Buying a bike online, and by yourself is hard. That’s why I run through my process for sizing, and compare it to 3 popular online size calculators to find out the best frame for my new bike.
Back to basics. I’m about to buy a new bike, and because of my location, I’m going to buy it online. Don’t hate on me, but I shit you not, there are no bike shops where I live. NONE!
Saying that though, this is not the first time I’ve had to order a bike online, so I’m going to cover common pitfalls. Then, once I have the bike, I’ll look more closely at biomechanics and fine tuning the fit DIY style.
What’s Your Biggest Concern When Buying Online?
Returns, warranty, service? The first thing that I think about is size. Like with clothes and shoes, I have bought the wrong size before, which is funny because it reduces the savings made unless you’re in the USA and you have Zappo’s!
I Got My Size Wrong!
Straight up let me say, I’ve got my sizing wrong in the past. All the way from Taiwan to Australia. Ouch! Lucky for me, I was sent two frames by accident. Here’s what I’m doing differently this time, and hopefully you can learn from my mistakes.
The crazy thing is I know my bikes sizes. Like who doesn’t right? If you have a bike now, just go measure it and order the same frame. HA! I thought cause ride a 56 cm on the road and 17”/18” off-road, it couldn’t be easier.
So how did I get it wrong? Three words – Head Tube Length. Plus the old roadie favourite, slamming the stem. We’ll get to that in a moment though. First I want to touch a little on bike measurements.
What Bike Measurements Really Count?
Here a little story on the history of bike frames. Long long ago, up to the late 90s, almost all bikes had a horizontal top tube due to manufacturing constraints (lugged frames using lugs with fixed angles) they tended to have a certain proportion between frame “height” and “length” in order to fit the average rider with a certain height. Less flexibility in production techniques meant standardisation amongst frames.
Today is a different story though. Don’t quote me, but I would say ever since Giant started making bikes for ONCE in the late 90s, shit started to change. Giant introduced the compact frame, and the standard top tube measurement was lost forever. In addition to this, carbon moulding has got more advanced, brands are now able to hydroform aluminium into gnarly shapes etc etc. So not has standardisation in frames gone, so has the ability to adapt to the variations in leg-torso proportion for people with the same height.
It’s safer not to consider the relation between length/height of two frames to have a correspondent variation of the other measure. In other words, it’s perfectly plausible to have two frames with same seat tube length and significantly different effective top tube length, and vice versa.
How Do I Get Measure the Right Size Bike?
Effective top tube length is key. The most important measurement is not the seat tube, but the effective top-tube. If you have a bike that works for you, measure the effective top tube length. Having this number allows you to compare frames from different manufacturers and bikes built for different purposes. This is done by measuring from the center of the head tube; horizontally back to the center of the seat post.
People talk about stand over height. It’s a little overrated in today’s bike world. Yes, it plays a factor in standing over your bike, but use effective top tube as your first point of reference then make your way down the hierarchy to stand over height.
This week I’m going to first decide what bike is my ideal size based on my experience, then test this out with 3 online bike fit calculators.
Different bikes mean different frame measurements and geometry. This is where it starts to get tricky. My first step is looking at past bikes and comparing their frame measurements and geometry to each other. For me, my good old Scott CR1 from 2007 was a bike straight off the shelf that I didn’t have to make any changes to. It just worked.
So it’s my baseline for a good fitting bike. In the comparison is another bike, a Velocite Magnus. I’m not sure if you know about this company but they are predominantly making international sales through their online store. So this is the bike that I had troubles fitting into. Another good comparison in the other direction.
The bike I am considering is the Canyon Ultimate AL. It’s an online brand is the only bike company that will ship directly to me.
Canyon Ultimate AL
Sizing Comparison Charts
|Scott CR1 (L)||Canyon (M)||Difference|
|Magnus (M)||Canyon (M)||Difference|
|Scott CR1 (L)||Canyon (L)||Difference|
There a couple of things worth pointing out here. Namely, the reach, which includes the effective top-tube length and the stem added together, and the headtube length. I mentioned this at the start of the show because I got it totally wrong. If you check the difference between the Scott and the Velocite, it’s a whopping 25 mm. That may not seem a lot, but I’ll tell you, I felt it from my first ride, and regretted slamming the stem without checking first on every single ride on that bike! Ouchy wah wah.
So there you have it. I looked at the M and the L and can’t go past the M. Style wise, riding a little smaller is always going to work out cooler. But seriously, because the angles and measurements didn’t match, I choose the smaller of the two options. A couple of other loose ends. Handlebar size based on my shoulders is 42cm, and I will choose 172.5 cranks and work out later if they are they best for me biomechanically.
Which Online Bike Calculator?
Now that I’ve made my decision on previous experience. I decided to put the one size fits all online calculators to the test. I am going to go through the best online measurement tool. This is what I did. I got my size then I went and matched it to the results.
These are the standard measurements I used for all 3.
Shoulder Width: 41.5cm
Arm Length: 67.5cm
Lower Leg: 55
Sternal Notch: 146.5
The Competitive Fit (cm)
Seat tube range c-c: 54.1 – 54.6
Seat tube range c-t: 55.7 – 56.2 (54.5) 1.2 – 1.7 smaller
Top tube length: 53.1 – 53.5 (54.9) 1.8 – 1.4 larger
Stem Length: 11.2 – 11.8
BB-Saddle Position: 71.5 – 73.5
Saddle-Handlebar: 52.3 – 52.9
Saddle Setback: 6.1 – 6.5
This brings up a good point. I’m a racer, well currently I just like to think I’m a racer. Along the way people must make decisions on things like bar height, etc. I am still drawn to looking good rather than ultimate comfort. So keep this in mind when you decide whether to use this information for yourself.
The Eddy Fit (cm)
Seat tube range c-c: 55.3 – 55.8
Seat tube range c-t: 56.9 – 57.4 (54.5) 2.4 – 2.9 smaller
Top tube length: 53.1 – 53.5 (54.9) 1.8 – 1.4 larger
Stem Length: 10.1 – 10.7
BB-Saddle Position: 70.7 – 72.7
Saddle-Handlebar: 53.1 – 53.7
Saddle Setback: 7.3 – 7.7
The French Fit (cm)
Seat tube range c-c: 57.0 – 57.5
Seat tube range c-t: 58.6 – 59.1 (54.5) 4.1 – 4.4 smaller
Top tube length: 54.3 – 54.7 (54.9) 0.6 – 0.2 larger
Stem Length: 10.3 – 10.9
BB-Saddle Position: 69.0 – 71.0
Saddle-Handlebar: 54.8 – 55.4
Saddle Setback: 6.8 – 7.2
WS Recommended Road Sizes
Frame Size center-to-center:
54 cm (54.9) 0.9 larger
Frame Size center-to-top:
56 cm (54.5) 1.5 smaller
69.25 cm (67) 2 larger
73.73 cm (74)
42 cm (same)
My vote is Wrench Science as the most accurate.
A Note on Bike Fit Calculators
While the demonstrations on how to do all of the measurements are quite detailed, exact measuring points may not always be straightforward. When I first used the calculator, for example, I found myself adding a few extra cm to the arm length measurement as I was not sure exactly where my pivot point between shoulder and arm was. And, as should be obvious, if the measurements aren’t entered inaccurately, then the fit the calculator spits out will be of little use.
Tech, Hacks & Products Section
Do you know about packing surgical gloves in with your spares? If you don’t here’s the low down. With white bartape being more prevalent, and the semi-pro having to fix all their own flats, no wheel changes here, surgical gloves will save you from getting dirty hands on the change. Having dirty hands is almost like having a sharkbite on your calf. Almost, but we both know anyone with a sharkbite is a total noob.
So pack some surgical gloves and thank me later.