Bikes for the Very Tall



Intent

At 6’7” or 200cm, I’ve spent a lot of time riding bikes that don’t fit me. For years I bought whatever XL bike a bike shop had in stock that was on sale for a few hundred. As I become more and more interested in cycling, particularly mountain biking, I begin to realize that a “extra large” can mean wildly different things from company to company, bike to bike. Some XL bikes are suitable for someone my size, and some would be a cramped fit for someone 6 inches shorter than me.

When I made the decision to invest in a full suspension mountain bike I realized that I would need to do a lot of research that would fit me well. As many forum commentators are fond of saying, there no deal is a good deal on a bike that doesn’t fit you.

If you’re reading you may be accustomed to all your sleeves ending halfway down your forearms and you may have resigned yourself to driving with your knees hugging the steering wheel, but I hope you’ll think seriously about getting the right size bike for you. A badly fitted bike is much more irritating and potentially unhealthy than any other “tall person problem” I’ve encountered.

Background

In the early days of buying bikes I always made my decisions based on the seat post length. In America, finding a bike with a 21 inch sticker on the seat post meant that was the big bike, and your search could end. After I started to look at geometry numbers though I realized that this was almost completely uncorrelated with the size of a bike. I realized I needed more information to make a good decision.

After spending way too much time pouring through geometry charts, this is what I’ve come up with:

Important Geometry Numbers

In my opinion, the three most important numbers for determining whether a bike will fit you are:

  • Pythag BB -> HT
  • Angle of BB -> HT
  • Effective Top Tube

Almost all the information you need about a bike can be derived from these three numbers.

Obviously the second two are not numbers you can find in any geometry chart. I’ve made them up, and I’d love it if someone could suggest better names. But what are they?

Pythag BB -> HT

This is the point to point distance from the center of the bottom bracket to the top center of the head tube. It is found with a simple application of the pythagorian theorem used on the Stack and the Reach. This is possible because Stack and Reach are always perpendicular.

Pythag BB -> HT = sqrt( stack^2 + reach^2)

In my opinion, this number is the single most effective way to compare the relative size of a collection of bicycles. By merging the Stack and Reach it gives on one number… essentially how far your hands will be from your feet.

Angle of BB -> HT, now known as Chill Factor

Obviously, there are many different styles of geometry. Modern endurance road bikes advertise their upright riding position which can make a long ride more comfortable, and modern mountain bikes are all about getting “long and low”. To be able to tell where a bike falls along this spectrum, I measure the angle between a flat line projecting forward from the bottom bracket and the Pythag BB -> HT line and call this, rather brilliantly, “Angle of BB -> HT”. Hobocross over at Bike Counterculture came up with a better name though: Chill Factor!

Chill Factor = ARCTAN( stack / reach ) in degrees

The larger this number the more comfortable a bike’s fit should be, all other things being equal. For example, the comfort oriented Fargo has an angle of 59 degrees, while XC racer SC Tallboy has an angle of 51 degrees.

Effective Top Tube

Last, and perhaps least, is the Effective Top Tube. This is the number many if not most major bike companies use to advertise and discuss size these days. It is the horizontal distance from the center-top of the head tube rearward to the point in space where the seat post would intersect said line, presuming the seat post is extended that high.

This number makes a lot of sense in theory, but there are a few problems with it:

  • If your legs are particularly long or short for your size, your seat will be spaced closer or further from the head tube than ETT suggests.
  • Fore-aft seat position should ideally be dictated by getting your knees in the right position for ergonomically sound pedaling. This gets more complicated with mountain biking, but it is still a major factor.
  • On mountain bikes, actual seat post angles can depart radically from the “virtual” seat post angle suggested by the line from BB to ETT. Having the seat higher than the ETT line causes it to more rapidly depart from the ETT length.

Effective Top Tube essentially fits you to a bike based on your torso length while completely disregarding your legs. Buyer beware.

Conclusions

Between these three numbers, you’ll be able to have a decent idea of the size of a bike. Ideally you’d test ride anything before you even considered that, but that is easier said than done when ordering a rare bike in a rare size. If you can compare the numbers I’ve laid out to bikes you have ridden, you’ll at least have a reference point.

I also must point out that you shouldn’t get so caught up in getting the best fitting bike that you forget what sort of bike you want. If a 160mm travel Enduro bike is your perfect size but you’re mostly riding gravel roads, there is no way it will be better for you than something a centimeter off here or there, but with the right travel for your purposes.

Link to Document

So without further ado, here is the list.

Bikes for the Very Tall.

You should be able to sort it however you want, but by default it is sorted by Pythag BB -> HT. I keep it hosted on Google Sheets so it is easy to share, update, and modify. Feel free to download a copy for yourself or ask me to add a bike.

Possible Ways to Improve

There are many ways I could improve this database, but I don’t know what would be helpful for most people. If you have ideas let me know.

One problem I’ve been thinking about lately is the phenomena of short chainstays on mountain bikes. Having a shorter wheelbase is nice for switchbacks, but it seems ridiculous that rear triangles are not size-specific. Giving everyone a 415mm chainstay means that a shorter man or women has a massively easier time keeping their front wheel grounded and stable when climbing. Conversely, my saddle begins to drift over my rear axle at the slightest hint of an upward slope. I’m thinking about calling this the Unicycle Problem: as one’s height increases a bicycle begins to behave more and more like a unicycle that you’re perched atop.

For mountain biking, it would be incredible to have a way to calculate your downhill seated angle to tip-over and your uphill seated angle to tip-over,. This would essentially be a measure of how “in” versus “on” the bike you are, both uphill and downhill. I’ve been wracking my brain, but I have yet to determine a formulaic way to compute this given the complexities of center of weight and the ambiguous design of modern seat posts. This raises the intriguing question of whether the enhanced ability of tall people to shift their center of weight around more balances out the lower center of gravity of short people. That is a question for another day perhaps.

tall, bikes, bicycles, cycles, 6’4” 6’5” 6’6” 6’7” 6’8” 6’9”, xl, xxl xxxl, 2xl, 3xl

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