mstateglfr 

yeah Miyata was mentioned, but a bunch of other Japanese road frames from the 80s had top tubes that were relatively short.
My 63cm '87 Miyata 912 had a 57cm top tube. Just goofy short as a general length for that size frame, but it works for some!
A 60cm 912 had a 56cm top tube.

chain_whipped

seagrade 

King Alf’s Shorter frame looks shorter than any other frame…

Minimal clearances and so little fork rake it’s probably nearer pedal overlap than toe clip overlap.

24/24 wheelset with large flange Record hubs. Received wisdom in the early 1980s was that although slightly heavier, large flange hubs provided more effective power transfer through slightly shorter spokes. By the late 1980s they had largely disappeared from pro road racing with one or two exceptions, including Robert Millar who used set built by UK master wheel builder Pete Matthews on special occasions etc.

Kontact 

My experience test riding a lot of customers' bikes has suggested that the height and width of the bars/hoods can have a large effect on both responsiveness and steering feel due to both front end loading and leverage from the saddle.

So it would have been interesting to have a particular position you tend to, and then made sure that 57 was right at that position.

chain_whipped

Moove aside, here comes cowbells~
We've mostly all seen those limit lines stamped into seat post and stems. So Mister Speedo, if you want to ride to the limit's set your seat post and stem to their limits!

jamesdak 

I did, the Ciocc went through several variations of setup trying to find what felt right to me. I really wanted it to work. But at least the bike wound up with a taller mechanic friend from my LBS and he's totally loving it.

Maybe deep down I wanted it to fail so I could justify getting one of those new and beautiful San Cristobal's!

non-fixie 

Luckily Chris Juden of Cyclinguk.org has done all the legwork: A guide to rear shifting. A bit of a read, but worth it.

The older Ergo shifter shapes tend to blend in better visually than the current models. Trying to stay with the topic: here's another big one that came out rather well, if I say so myself:

Germany_chris

I'm not a proportional 6'2" with a 31" inseam w/ cycling shoes so I need some reach/effective top tube the problem with small frames for me is I feel like I'm riding on them not in them.

52telecaster

What a beauty!

Andy_K 

While there certainly are those for whom range of motion is a limiting factor, for me the high handlebars and short stem are all about weight distribution. You wouldn't guess it by looking at me, but I'm quite flexible. My trouble is that I've got a lot of weight above the waist, and it doesn't take much leaning forward before I'm tipping over.

Garthr

I prefer frames with a certain front center distance, at least 66cm for example. That makes the majority of ready made frames too short/small. As noted, the seat tube only matters if I'm after a certain sloping or level top tube.

Of all the frame photos I see posted here I don't see any that on their own, without the rider, look radically out of proportion. Of course bikes don't ride themselves though. In contrast, I've seen some "inches above the saddle" on many Rivendell's though.

For example here, quite high bars and a too short for me front center. A no go for me on both accounts. (Not my bike, a stock Rivendell photo as an example). Others may find it perfect.



I've ridden my custom Franklin road bike with bars that placed my hands a couple of inches above the saddle height like the bike above. That steering/handling is notably unnerving being that high. Conversely the lower I go, with drop bars well below saddle height, the same frame steers/handles beautifully, intuitively.

georges1

This my smallest MTB frame 17 inch, (normally I ride 20-21 inch frames) which I adjusted to my size thanks to a high rise stem and proper seat post

I also have this CT Wallis in size 52 because of its tubing which I will make work other wise 56-57cm is what I ride on road bike frames

AdventureManCO 

Your avatar makes a little more sense now!

Andy_K 

AdventureManCO 

To help me, and maybe others, understand, could you explain your working definition of 'front center'? I'm trying to picture it.


A few posts above, I posted a picture of this bike:





I'm starting to put together pieces of the puzzle. I took some measurements, and compared them to my other bikes. For the above bike: The seat tube is 20.5" or 52cm. Here's where it gets interesting. The top tube is a solid 21.5", or almost 55cm. When measuring a bunch of other bikes in my garage for top tube length, most are right around 22" on the dot, like the Treks, the PX-10, the Paramount...the bikes that I consider a 'great fit'. The longest top tubes I measured was 22.25", which were found on the Ironman and Super Course. I had a few other bikes in the garage that had about the same 21.5" top tube, namely the PXN-10 (in size 54cm) and the Trek Multitrack 950...which I consider a GREAT fitting and riding bike.

Then I started measuring overall wheelbase, and this bike is right around 40.6". Most of the other bikes I measured were right around there, or actually less. It sort of makes sense, given that this is bike geared towards touring, so I imagine it was designed with a longer wheelbase. I have less toe overlap on this bike than I do the IM.

The thing I'd like to play around with on this bike would be the stem. Not only is it really high, but it is actually really short as well. I wonder how a Technomic would do on it - something a little more like a 70-80mm stem, and perhaps a little lower. I'd be curious about how that may affect body position, and ride stability. Also, it seems like hooded levers can make a huge impact on fit as well, with older levers reducing the overall height of the hoods in relation to the saddle, compared to modern levers, which come straight out at the start of the curve down of the handlebars.

Also, I can totally understand what @merziac is saying about how he was describing the fit of a smaller bike with longer seat posts and stems, thanks for explaining that. It would seem to be magnified on frames on the much larger end of the spectrum, where tubing flex (whether frame or components) come very much into play.


With this bike above, it seems like we are in the ballpark. The biggest issues seem to be the goofy look of the high bars and weird stem, and therefore also the potential bar position being closer to the rider and affecting this 'front loading' or 'front center' measurement. It appears as though we may not be as 'front loaded' as other bikes due to the upright position caused by the stem, which is actually the inverse of what one might think a 'too small' frame would produce, so now I'm really curious to see what a different stem would do.

nlerner

Rather than use top tube length as a key measurement, figure out stack and reach of the bikes you feel fit best and use those figures as a starting point:

mstateglfr 

Stack and reach? Quit spewing that modern blasphemous junk!
Who cares if it helps immensely and is easily applied? This is c&v where ill-fitting bikes are coveted and praised in a perpetual echo chamber of bliss.

dddd

Years ago, and occasionally to this day, I would want to compare different bikes "handlebar reach", but without the benefit of any published reach figures.

So I would find an inside corner adjacent to a hallway, where two walls meet. I could then position the crank bolt center with the corner and measure forward to the handlebar from a spot higher up in the corner edge.

These days, I more often rely on my database of frame angles and with a little trig I can determine the effect of a bike's seat tube angle on the sum of the effective top tube length plus stem length.
Using published "reach" dimensions, some trig is still needed to correct for any difference in the "frame stack" of any two frames being compared.

Kontact 

You don't need trig. It's 3mm of reach for every 10mm of stack for anything in the range of road HTAs.

And 1cm per degree of seat tube angle difference is a good enough approximation for most bikes.

thinktubes 

repechage

keeping in mind that the position of the bars with a quill stem or a thread less assembly can vary, one may have trouble achieving equal, left out is the position of one’s hands on the hoods. Keep that in mind.

builders decide on a seat tube angle. One has to decide on what the builder has provided vs what one wants or needs.
I will leave to last the saddle brand, shape, size and how one perches on it. I think a significant error can be found if one does not keep track.
to do that I really think an assistant is needed.

mstateglfr 

Stack and reach are measurements that remove all the variables you mentioned, and the removal is great since it standardizes things.
After you have a stack and re ch, you can then figure out the stem length and bar shape/measurements that put your hoods where you like. Since levers are different lengths too, it makes great sense to remove all those variables and let the individual just figure those out after the standardized frame numbers have been set.

squirtdad

I am confused or ignorant, but where does seat height and seat to middle of BB fit in?
this was an area of detail in when building my Kirk and I ended up figuring out I did not have seat high enough
thx

nlerner

Seat height is a function of how high you set it or your leg length, not the frame itself. In other words, my seat height is always 73cm, whether that’s on a 19” frame or a 24” frame.

repechage

and that is my point. Stack and reach are useful but not enough. Setting aside crank length +/- 5 mm for the most part, where the saddle is placed for and aft are a function of femur, foot, pedaling style (think Coppi vs Anquitel and throw Bartali in for fun). Saddle shape will set one at a basic place on a saddle, that often is not the same displacement from the nose of the saddle. Once the saddle height and displacement behind the bottom bracket are accounted for, then that gets one to a stem length keeping in mind the bar shape.

in other words If I change saddles, say a 70’s Cinelli to a Brooks Pro or swallow, I have to confirm my relationship to the bottom bracket. I can tell you for me it is about a 10mm difference. That tosses in my view that saddle position can be just be set from hard points. One needs to be on the bike. I will add the ‘feel’ and a side view from a distance, think telephoto lens, will show one off the bike what is going on. A video while on a trainer can be even better to show the dynamic interaction.