dim

I'm on the market for a good used road bike, but will be buying 2nd hand off ebay, and most probably will not be able to view/ride the bike before buying.

I currently ride a 19 inch Ridgeback Comet (2008 model), and that is as big as I can go..... (not much space between the top tube and the top of my seat)....any bigger and I will have difficulty when stopping at a stop sign or traffic light

I came accross this bike calculator .... can anyone comment if these calculations are good?

Bike Fit Calculator | Find Your Bike Size | Competitive Cyclist

dim

so, looking at my specs, and looking at the bianchi geometry sizes for a Via Nirone, what size bike do I need?

here are my specs from the calculator (if you click on the link below, it shows a diagram of the bike geometry):

https://www.competitivecyclist.com/Store/catalog/fitCalculatorBike.jsp#results

and here are the specs that was emailed to me (minus the frame diagram)

[TABLE="class: ecximageblock, width: 270, align: center"]
[TR]
[TD]Your Measurements[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Inseam:
Trunk:
Forearm:
Arm:
Thigh:
Lower Leg:
Sternal Notch:
Total Body Height:[/TD]
[TD]74
61
39
66
58
54
143
170[/TD]
[/TR]
[/TABLE]

[TABLE="class: ecximageblock, width: 280, align: center"]
[TR]
[TD]The Eddy Fit (cm)[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Seat Tube Range c–c:
Seat Tube Range c–t:
Top Tube Length:
Stem Length:
BB–Saddle Position:
Saddle Handlebar:
Saddle Setback:[/TD]
[TD]49.1 - 49.6 cm
50.6 - 51.1 cm
56.6 - 57 cm
10.1 - 10.7 cm
66.3 - 68.3 cm
54.5 - 55.1 cm
2.9 - 3.3 cm[/TD]
[/TR]
[TR]
[TD]The Competitive Fit (cm)[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Seat Tube Range c–c:
Seat Tube Range c–t:
Top Tube Length:
Stem Length:
BB–Saddle Position:
Saddle Handlebar:
Saddle Setback:[/TD]
[TD]47.9 - 48.4 cm
49.4 - 49.9 cm
56.6 - 57 cm
11.2 - 11.8 cm
67.1 - 69.1 cm
53.7 - 54.3 cm
1.7 - 2.1 cm[/TD]
[/TR]
[TR]
[TD]The French Fit (cm)[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Seat Tube Range c–c:
Seat Tube Range c–t:
Top Tube Length:
Stem Length:
BB–Saddle Position:
Saddle Handlebar:
Saddle Setback:[/TD]
[TD]50.8 - 51.3 cm
52.3 - 52.8 cm
57.8 - 58.2 cm
10.3 - 10.9 cm
64.6 - 66.6 cm
56.2 - 56.8 cm
2.4 - 2.8 cm


[/TD]
[/TR]
[/TABLE]


and here is the Bianchi geometry chart:

bikebreak

if you are 170cm tall, ie almost 5'7", you should be looking for a road bike in 52-54cm. With inseam 74cm, you may have shortish legs and longer torso and should go longer on top tube or stem to compensate. So a size 53 would work. The calculator seems to want you on a smaller bike, but a relaxed Eddy fit calls for a longer taller frame.

I am about the same height and have been on bikes ranging from 49-56cm, and fit best on 52-54. I also prefer a sort of Eddy fit, meaning longer top tube and less drop from saddle to bars compared to modern race fit.

Reynolds 

Here's another simpler calculator. This guy is a master framebuilder an knows a lot abou t fitting:

Dave Moulton's Blog - Dave Moulton's Bike Blog - A Different Thought on Frame*Sizing

Maelochs

Interesting that this came up, asd I am wrestling with frame size for an online purchase.

My experience is that it is safest to buy a little small rather than a little large. A longer stem and seatpost and a set-back saddle are all easy to manage. Compressing a too-tall or too-long frame is impossible.

I am going to check out that calculator.

What I have been doing is getting every possible measurement from the bikes I have and comparing them to the geometries listed online. One problem with geometry charts is that they don't always give all the measurements need. How about reach and stack? Seatpost top setback from bottom bracket (one of the few things that cannot change is the saddle-bottom bracket distance--most bodies works best with one relationship between pedals and seat.)

It will always be a risk, but not a huge risk, so long as you know your preferred posture on a bike and don'
t buy too big (no matter how sweet the deal financially.)

chasm54

Try the "Fitting Your Bike" sub-forum.

McBTC

Interesting... the calculations accord with my personal experience as far as desired c-c frame size but, I don't see the length of foot as having anything to do with it as I don't see that foot length serves to lengthen the leg at the bottom of the stroke because I don't ride with my toes pointed down.

Gweedo1

So what ever happened to the old method of figuring out your size, using which ever method you prefer, but then getting the next smallest frame size as the way of choosing the right frame for you?

Reynolds 

Some ride heels down, some toes down, some neutral. However, I trust Dave Moulton's experience because it's based on hundreds of actual fittings and not in some theory. As stated, this chart is intended as a starting point.

McBTC

Except that short people do not have long feet and tall people, short feet -- height are foot length are in fact positively correlated.

Calla lily

I'm not sure that's true. My friend and I are both 5'2". I wear a size 5-6 women's shoe. She wears a size 10 women's.

dksix

It's showing that I need a 61CM c-t seat tube but a 56CM top tube which might explain why the 120mm stem felt horrible and I ended up going with a 90mm. I've felt that a 61CM is the right size for me, since buying a 60CM but always wondered why I needed such a short stem. I guess I don't really know why but this goes with what felt the best out of the 3 stems and 2 seat post I've tried. But over all I've got everything that's adjustable within the ranges. Thanks to the OP, I had never found one that comprehensible.

Maelochs

I am 6'1" but I have the legs of someone 6'4" and the torso of a person 5'6' plus the arms of an orangutan. I have a variety of frames---from a 50 cm Dawes to a 61 cm Cannondale, all of which sort of fit. On the Dawes I have a lot of seatpost exposed (bought an bargain-basement closeout extra-long carbon post---love it) and on the Cannondale a couple inches exposed.

I am looking at either a 54 or 56 frame from my next bike---anyone would tell me I was a fool and needed 58 cm at least, but from all the math and measurements and drawings and schematics I have done, it looks like a 56 cm frame with a 90 mm stem would be about right or even a little long for me, particularly depending on bar shape. With my long arms I can reach way forward, but with my short torso I have to bend too far and get too much weight forward, and end up using my hands to support me too much.

All the "fit systems" are fine until they run into real people, some of whom have giant or tiny feet or limbs or torsos, and all of which have different comfort zones, optimal power output postures, and flexibility.

I know this can be a morally difficult issue, but if you ever give any business to the local bike shop, go there and test a few frames to get some idea of what works for you.

I won't do it because I do all my own mechanics and buy all my parts online and don't want to abuse them, but I would certainly recommend it to everyone else, if they feel comfortable doing it.

Better still, go to a big store with a bike department and test-fit yourself to some bikes there.

dim

update....

I sent Bianchi an email with my measurements, and they have advised me to get a size 53

mapeiboy

Problem solved .

ltxi

Understand that. My "ideal" road frame size is 58cm and, tho recognizing 56cm would also work, that's what I've for the most part always ridden. But I've also always needed a short reach stem to make that size work....prefer a more upright, touring position, but still. Projecting toward next year, I've recently been thinking about moving to a 56cm frame. N+0--sell off the vintage backup and add new as a primary. It does take some consideration, tho, as as I don't do cheap/really inexpensive bikes. Thanks for the post...it helps/reinforces my thoughts.

smith_Jr

Knowing the correct frame size is so important before buying any bikes. If you want to ride comfortably you need a bike that is suit based on your height. Only correct frame size bike can give you more pleasure when you riding.

I got a brand new bikejar bike size calculator on their resource. It works fine for me, and I think it will be the good solution for everyone. You can try their bike fitting calculator. it's super easy to use. They have also a video tutorial on how to use this calculator. So you can check their brand new calculator. Thanks for the thread.

I will come back soon to see the update here. Till then take care yourself. happy riding.