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September 19, 2011

Compact Crank: You Want One #roadcycling


Earlier this year I finally had Atlanta Cycling put a compact crank on my road bike. I'm here to tell you about it. If you know all about bicycles and cranks and stuff, this article isn't for you. This is for those who are wondering if they should change out their standard for a compact crank. If you are wondering this as you struggle climbing hills, then you could just stop reading now and go ahead change your crank. I can say with confidence that you should. Read on if you want to understand what this is all about.

Note that I'm assuming that you don't already have a three-ring crank. If you have a three-ring crank, the only thing a compact crank might do for you is save a very small amount of weight. It will not make it easier to get up hills because a compact crank's smallest ring is going to be larger than your triple's smallest ring. Stick with what you have.

Background

The crank-set is the two or three rings with teeth connected to the crank arms. The crank arms are connected to the pedals. The pedals are connected to the cleats. The cleats are connected to the shoes. The shoes are connected to the foot bone. The foot bone's connected to the...

Anyway, a regular crank typically has 39 teeth on one ring and about 52 teeth on the other. A compact crank typically has 34 and 48, or maybe a couple more. The lower number of teeth in the compact crank-set allows you to spin faster in your lowest gear, making it easier to get up hills.

Notice that I didn't say easy. I said easier. Don't set your expectations too high or you'll be disappointed. A compact crank will not make a hard hill easy. But it can help you make it up the hill without having to mash as hard.

As an aside, developing a fast cadence is good. 'Fast' is, say, faster than 90 RPM. A compact crank isn't going to help you have 90 RPM up a steep hill. I'm just saying that a fast cadence everywhere else is better for your knees and muscles (it's easier n them). It's also better for your heart and lungs (gives them a better workout, which they could probably use). Your heart and lungs can recover more quickly and take punishment for longer periods. There are other benefits to a fast cadence such as the ability to respond and accelerate more quickly. Coach Levi wrote a nice article on this topic.

The Verdict

I like my new crank. As I said above, if you are thinking you might want a compact crank but you are just not sure, just be sure. I'm sure; you want one. I can get to the top now with less fatigue. Not "no fatigue"; less fatigue. If you don't ride much, you might not even notice how much easier it is. I ride the same hills every week and have done so for 4 years or so. That's enough riding that I can notice the difference. If you ride some big hill only once per month, you might not notice the benefit of the compact crank, but it's there.

I also enjoy the 3-gaps North Georgia mountain route much better with a compact crank.

Concerns Debunked

Some people say that a compact crank will make you run out of gear and cut your top-end speed. Eh, well, maybe. They note that you'll "spin-out". Spin-out isn't wiping out, thankfully. Spin-out is when you can't or don't want to pedal any faster. With the compact, I spin-out north of 37 MPH (though I don't remember when I ran out of gear with the standard -- sorry). And I can still coast down hill at 40 miles per hour on my rides. That's fast enough for me. Besides, I'd just as soon coast down hill to rest up for the next climb. I don't need any more top-end. I'd rather enjoy the easier up-hills than the faster down-hills.

Another concern you might have is that you'll run out of gear on the small chain ring and that you'll therefore need to spend more time in the big chain ring. You may be concerned about having to do more shifting. Well, I guess this is true. I do spend more time in the big chain ring. And I do change gears using the front derailleur more often. However, it's not quite as much as you might think. Besides, with the compact crank I can start off from a standstill in the big chain ring as long as I'm not pointing up hill. You need to get good at shifting anyway and if your bike doesn't shift well, fix it.

If you are young, strong and getting stronger, a compact crank may make you slower and cause you to plateau. If you find a mountain climb strenuous, but you can do it and enjoy it in a standard crank, then keep using the standard. It will make you stronger. But if you are young, strong, and getting stronger, then this article probably isn't for you anyway.

Cadence

I wasn't expecting to have a faster average cadence with the compact, but it looks like I do. I was expecting my cadence on most of the route to be the same, with a faster cadence only on the worst hills. I thought the time spent in the lowest gear would be short enough to not impact the average over the length of the ride.

My average cadence on my regular ride used to be 84 to 88. Now it's 87 to 90. Nice. But I do not think it has impacted my pace.

Here's an example with the regular crank: http://connect.garmin.com/activity/29757090

Here's a comparable example with the compact: http://connect.garmin.com/activity/72575356

Same pace, same time of year (winter), faster cadence.

My Dunwoody Cycling group does a faster pace in the summer and fall. My otherwise comparable rides with the regular crank have a lower cadence: http://connect.garmin.com/activity/55940780

But I'm Not Mechanical

I'm quite mechanical and am confident that I could have figured out what to buy and how to change out the crank-set. But I'm not really interested in bicycle maintenance these days. Too many other time demands. If you enjoy bicycle maintenance, then you probably know whether you could do this yourself. If you are unsure, then take it to a bicycle shop. That's what I did and don't regret it.

What's it cost?

I paid less than $350 (January 2011) for a new compact chain ring and crank arms and new shifter cable guides, including labor. It would have been more like $500 if I went with a Shimano Ultrega crank-set, but I went the cheaper route. There are certainly lots of variables, so your cost could be much different.

Recommendation

Just do it. If you switch (or have switched) to a compact crank, share your experience in the comments.

1 comment:

  1. Darrell Farlow says: I ride with both Compact and Standard, but a Compact (50/34) running a 11x25 cassette has suprisingly similar low end granny gear ratio as a Standard (53/39) running a 12/28 cassette. And SRAM Apex (maybe others) offers a 32 tooth cassette that would come close to replicating the low end options of a triple crank.

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