon, after I finish opening up my lake cottage, pile two cords of birch fire wood, finish installing a floor that I had to leave last Fall (I fell and banged up my knee pretty badly - spent the first six weeks in Jamaica riding an aluminum cane).

Anyway, the Rabeneick 120d as it is looking right now...

Piff 

What silly germans. Was that seat binder bolt position unique to that model/brand?

noglider 

@Piff, Legnano did that, too. It's one of their signatures.

merziac

That is beautiful, very nice.

+1 on PBH, it seems like nobody gets this right and goes on inseam, it is a far truer measure of how long this number should be and is rarely done correctly since it is "uncomfortable" to do, you must do it firmly to get the maximum reading.

RiddleOfSteel

And here I thought my general just-for-kicks-yet-sorta-alright formula was take your height in x' y" and make it centimeters. So I'm 6'5" (ok, it rounds up from 6'4.5"..., pants inseam = 34-35"), so I should ride a 65cm bike. That works out to be spot on. 6'4" on a 64cm, etc etc 6'0" on a 60cm, 5'11" on a 511cm frame, 5'10" on a hey wait a minute... But really, for 6'0" and up, it seems to be an alright metric, IMO.

I ride anything from 63-66cm. The taller ones are fine provided the top tube isn't stupid long in combination with a seat tube angle that doesn't mess that up. I prefer 63-64cm as the lower top tube allows more rocking-back-and-forth angle (between the legs, before hitting them) when out of the saddle accelerating or climbing.

I've given fitment, and more importantly (to me), fitment points, a lot of thought. We, or bike fitters etc, talk about all this stuff. Stack, reach, things from impossible to measure points to mythological points in space. Things that do not take into account huge an obvious variables. Stem length, handlebar reach, brake lever/brifter reach--all three are huge deals in cockpit fitting and length they can affect. Top tube length--what is our reference point or angle? All this stuff that OEMs don't seem to take into consideration, or if they do, ever communicate to the consumer effectively. '80s brake levers have super short bodies/horizontal lengths. New era Shimano and SRAM brifters (especially the hydraulic brake ones) are really long.

So I work from three dead-obvious points (or points of contact). A human rides this thing, not a ruler hovering in the middle. Points are: 1) center of crank or BB spindle 2) Sitbone point, marked at the centerline of the saddle 3) Brake/brifter lever hood kick-up/notch

For Point 1, I use the BB center because it's a fixed point to measure another critical distance. It doesn't move, or involve a rotating pedal at the end of a crank arm. My crank arm length constant is 175mm.
For Point 2, just behind the flaring out of the saddle is usually the place where the sitbones contact the saddle. If you draw a line from the right to the left bone, and mark along the centerline of the saddle, that is your X.
For Point 3, the lever hood kick-up point is where the webbing between your thumb and index finger goes. Your hand moves no further, thus it is a natural place to have a max measurement go to.

From these three points, I get three lengths: A) center of BB to saddle sitbone point B) sitbone to BB spindle setback C) sitbone to hood kick-up [if you ride in the drops only, or a lot, then measure the furthest point there]

For Length A, we do not measure directly up the seat tube. No saddle is identical, so a BB to sitbone point measurement eliminates saddle shape variance (length, scoopy-ness, sag, angle, etc)
For Length B, we plumb bob (I hang an extended tape measure) from the sibone point to some easy to mark or remember place on the chain stay. You could go from the floor, but the chain stay to BB is super easy to do.
For Length C, we go from the sitbone point to the hood kick-up. This covers all frame angle variance, top tube length variance, saddle-to-bar drop, stem length variance, handlebar reach and width variance, and brake lever body length variance.

For me, Length A is 32 1/2" to 32 5/8". Length B is 11 1/4" (ideally) to 11 1/2" (max). Length C is 36" max (35" minimum). Again, crank arm constant is 175mm. My max top tube length, normalized to a 73° seat tube angle (at my frame size, 1° of angle change = 1cm top tube length change), is 60cm. This allows me to employ a 100mm stem, thus keeping the proportion of the frame and components pleasing to my eye (critical for a designer!).

Saddles change, frame sizes change, cranks change, stems change, bars change, brake/STI levers change. The rider doesn't.

Dfrost 

Amazing, but it works for me!

I'm a very leggy 6’0” = 72”, and not very flexible anymore. My bikes, both very comfy for any distance, are 62cm and 61.5 (ctc), both with 58cm TT and similar ST angles. I’ve had the black Miyata 912 for over 40 years. It’s now more comfortable that ever, thanks especially to the Berthoud leather saddle on a seatpost that lets it get back far enough for my long femurs. Bars have been up near saddle height for about a decade. I measure between contact points much like RiddleOfSteel describes.

I’ve compared them using lots of photos, bikes on the trainer, camera on a tripod taking multiple shots while I’m pedaling, then checking myself against background details. This technique helps if something has been changed that could affect the fit.
‘K

Lascauxcaveman 

Of course! You're no idiot! Now let me tell you about my sure fire stock market investing tips...

Road Fan

I like it all! What do is the same geometry, but I don't have my target values fixed in my brain like you do. I'm getting there on your dimensions A and B, however. But a question: how did you decide that 35 to 36" is your target value for dimension C? So far once my saddle is good the bar us usually ok, but I usually don't have a methodology for tweaking it.

merziac

RiddleOfSteel

"The rider doesn't", that's funny lad.

Let us know about that in another 5, 10, 15 years.

RiddleOfSteel

Thank you! I sorted all these dimensions over time. Initially saddle height was from general bike fit guidelines and then I modified it over time. For saddle setback, some people are more sensitive to it, others not. It’s a generally organic process. You find bikes you like riding or find comfortable and if you care to, quantify it and repeat the fit on other bikes. Or at least measure the other bikes and see how they compare.

I reached the C value, again, after time. I remember starting off at 38” and tapered it within the first year or so of measuring that dimension. It was just a comfort thing. I dislike being overly-stretched out, but also notice when I’m too scrunched up.

This is where top tube length slowly came into play as comfort working in complement with aesthetics (stem length) and proportion became important. I end up being a bit of a numbers guy because absolutes are nice to have around. Reference points give the ability to compare and sort things out.

My measurements/points/distances are done in such a way that it can give myself (and others) a good starting point or a good target to aim toward. I want to be comfortable on a bike so that I can want to ride that bike and not grumble about it.

Now, going from the above Paramount to my ‘85 Allez SE with classic drop bars, ‘80s aero levers, and a 60cm TT, there is considerable saddle to hood drop (more than 2x! 1 1/2” vs 3 3/8”), so the comfort factor is decidedly different. The Paramount is set up for all-day, long ride comfort (touring), and the Allez for comfort enough but really for looking period correct (and going fast). The Allez ends up being comfortable enough because it looks so good and rides really nicely. Plus I can always ride on the tops of the bars and not on the hoods, thus enabling me to be more upright.