junkmanj

Hi:

I've starter a training program for a half marathon and a component of the program is cross training; cycling in my case. I've run marathons is the past the last being in 2005. Since then I really porked up (185#) and would like to get back in shape.

The bike I'm using now is my son's Trek mountain bike but I would like to buy a road bike. To this end, I looked at various web sites to determine what frame size fits me. I'm 5'5-1/2" with a true inseam of 32". From the calculators I have found, the average frame size I need is 53 cm center to center and 55 cm center to top. It also recommeded a 170 mm crank length,

My aim is to purchase a used bike preferably a steel LeMond or similar steel road bike for around $800 - $1300. The question I have is as follows.

Can I rely on the frame calculators since a lot of bikes have different geometries? One web page suggested that the standover height should be 2" or 5 cm lower then the true inseam; is this reliable information?

I'm thinking to just go to different bike stores and test ride a few bikes although this is difficult now winter has arrived.

I would very much appreciate any help or advice. Thanks !!

Jim

stapfam

32" inseam at your height seems long but then I am 5'6" and have short legs. Frame size of 53cm is a good starting point but that is all it is-A starting point.

I take it you have not ridden a Road bike for some length of time so do not know bike set up yet. The main point about that is that it "Must Fit"- obvious- but must be comfortable.

Top tube length is normally the measurement to go by as this is a fixed size on a bike. Standover height will not affect fit until you get off the saddle and stand up so is not that imortant. Saddle and bar position can be altered.

Choosing the right size bike is an art that takes several bikes to get right and is relatively easy. What is not is finding your Local Bike shop (LBS) that will give you all the help possible to get somewhere near the right bike first time out---So first find your LBS.

Sorry to throw a few more problems at you- but only one person can get the right bike for you-- and that is you-----But hopefully with the help of a good bike shop.

And I ride several bikes- all different sizes but they do fit me- Some fitted off the shelf and some had to have a few parts changed to get right. And you cannot rely on a 53cm frame fitting you as good as another manufacturers 53cm frame- you might need a 51 or even a 54.

Go dog Go

Two ways to look at this:

1. Don't sweat the fit, get something close and enjoying riding. Over time you may fine tune the fit as you learn more and follow the 'right' advice.

2. Sweat the fit and soon realize that inseam alone is a poor indicator of frame size. Waaaaaaaaaay [did I say way?] more goes into getting a proper fit then that. Looking at how some "experts" fit bikes it's clear they know little more then inseam/stand over when they "fit". Foot size/torso length/arm legnth/your flexability/frame angles/etc. etc.etc. all go into the right fit for you. The more you know the harder it is imo.

I suggest #1.

junkmanj

Hi Stapfam:


Thanks for your advise. The LBS approach may be best in my case to ensure comfort. There are many LBS's in my area so I'll ask around to see which ones who are knowlegeable and helpful.

Best,
Jim

junkmanj

Thanks Go dog Go

I have an engineering background and tend to over analyze so I get your point #1. I guess if I wind up buying a used bike at a great price, I can change some components to fit and esentially use this as a work in progress and learning process.

Cheers!

tsl

My LBS's take on fitting is that it's so important, they won't let anyone test ride anything until after they've been fitted.

Find an LBS like that.

As for the inseam method of ballparking it, it depends on two other things as well--torso length and foot size.

Torso length determines the "reach" from the seat to the bars. I find that to be the more important measurement, and it's a lot harder to adjust this since changing stems also affects bike handling.

Until recently, I hadn't considered foot size. A custom frame builder on another forum explained that when we pedal, we extend the ankle, which makes foot length a consideration in saddle height. The proof is that extending the ankle activates the calf muscles, and cyclists as a group have huge calf muscles.

If I went purely by inseam, I'd be in a 58 or 59 cm frame. But my gangly limbs are attached to a short torso. A 55 cm top tube fits me best. Of course I need an extra-long seat post to go with it.

stapfam

Most on this forum have seen these pics but just to show how different frame sizes can be made to fit.

Giant's use a compact frame that covers "Several" Frame sizes. I ride an "Extra Small" (XS) a Small and a medium. The XS frame fits from 46 to 51. The S fits from 49 to 54 and the medium I have no pics of in fitted form but is larger.

I reckon that my frame size is a 51 and the gold bike is that size. All these bikes fit me but the Black OCR did have to have a few parts changed to make it comfortable- But none of my bikes fit like the Gold bike- but that was a custom build on a race fit frame.
B3.jpg Giant OCR in XS size- Long seat post and longer high rise Bar stem

B1.jpg Giant TCR-C in S Size- Nothing changed except the saddle

B2.jpg Boreas Ignis in 51cm- All parts selected on initial Build.

junkmanj

Hi tsl:

Probably will go get fitted at a LBS and spend the coin to by new. One of the calculators did account for torso, reach, lower leg lenth, etc. but not foot size. What you say makes sense. I would also imagine that standover height has some importance especially for a newbie that anticipates frequent stops.

Thanks for your post.

jim

BluesDawg

Best bet is to go to a bike shop and at least sit on a few bikes around the size you think you need. You might even get lucky and find something you want. Top tube length is the most important measurement. Sounds like you have long legs for your height, so be careful not to get something too long in the top tube. You can make minor adjustments with a longer or shorter stem, but you don't want to do anything extreme.

stapfam

Stand over is not important. Correct fitting should put the saddle at the right height for effective pedalling and at that height- you may not be able to touch the ground when seated. When this is coupled with TT length for reach- that top tube may be a bit high for you. No problem- you just do like the rest of us and lean the bike over when you come to rest.

Now if it was a mountain bike--- Then 4" clearance is the Norm and that is still often not enough.

bobthib

True, BUT....

You don't even want to get a bike that's too tall

Most bikes now have "compact" frames rather than the classic flat top tube, and that's why S.O. height is not so important.

junkmanj

Hi BluesDawg

I've decided to go to a few LBS's and swing a leg over. BTW, I used to spend time in the kaolin fields in Sandersville. When I travel from Atlanta to Sandersville, I always stop at the donut shop and bakery in Miligeville. They have the best donuts!

Mariner Fan

Lemond bikes are kinda different than most. They have a long top tube length and you really bend over to ride them. That's good for the racing types but if you want to sit a little more upright, it's not going to happen. I'm 6'3" and ride a 59 cm Lemond. All my Vintage bikes are 63 cm.

BluesDawg

I do a lot of riding through kaolin country. Occasionally to Sandersville (Linton Road is a favorite), but often around McIntyre, Toomsboro and Gordon which are closer to where I live in Coopers. Great roads when the chalk trucks aren't running.
I can't say that I share your enthusiasm for the bakery or its donuts. Try Blackbird Coffee around the corner for good coffee and scones.

junkmanj

Hi: Thanks! I was not aware of the racing geometry. I'm still considering a steel frame bike maybe a Jamis Quest or something similar. Nice bike by the way.

jppe

Jim-Engr here as well and you are asking the right questions. Good for you.

Based on data I've seen, I suspect your inseam is much longer than the average person's for your height. However, long femurs were a big advantage for distance running as you probably know! But, having the longer legs is going to be trickier to fit you onto a road bike. I would start with the frame size needed for your leg length. However you might need to shorten the stem some to keep your reach within reason. You can get a good Ritchey alloy stem for $70 so you might keep that in mind when looking at used bikes. Avoid going with too long a reach-it can cause all kinds of joint and discomfort issues on longer rides (lessons I've learned the hard way).

One of our LBS's will do a fitting for $70 which can give you the measurements you need to work off of. That might be an option if you have someone around you feel comfortable using. Having their information will take a lot of the guess work out of the selection process plus you can use it as a basis for years to come. But then again many of us Engrs tend to want to research all this ourselves and take the information we learn and just do things ourselves!!

Best of luck regardless of the approach!

DnvrFox

It wasn't very important when the top tubes were flat, either - especially on a road bike.

DnvrFox

I don't race - at all - but I have short legs and a long body - another reason to buy Lemond, which is what I have.

Road Fan

I think 32 inches is not a bad measurement. I'm 5'5 1/2" and mine is 81.4 cm. 32 inches, if exact, is 81.3 cm.

Standover height is no longer really accepted as the best way to size a frame, but there is such a think as a top tube that is too high for you. On a big enough bike you will make painful and perhaps harmful hard contact, unless you have developed a special skill to dismount fast, or to stop on one foot with a leg raised. Not recommended for a new returning cyclist, and really, why would you? I think the absolute upper limit is as follows: assume the thickness of your shoe heel is 1 cm. Add your inseam, in your case this gets 82.3 cm, again if 32 is exact. If its not, you want to round this number DOWN to 82 cm. If you straddle a bike with a top tube including the rear brake cable routing at this height off the ground, your body (ahem) will make contact, but not a hard bruising contact against hard parts of your body, such as pelvic bones.

Tob tube length is significant, but so is seat tube angle, and the position of the top of the headset above the ground, relative to the top of the saddle when set, from the ground. There's a lot more flexibility in adjusting the saddle height than the handlebar height, so some say that top tube length is much more critical than seat tube length. Too long and your bars will not be low enough. Too short and your bars will be too far below the saddle for you.

Seat tube angle places you farther behind the pedals, interacting with the seat post setback and to some degree with saddle design. Here we bridge into opinion: do you place your saddle the same distance behind the bottom bracket for all of your bikes, regardless of purpose or style? My opinion for my riding is yes, but others do not agree. But with a more laid back seat tube, I want a longer top tube for my style.

This degree of interaction says one of two things: buy and set up a bike, even a used one, with the aid of an LBS who will fit you to the bike during and after purchase. Or, it says, get something somewhere has a seat tube or effective seat tube around (in your case) 53 cm center to center, and maybe a cm or two more if you can stand over it and if you need a higher head tube end, AND get assistance to fit it to you. Our old joints need all the help they can get to remain healthy and allow you to turn and turn and turn those pedals.

Go too tall and you'll be uncomfortable when you straddle and may be stretched out too far. Go too short and you won't be able to get the handlebars up high enough without solutions that might be ugly on such a small bike, or even detrimental.

Road Fan

this I agree with completely!

Road Fan

Stapfam, there IS such a thing as too much standover height! If you've ever felt the resulting pain in the hard AND SOFT parts of your undercarriage, you'll know why.

oilman_15106

Free bike fitting advice is exactly what it is worth.

Got to a good LBS and talk to them about it. Almost every bike company's frame will fit you differently. At 5'7", I have road bikes that range between 49cm and 54cm "size" and they all work for me but I got an expensive education on the bike fit thing. As an example a 54cm Colnago frame would be way too big for me but a 54cm Titus road frame is not.