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Discussion Starter · #1 ·
Hello everyone. I recently began biking for fitness. I currently ride a hard tail mountain bike, but it doesn't fit me right and I want to purchase something new. Considering I only ride in the street and on paved paths with the very rare flat dirt crossover, I have decided to purchase a road bike. I've read plenty of guides online, including here, and I understand the importance of a proper fit. However I am confused about buying the right size.
I used this site: Road Bike Size Calculator to determine that I need a 60mm frame. However I will be buying online and am afraid of ending up with something that is too big. Im wondering if I can buy something slightly smaller and compensate by adjusting the seat post if necessary. Is there a lot more to the size than the length from my seat to the pedal?

If it helps I am 6ft tall and measured 35 inches from the floor to the top of my inner thigh. I know the best route would be to buy a bike in a shop. Unfortunately road bikes at my closest shops start in the $800 range which is a lot more than I am willing to invest for the amount of time I will be using it. Any input would be appreciated.
 

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Is there a lot more to the size than the length from my seat to the pedal?
Yes, there is. You have to consider the distance from the saddle to the handlebar ("reach") and the difference between saddle height and handlebar height ("bar drop"). Even if you can adjust the length from the seat to the pedal ("saddle height") just fine, you'd be facing an unsolvable reach problem and bar drop problem if the frame is much too large or much too small for you. I'll leave the details for others to explain.

On your numbers: a 60 cm (not mm) frame seems too large for a 6-footer. But with bike companies being wildly inconsistent with their sizing schemes and people having different proportions, I suppose it could be a good number. Still, I would re-check my numbers and perhaps have someone else do the measuring and calculations.
 

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Discussion Starter · #3 ·
Thanks for the input. Ill measure my legs again with some help and see if I get the same result. If I do I might just order a 56-58cm just to be safe. I think if I had the option its better to have bar thats too close vs a bar thats too far. I know its not as simple as all that but as long as its comfortable I should be able to ride it.
 

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I think if I had the option its better to have bar thats too close vs a bar thats too far.
Most people who are coming into the sport think that. They loathe the notion of being "too stretched out." But in reality, it's much better to have your back stretched a bit than have it arched. In most cases, what feels "too stretched out" when first getting on a bike will turn out just right after some miles of spirited riding. I can't caution enough against buying a road bike and setting it up so you can sit on it like you would on a beach cruiser. People do all the time, and they'll never be comfortable.
 

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Discussion Starter · #5 ·
More good info. Thank you. I think I might go to my shop and see if I can pay them to size me properly. They're really nice, helpful guys and I don't want to pretend to be shopping just to screw them over.

I can see how the arching could definitely be a problem. My MTB is way too small for me. I compensate by standing a lot, but after a good 20-30 mile ride I definitely feel some back aches. I wouldn't think that a bike that's 1-2 cm too small would be as bad, but if Ill try to get it as close to perfect as possible
 

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I am 6ft tall and measured 35 inches from the floor to the top of my inner thigh. I know the best route would be to buy a bike in a shop. Unfortunately road bikes at my closest shops start in the $800 range which is a lot more than I am willing to invest for the amount of time I will be using it. Any input would be appreciated.
It's not clear you've measured your inseam correctly. To measure your inseam: stand against a wall with your feet 6 inches/15 cm apart, no shoes. Push the spine of a 1 inch/2-3 cm thick book into your crotch with significant pressure, and measure the distance from the book spine to the floor.

Here are several frame fit calculators.

Bike Fit Fitting A Bicycle Seat Adjustment Height Reach Tips by Jim Langley
The Colorado Cyclist :: Bicycle Parts and Accessories
to frames/index.html
Lugged Steel Bicycles, Wool Clothing, Leather Saddles & Canvas Bike Bags from Rivendell Bicycle Works /Articles.asp?ID=247
How to Fit a Bicycle

Your measurements are quite close to mine (pending a corrected bicycle inseam number) and I ride a 59 cm traditional frame (horizontal top tube) with a 57.5 cm top tube (center to center).
 

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I think I might go to my shop and see if I can pay them to size me properly. They're really nice, helpful guys and I don't want to pretend to be shopping just to screw them over.
You just gave yourself some great advice. Take $50-$75 of your bike budget and use it on a standard fitting. It'll get you the info you need to compare the geo of the test bike to the geo of online offerings and buy the correct size online. Going this route might just save you some money in the long run, and will certainly better your odds of success.

Also, kudos to you for being upfront with the LBS's. Don't be afraid to discuss your intentions with the fitter, because tapping them as a resource after the fitting (ex: to help you pick an online bike with geo that suites you) would be a big plus.

I can see how the arching could definitely be a problem. My MTB is way too small for me. I compensate by standing a lot, but after a good 20-30 mile ride I definitely feel some back aches. I wouldn't think that a bike that's 1-2 cm too small would be as bad, but if Ill try to get it as close to perfect as possible.
An ill fitting bike is an ill fitting bike, and will likely lead to discomfort which leads to poor performance. Too small versus too large just sets the stage for different types of fit issues, but both are bad. Aim for right. A lower budget shouldn't mean that you have to settle for less than a good fitting bike.
 
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