What's a Compact Crank, anyway?

[Bad JuJu]

Will someone please explain to me what a "compact crank" is and why they're so popular?

I know what "compact" means, and I know what a "crank" is--yes, on the bike as well as in other areas of life . But put them together and all I can do is display my ignorance. Please enlighten me. Thanks!

Because I know you can't all be talking about some short guy who's hard to get along with.

[caligurl]

it's something between a triple and a standard double....

if this were a testosterone forum... i'd stir the pot and say they are too weak for a straight double and too egotistical to admit they need a triple....

however... they have a purpose!

if you need easier gearing... but don't have the hills... then a compact is a good compromise (i see you are in florida... so you are probably a good candidate for a compact!)

by the way.... i had a triple put on my ruby cuz i like to climb gruesome hills!

[DebW]

It's a wide-gap double. Think granny gear for inside chainring.

[Adventure Girl]

A triple might be something like 52/39/30.
A double might be something like 53/39.

A compact double is a double that has a smaller big ring and a larger small ring. Something like 50/34.

You don't get a big big ring. But you get a smaller small ring than a conventional double.

[caligurl]

It's a wide-gap double. Think granny gear for inside chainring.

oh... that's good! except it's not quite granny easy... nor is the big ring a "regular" big ring hard... both are in the middle... OR.... if you choose one or the other to be the same size as a standard big ring or standard granny... you will lose gears on the other ring!

that's why i didn't get a compact... i wanted my easiest gears... but i would have lost my harder gears... and i'm often out of gears when descending a hill already! didn't need to lose more!

[mimitabby]

but why are we calling a chainring or gears a crank? I am confused.

[DebW]

but why are we calling a chainring or gears a crank? I am confused.

A crank consists of chainrings, spider, and pedal arms. Because you need different spider arms with a different bolt circle diameter for a triple, double, or compact double, the chainrings aren't interchangeable. And the right pedal arm attaches to the spider. So you need the whole shooting match to switch from one to the other, ie, you have to replace the crank.

[mimitabby]

so the gizmo that the pedal sits on is NOT a crank, it's a pedal arm?

[Fredwina]

(i see you are in florida... so you are probably a good candidate for a compact!)

That depends. I spent a year in Tallahassee. I can remember a hill or two in Leon county that I was glad to have a triple. The Panhandle (JuJu, I know "Tally" really insn't consdered the panhandle) can get hilly, as in short but steep.

[Bad JuJu]

Wow, thanks everyone--this has been hugely enlightening. The reason I asked the question is that I'm getting my Bianchi Veloce soon, and it's a 2005, which has a triple. But someone said the 2006 has a compact crank, so I wondered whether I was getting a bad deal, even though the price on the 05 Veloce is the deal of the century.

But now that I know what a compact crank is, I'm glad I'm getting the triple. While this area is free of actual mountains, there are some hills that have you reaching for your granny gears, as Fredwina noted. Also, I do ride in other areas occasionally, and I'm not too proud to go for the grannies when I need them.

[mimitabby]

when are you getting your bike Bad JUJU?

[DebW]

so the gizmo that the pedal sits on is NOT a crank, it's a pedal arm?

You can say that the pedals are attached to the crank, because the pedal arm is part of the crank. The arm, spider, and chainrings go on and off the bike in one unit, collectively called "the crank".

[mimitabby]

You can say that the pedals are attached to the crank, because the pedal arm is part of the crank. The arm, spider, and chainrings go on and off the bike in one unit, collectively called "the crank".

Thank you Deb, you are making sense to me. So what about a short crank?
there was a thread just a little while ago about a short woman wanting a short crank. for that matter, the average woman IS shorter, should women's bikes have shorter cranks, and is that a big problem?
(Do they sell them?)

[DebW]

Thank you Deb, you are making sense to me. So what about a short crank?
there was a thread just a little while ago about a short woman wanting a short crank. for that matter, the average woman IS shorter, should women's bikes have shorter cranks, and is that a big problem?
(Do they sell them?)

You are full of questions today, Mimi. I suppose I should add that a crankset includes the left crank arm as well. A short crank means that the arms are short, sized to match a smaller person's leg length. Crank arms come in 165, 170, and 175 mm and maybe some in-between lengths. So yes, a well-designed woman's bike would have 165 mm arms matched with smaller frame sizes, 170 mm arms for larger sizes. A good fitter would determine the proper crank arm length independent of frame size. Crank arm length has nothing to do with the chainring size or gearing per se, but of course a longer crank arm gives you more leverage for turning over a bigger gear.

[Bad JuJu]

when are you getting your bike Bad JUJU?

Thanks for asking, Mimi! I get paid tomorrow, so possibly next week. *drooling at the thought*

Don't worry, TE forums and the other TE Bianchi girls will be among the first to know!