nun

I'm buying a traditional steel bike with a 74 deg seat tube and a horizontal top tube and I'd like to get the zeitgist on the size I should get.

I have a PBH of 81cm, I'm 5' 10" tall and ride with a saddle height of 71cm. I like to ride with the bars a few cm below the saddle, somewhere between a Fremch and Eddy fit. What size bike would you suggest

idcruiserman

56

nun

That's center to top, right

Randochap

It all depends. You're 5ft 10 and your getting a 74 degree seat tube? Why?

RFC

Yes, if you are thinking something of like a traditional crit bike, 56 TT would probably be right. Also, consider requesting a "tall" bike. That is, you want plenty of HT, so go for a tall TT. But, you really should consult someone who knows something. The following C&V bikes are examples:

1985 Club Fuji. 75 SA, 74 HA; 55cm TT; 57cm ST; Standover 32.5".



1985 Tommaso. 76 SA, 75 HA; 56cm TT; 56cm ST; Standover 32.5".



1989 Trek 660. 73.5 SA, 73.5 HA; 55cm TT; 55cm ST; Standover 32.25".

nun

What does height have to do with seat angle? If I was planning on touring on the bike then the seat tube angle would be relevant.

ericm979

Longer legs often means long thighs, so the seat has to be farther back to positon the rider correctly over the pedals.

A steep seat tube angle means that you will have the seat farther back, making the reach longer.

Loose Chain

You and I are the same height but I have an 86cm PBH or nearly so in bare feet and I ride a 55 or 56 ctc on my steel frame Pinarello and Gureciotti. I would think with the slightly shorter legs you could want a 54 or 55 ctc.

There is no exact frame size that is always perfect, most people can get along fine with a frame 1cm to either side of ideal. For shorter, fast riding like a crit you would tend smaller to enhance areo postion, power and quick handling and for long rides, and road racing and fitness riding I would go to the higher side to give yourself a skosh of room to move around.

DaveSSS 

I see a problem. You have short legs for your height. The comments about long legs don't apply here. I'm 5'-6.5" tall and my saddle height is 73cm or 2cm greater.

With such a long torso, you can probably ride any traditional frame that provides as little as 2cm of standover clearance (79cm). Depending on how the "size" is measured, that would be no larger than a 54cm c-c or 56cm c-t.

This is a case where a sloping TT frame might be a good idea.

scotch

get fitted. i'm 5'10" as well and always take a 58 for both traditional and compact.

superdex

Isn't this just the opposite?

idcruiserman

For KOPS, the seat would need to be back more with a steeper ST angle.

nun

I like what I'm hearing here, there's not too much of the super small recommendations that bike shops often do. I think I'll go with 1cm SO clearance (it'll be a bit more with my shoes on) so that the headtube is high enough that I can get the top of the bars to around 3 or 4cm below the saddle height. As I have an 81cm PBH that puts the SOH at 80cm. Using 26.5cm as the BB to ground height and with a 74 deg seat angle the c-to-c size will be

size = (80-1.4-26.5)/sin(74) = 54.2cm or 56cm c-to-t

My 71cm seat height means that I have 15cm from the top of the seat lug to the top of my saddle (measured parallel to the seat tube). The head tube angle is also 74 deg and assuming that it's top is at the same height as the top of the seat lug that means a steering stack up of 12cm will put me 3cm below the saddle.

NormanF

If you have long legs relative to your torso, a bike builder might give you a larger frame. Smaller legs the other way around. I'm 5'7" and GVH should have fitted me with a 53 but went with a 55 due to my having long legs. Bike fitting is not an exact science.

coasting 

i'm 5'10. i have long torso short legs. 30 inch inseam. i ride a 56cm top tube with 100mm stem and a 55 cm top tube with 110mm stem. both are fine

superdex

Agreed, but the way the comment is worded sounds as though the steeper angle moves the seat farther back, which is not true. Yes, I'm a part-time grammarian.