jimmuller 

Just a terminology question, really. What would it mean other than merely "top tube length"?

(I'm trying to decide how comparable a particular frame is to others I have.)

ThermionicScott 

It's a way to compare sloping TT bikes directly with the ones we know and love. (The actual TT length measurement is usually shorter than that.)

jimmuller 

Thanks. This particular frame is in fact a steel horizontal TT vintage bike. So I was just curious why the seller listed it that way. I wanted to be sure it wasn't something odd like inside edge to inside edge.

noglider 

I guess he's using the term out of habit.

nlerner

Maybe he meant "affective" top tube length and was trying to pull on your heart strings.

Spaghetti Legs 

Maybe a crash buckled the top tube, thereby making it a little shorter.

rhm

It's an ebay measurement. It's as useful as the paper it's written on. The (hopeful) seller used the word "effective" hoping the extra syllables would make his sale more effective.

The Golden Boy 

I suppose- sloping TTs are the norm- but the "effective TT length" distance is always going to be the important measurement vs the actual TT length and angle.

SJX426 

..... or else he meant the length will work for the buyer as in "it is the right length for you"!

jimmuller 

It doesn't matter. I put in an offer which was accepted. Details at 11...

due ruote 

The effective top tube length is the horizontal distance from the top tube/head tube junction to the seat tube. This measurement has become significant as more and more bikes are designed with sloping top tubes.

So I guess in the case of your horizontal tt new (what is it?) bicycle, ettl = ttl.

RobbieTunes

None of my bikes have an effective top tube length.
Due to their owner/rider, they are all ineffective.

verktyg 

Yes and don't forget... "Bike will fit someone 5'8" to 6'2".

Also.... "Super Rare Peugeot U-08"....

Sloping top tubea aren't new, they go back to the early days of cycling! I guess a Penny Farthing had a sloping top tube!

Top tubes were traditionally measured from the centerline of the seat tube to the centerline of the head tube. Due Route shows a good drawing of Effective Top Tube Length of a sloping top tube in message #11 .

Many classic frames were measured from the center of the BB to the top of the seat tube which made a lot more sense than center to center of a frame with a horizontal TT. Just add 10"-11" to the seat tube length and that would give you the standover height!

Doesn't work with sloping TTs.

verktyg

Chas.

cyclotoine

and reach will always be even more important, most manufacturers are on board with that one now.

The Golden Boy 

What's "reach?"

jimmuller 

Just for yuks I did some measuring yesterday. I've done the same measurements several times in the last few years and always come to the same conclusions, then promptly chose to ignore them. I had put a 90mm stem on the Masi and 80mm on everything else, since the Masi is nominally smaller. In fact the distance from the nose of the saddle (all the same but one) and the handlebar was within 5mm of the same for all except the Champion Team which was nearly 1cm longer. I don't recall ever thinking it was too long while riding it.

In the old days I never thought about it but maybe a decade or two (or three) ago I began to wonder if my UO-8 was too long. It doesn't feel too long now though, and its saddle-to-bar distance is about the same as the others. But it rides as if it were bigger.

When I first get on the Masi it sometimes feels smaller, not cramped but shorter. That feeling lasts all of about 100 yards before it feels just right. Since the longitudinal distances pretty much match the other bikes, the difference might be the saddle-bar drop, or the saddle-crank position. Anyway, it is more something wonder at than to worry over.

Addendum: I mis-under-remembered. The Masi is slightly shorter reach but the Gazelle is currently set up about 3cm shorter! Surprisingly it does not feel cramped at all. It does like to go fast. But then so do the Masi and the Motobecane.

Never mind. I don't know what I'm talking about.

exmechanic89

If I might ask.. why was it decided that top tube length is most important? In other words why the switch from seat tube length as the standard way to measure a frame? Was it because modern geometry uses sloping TTs? I was just curious. I've been back into riding for about a year from a long hiatus, and the way modern bikes are measured has changed.

jimmuller 

There are several ways to answer that. Saddle height can be adjusted easily so if the ST is 2cm shorter, well you just pull the seat post 2cm further out.

If all frames and people were built to the same proportions one could pick the appropriate ST length and the TT would scale with it. But neither bikes nor people are built that way!

The real answer is that the TT determines how stretched out your back has to be, how much weight is on your hands, how your weight is distributed front to rear, etc. You can't adjust the TT like you can saddle height except by swapping out the stem, and that has a few other side effects. You can move the saddle fore or aft on the rails but that also affects your knee position over the pedals and crank. (I think that is an overrated feature but who am I to argue?) So it's easier to start with an appropriate TT.

fietsbob

In design specs you run a plumb line down to the axis of the BB..

'Reach' is from there forward, 'Setback' is from that point rearward, dividing the top tube length...

The Golden Boy 

So then what does that have to do with this?

oldbobcat

The $64K question will always be, when my feet are on the pedals, can I get the handlebar where I want it to be? Reach (the x distance between the bottom bracket and the top of the head tube) and stack (the y distance between those points) is the most direct way of determining this. Since these measurements to not correspond to the size of any component of the frame, they are a relatively new component of geometry tables.

exmechanic89

Thanks for the explanation.

It's funny, I've had to replace the stem on every used bike I've bought for my wife and I except my '87 Peugeot Traithlon I recently picked up. Our other bikes are all early/mid 90's Trek mtbs, and every one of them had a crazy long stem - even my wife's 15.5" 930! I often wonder what designers in the 90's were thinking with these long top tube, long stem configurations. I'm almost 6ft tall and I was still WAY too stretched on both my 950s before I swapped out the stems to something shorter. They all fit well now, but of course it was a PITA since none of these bikes had threadless stems, lol.

dddd

One more little wrench that can get thrown into the works is the reach of the handlebar, actually the reach and the drop measurements.
Especially since the fit while riding in the drops will determine the maximum permissible distance from saddle to bars, the bar's reach and drop are critical to the equation.
I usually bring the saddle well forward on the post in order to make for a comfortable reach to the drops, since I usually start with a fairly long stem on a good-sized frame in order to achieve enough forward lean while attacking steep inclines.
It sure makes my day when a "new" bike purchase already has the right stem and bars for the frame size.

Riders who spend much of their riding time with their hands on the hoods of integrated levers would likely want to shorten the combined reach of their frame, stem and bars, since the hoods act as a substantial reach extension.

Back in the mid-90's, it was unbelievable how much that the riding characteristics of typical "cross country" mountain bikes could be improved just by finding (not so easy) and installing an appropriate riser-style handlebar with considerable pull-back. I seemingly became a better rider overnight once I made this change to my racing bike. It was like the marketers had perhaps envisioned riders racing these bikes for long periods over flat ground, so typically installed 135mm or longer stems with straight, narrow bars. Maybe it was just because the pro's could ride them that way.

mstateglfr 

Once in the last dozen+ bike I refurbished and sold, I didn't list a height range suggestion.
A 5'8 college kid showed up to see a 65cm bike with a 36" standover height.

Listing a typical height range saves everyone time.

gugie 

So what would be an ineffective top tube length?