What frame size do you ride

[freiston]

55cm and I'm 5'9" with a trouser-fit inside leg of 32". I consider the size to be good for me. I reckon I could go smaller comfortably but certainly not larger.

It's the one in my avatar picture (and posted elsewhere on these boards)

Full frame geometry (inches/mm):

CENTRE of BB to TOP of TT = 21.57/548
EFFECTIVE TT LENGTH = 21.93/557
HT ANGLE = 71.5 ̊
ST ANGLE = 73 ̊
CHAINSTAY = 17.32/440
WHEELBASE = 40.90/1039
FORK RAKE = 1.97/50
BB HEIGHT = 11.26/286
HEADTUBE = 5.91/150
STANDOVER = 32.56/827

Stem is 105mm and the cranks are 170mm.

 

[CanucksTraveller]

I'm 6 foot; I ride a 58cm Trek hybrid which feels like a very tall frame rather than long, (I feel like I'm on a penny farthing and I have to slide off the saddle at lights if there's no curb to rest my left foot). It's a standard stem and the reach is good so it's the right size probably.
I also ride a M/L size Giant which I find a little more comfortable overall height wise, but then it's a compact geometry which may be a factor. The reach on that one is also fine.

 

[GuyBoden]

I'm 6'1" and I fit on frames with a 59-63cm seat tube (measured centre of bottom bracket to top of seat tube c-t). Any horizontal top tube (or imaginary Top Tube) shorter than 57cm c-c and I feel squashed.

This size is based on the measurements by Ron Spencer, when I bought one of his custom road bikes in the early 1980's, but it wasn't called a "bike fit" in those days.

Unfortunately, my custom Ron Spencer road Bike was stolen many years ago, but it looked like this.

 

[cyberknight]

[QUOTE 4506703, member: 9609"]What measurement is everyone talking about ? centre of bottom bracket to top of seat post ?[/QUOTE]

Normally centre of bottom bracket to centre of top tube, but some manufacturers tweak it.

I thought bike sizes were by virtual top tube as the differences in compact, semi compact and traditional frames muddy the waters so much.

 

[mjr]

I thought bike sizes were by virtual top tube as the differences in compact, semi compact and traditional frames muddy the waters so much.

Yebbut sloping top tubes are ugly and should be shunned

 

[freiston]

Yebbut sloping top tubes are ugly and should be shunned

Unless you're a girl

 

[Hacienda71]

6'3 58 or 60cm

 

[fossyant]

I'm 6 foot; I ride a 58cm Trek hybrid which feels like a very tall frame rather than long, (I feel like I'm on a penny farthing and I have to slide off the saddle at lights if there's no curb to rest my left foot). It's a standard stem and the reach is good so it's the right size probably.
I also ride a M/L size Giant which I find a little more comfortable overall height wise, but then it's a compact geometry which may be a factor. The reach on that one is also fine.

I'm 5'9" and ride 54cm new frames/56cm old 'skool'. But I get you there about feeling high, but that's only on my new 27.5 MTB - good god, I nearly need step ladders. High MTB BB, big wheels, it is a big bike !!

 

[Ajax Bay]

FORK RAKE = 1.97/50

It's not 'rake' it's 'offset'. Rake, if used, is an angle: the same as the head tube angle. Offset is a distance: in your case 2".

 

[CanucksTraveller]

Yebbut sloping top tubes are ugly and should be shunned

How very dare you. Mike Burrows' TCR design paved the way for much increased stiffness and lightness for most of the tour pro bikes today, and the sloping design is a modern icon.

(However I note the smiley, and aesthetically, nothing beats a 1980s Pinarello or Colnago for me!)

 

[RedRider]

<<<that bike's 59 square, there's about seven or eight fingers of seatpost showing with I think a 110 stem. It fits great and I'm 6'3.
I find bike geometry / fit a bit of a mystery. Currently on the lookout for a second hand frame/bike for a fixed gear winter ride / commuter. I like to feel stretched out but do I need to wait for a long top tube ie 58-61 or could differences in angles etc get the fit i like?

 

[freiston]

It's not 'rake' it's 'offset'. Rake, if used, is an angle: the same as the head tube angle. Offset is a distance: in your case 2".

I just quoted the manufacturer's data sheet. Other sources use rake and offset interchangeably and give distance not angle to quantify it:

"Fork rake or offset is the distance between the steering axis and the wheel center. It doesn’t matter if the fork blade is curved forward in the traditional way, or if the fork blade is straight but angled forward from the crown. If the offset is the same the bike will handle the same."

"Bicycle forks usually have an offset, or rake (not to be confused with a different use of the word rake in the motorcycle world), that places the fork ends forward of the steering axis."

"The "rake" or "offset" of a fork is the distance between the wheel axle and the extension of the steering axis. This may be accomplished by bending the fork blades, or by attaching the fork ends to the front of the blades, or by tilting the blades where they attach to the crown."

Edit: Following the footnote link in Wikipedia, there is another article which says:

"The fork offset is the perpendicular distance from the steering axis to the center of the front wheel.

In bicycles, fork offset is also called fork rake. Road racing bicycle forks have an offset of 40–50 mm (1.6–2.0 in).[6]

The offset may be implemented by curving the forks, adding a perpendicular tab at their lower ends, offseting the fork blade sockets of the fork crown ahead of the steerer, or by mounting the forks into the crown at an angle to the steer tube. The development of forks with curves is attributed to George Singer.[7]

In motorcycles with telescopic fork tubes, fork offset can be implemented by either an offset in the triple tree, adding a triple tree rake[8] (usually measured in degrees from 0) to the fork tubes as they mount into the triple tree, or a combination of the two.[9] Other, less-common motorcycle forks, such as trailing link or leading link forks, can implement offset by the length of link arms."​

 

[freiston]

<<<that bike's 59 square, there's about seven or eight fingers of seatpost showing with I think a 110 stem. It fits great and I'm 6'3.
I find bike geometry / fit a bit of a mystery. Currently on the lookout for a second hand frame/bike for a fixed gear winter ride / commuter. I like to feel stretched out but do I need to wait for a long top tube ie 58-61 or could differences in angles etc get the fit i like?

I'm no expert but everything plays a part - angles affect tube lengths which affects angles etc. You need to think of where the pedals are in relation to the head tube as well as where the saddle is. "Reach" in a frame is the distance from a point vertical of the centre of the bottom bracket, horizontally to the centre of the top of the head tube. So the head angle will affect reach, the seat angle (together with seat rail position) will affect your centre of gravity and both will affect (effective) top tube length. Stem length will affect your riding position too. The general rule is to sort out your seat position/centre of gravity relative to your pedals and then start tinkering with handlebar height and stem length. I would think that a longer effective top tube would also mean a longer reach and I assume that by stretched out, you mean more forward with a long torso - which would necessitate the saddle going back to 'counterbalance', but I'm no expert and I would advise you to do more research/get more opinion - and I dare say there are many very varied opinions

 

[Ajax Bay]

Apologies for being off thread topic.
Various demonstrations of misuse of 'rake', or acknowledgement of widespread (misinformed) misuse as an alternative. 'Rake' sounds like an angle, don't you think? 'Offset' is definitely a distance.
Using them interchangeably makes for poor communications - that's the point. Offset can only mean one thing. Rake has many meanings, of which its misuse for 'rake' is but one.

Wikipedia on "Rake"

• Rake, the caster angle of a bicycle or motorcycle
• Rake angle, a parameter in machining and cutting geometry

The first leads to the same wiki and offers:
The steering axis angle, also called caster angle or head angle, is the angle that the steering axis makes with the horizontal or vertical, depending on convention. The steering axis is the axis about which the steering mechanism (fork, handlebars, front wheel, etc.) pivots. The steering axis angle usually matches the angle of the head tube.

Steering axis angle


Telescopic forks on a BMW motorcycle reveal the steering axis angle, also called the rake angle


Example of a chopper with an unusually large rake angle

 

[HLaB]

Yes sorry its a Kinesis Racelight T2 and I have fitted a shorter stem and messed around with seat height and seat position

Doesn't sound too big to me I ride a 54cm T2 but I'm only 5 foot 9 inches.