The Short Crank

I’m tall.  Six feet and three inches tall.  And a disproportionate amount of that is in my legs.  I had a hard time fitting into a velomobile.  When I went for a test drive at Bluevelo, they did every trick they could think of in order to squeeze me into one of their machines – and I still skinned my knees on the inside of the Quest’s body!  If I was going to become a velonaut, it was going to require extreme measures.  As I started considering the benefits of orthopedic surgery, Ray came to my rescue with a way to gain a few more precious millimeters: shorter crank arms – 155 mm instead of my normal 175 mm length.

Now I’ve been bicycling all my life and the mantra of “if it’s not upright, it’s not a bike”, “if your not wearing Lycra, your not a biker”, “lighter means faster”, and “longer legs, longer cranks” were firmly wedged into my tiny neanderthal skull.  But I was already making a huge leap of faith going directly from upright racer to velomobile!  I didn’t even bother with the obligatory evolutionary steps through the domain of open recumbents first.  So if this neanderthal was going to sail straight off the edge of a flat earth in his low, heavy bike wearing cargo shorts, he might as well do it with short crank arms.

Well I ordered my short cranked Strada and waited.  And worried.  When it finally came, I made the seat and bottom bracket adjustments with trembling hands and exhaled a huge sigh of relief when I slid into the seat.  My knees didn’t rub.  Disaster averted!  I put on my cargo shorts, gave my short cranks a push, and over the edge I went.

I’m now nearing my eighth month of velomobile bliss.  My upright bicycle muscles have become recumbent and all of the promised gains of speed and energy economy have been realized.  The shorter cranks don’t seem to have had any negative effect at all!  But the real surprise for me was the fact that uphills seem easier for me now!  Sure, they’re a little slower but they aren’t the energy drains that they used to be.

The Strada is 3 1/2 times heavier than my road bike was and going up steep hills at slow speeds robs the velomobile of every advantage.  Yet it still seems easier.  How can that be?!  Part of it, I’m sure, is that the upper body is taken completely out of the equation.  No more stress to keep the body from inefficient movement, no more rigid arms and shoulders or pulsating pulls on the handlebars – just keep the feet going around.  But I’m convinced it’s more than that…

I used to be a fencer – the kind with a sword, not a shovel – and we did a lot of squats and lunges for that sport.  I can tell you that I could do half squats or half lunges all day long but don’t ask me to do too many full squats or lunges in a row or I’ll be falling over pretty quickly.  The point is that it takes a lot less effort to push the same weight (me) if the legs don’t bend as deeply – the same reason hikers take smaller steps as the mountain becomes steep.  In the same way, the shorter crank is allowing me to take ‘shorter steps’ because my legs don’t have to bend as deeply to do the same amount of work.  Also, the short cranks don’t seem to offer any disadvantages when they aren’t climbing.  In fact, I’ve come to believe that the shorter cranks may allow me to do the same work, with the same muscles, with less energy, all the time – but especially up hills, where the resistance is greatest.

Perhaps I am taking an unrealistic leap of reason in this – especially since too many variables were changed in my little experiment – but I think I can safely conclude, at the very least, that the short crank shouldn’t be feared.

6 thoughts on “The Short Crank

  1. Nicely written! You should consider becoming a professional writer 😉
    At this moment I’m riding a 170mm crankset but I’m also considering changing it to a 155 or 160. I’m a little bit a afraid to make to big of a change. The big change will happen this winter as my chainrings are almost worn-out. I’ll change my 30-42-52 combination for a 46-56 combination with ovalized chainrings. The granny-ring 30 has never been used. During the winter period my legs will have time to adapt to the new set-up. Your story gives me the confidence that changing to a smaller size crankset doesn’t mean a decrease in speed.

    • Thanks for your very kind words. I hope you get the same results from short cranks and can’t wait to hear your impressions of the oval rings. But you could never get granny away from me – she’s saved me on many a steep and sweaty climb. Well, maybe a few ‘not so steep’ ones as well…

      All the best to you Robert-Jan!

      • There was an article about shorter cranks in the magazine of the Dutch recumbent “Ligfiets &” wich pretty much concluded the same things you do, especially in how the (time)lenght of mucle contraction being more optimal that way and knees are less strained because they do not bend as much as you explained

        Only ”downside” is that because the rotation you make is smaller and the power needed to rotate the cranks would be higher, you will need to ride in one or two gears lower/lighter, probably increasing your average rpm as you go along. Wich is also not a bad thing at all.

        I think you did above naturally as you experienced pedalling much lighter then you used to with other bicycles. Robert-Jan will probably have to adapt to the new situation riding the same velomobile where you did right away when getting used to riding a velomobile in the first place ;-))

  2. You’re absolutely right – I changed so many things that it felt like starting all over again. You make an excellent point about the short cranks requiring higher rpm and lower gear. I hope that Robert-Jan reads this before he gets rid of granny – he may need her after all… Thanks for adding your insights again Arjan!

    • I have absolutely no intentions keeping the granny-ring. As you may know I live in The Netherlands near the coast. I use my Quest 99% for commuting. On the 60 kilometers single way between Leiden en Utrecht there is only 1 big bridge which I can climb using 52-24 doing approximately 24 km/h. Furthermore I have no intentions taking my Quest to the mountains. I already did 28.000 km in 2 years and I have absolutely never used the 30 tooth chainring. Last year I had a 32-11 cassette in the back which I changed for a 28-11 this year and there wasn’t a moment I missed the 32, not even when accelerating at traffic lights. So thanks for worrying, I appreciate it. I still think a 160mm. crankset with a 56-46 chainring set-up won’t be a problem. What if in the end I am wrong??? Than I’ve made an expensive mistake 😉

  3. Great thoughts on the shorter cranks. I used the shorter cranks on my XS and found the same as you did. I live in an area of Canada that is flat like the Netherlands. But I do use the 30 chain ring quite a bit in the winter with the studded snow tires, but otherwise it sees no use like Robert-Jan. An interesting note is your heart rate is lower on a recumbent than an upright bike also. But I guess a high heart rate is better than no heart rate.

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