Buying A Compact Crank

kensek

I posted a thread several weeks ago because I was unsure if I wanted to get a new bike or just change the crank. After reading the latest bicycling magazine I have decided to keep my bike and get a double crankset. I think it will just be easier to maintain and promote better shifting. I don't know if I should get a standard double or a compact crankset. I know a compact double is prefered by many but can I also get a standard double? Which would be better? My bike has Shimano parts (Tiagra/105). I would like to keep this upgrade under $75 and I don't want to change any of the other parts if possible.

gclark8

What crank do you have on the bike now?

Edit: Found it: http://www.cyclingforums.com/t450317.html

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Peter@vecchios

You can put a double ring crank onto your bike w/o any other changes, even if you have triple derailleurs, BUT gearing and needed ratios is a personal choice. Either a standard or compact will work but the resulting gearing nobody can spec for you.

alfeng

Yes, you can also get a standard (130BCD) road crank ...

Since you mentioned (in an earlier thread) that you "ride on mostly flat terrain" you really don't need a "compact" crank ... but, that doesn't meant that you shouldn't avoid one, either ...

For cosmetic reasons, since you've currently got a triple -- and, because 'I' recommend the triple front derailleur & triple rear derailleur (with more chain capacity) when using a compact crank -- you may as well get a compact crank so it looks like an intentional setup!

For practical reasons, it is nice to have a wider range of gears even if you are currently only riding on flat terrain ... at some point in the future, you may move to an area which has hills OR your rides may become longer (this does not apply to people who live in truly FLAT places like Florida) and take you to places that have hills, so a compact is often a better choice for non-competitive riders.

If you factor in what you might get by re-selling the triple crank + BB on eBay, then that will give you a little more flexibility in your crank & BB choice ... so, your $75 can actually be closer to $100+ (you'll probably get more than $25 -- the extra money will pay for the installation tools), but you can certainly get a compact crank & BB for closer to $75 if you are a wise shopper.

There ARE reasons to get/use a standard crank ... the practical reason is that 130BCD (the current ROAD standard) chainrings are readily available in all tooth counts & price ranges. 135BCD (Campagnolo) & 110BCD ("compact") chainrings are not as readily available, and consequently you normally have to pay more for replacements.

The other reason to choose a standard crank is because the shifting is generally a little better BECAUSE the difference between the chainrings is smaller AND (in the past) the crank & rings were stiffer ...

Cranks, chainrings & front derailleurs are generally MUCH better than in the distant past ...

So, while a standard crank would be slightly better, Since you will probably be leaving the chain on the large ring most of the time, the slightly better shifting that a standard crank usually has probably wouldn't be missed if you got a compact crankset.

BTW. Just for your reference, a bazillion years ago, the so-called "compact" crank was pejoratively-or-euphemistically (depending on who was saying it & to whom) referred as a crank with "Alpine gearing" ... but, the compact crank only became fashionable a few years ago AFTER Pinarello introduced one of their bikes with the Pinarello name stenciled on a compact crankset (thus, a literal imprimatur) & Tyler Hamilton won a Stage of the Tour de France using a compact crankset. Consequently, the stigma of having a compact crank no longer exists.

kdelong

just getting post above spam

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daveryanwyoming

And 11 and 12 tooth cogs became widely available so you didn't have to sacrifice top end gearing to go compact, compacts weren't too popular back when 13 tooth small cogs were commonplace...

lava

Wait a minute - am I reading that right? I can buy an Ultegra compact double and it will work with my Ultegra 6500 triple setup? That is great news...

Do I have to swap bottom brackets to do that, even if I currently have an Ultegra BB?

Peter@vecchios

Ders don't really care, particularly the rear. As for BBs, the shimano compact is the outside bearing, 2 piece affair from. If you have a spline/Octalink type, you need a new BB. Lower FD, check chainlength, adjust FD, go ride.

alfeng

Yes, but your Ultegra 6503 crank is probably mounted on a 118mm BB ... so, even if you were to get a RITCHEY or STELLA AZZURRA "compact" crankset (there may be others; and now, I'm not sure if SA even made a compact crank) which uses an Octalink BB, you'd probably want a BB with a shorter spindle -- typically, 109.5mm -- though it wouldn't be necessary.

If you don't immediately need/want a "compact" crank, you can just get a 109.5mm Octalink bottom bracket, remove the granny, re-mount, adjust the front derailleur stops ...

FWIW. I have gravitated toward using 112.5 XTR Bottom Brackets with the various Shimano Octalink ROAD cranks as often as not ... with that length, I can use either a double or triple crank without changing the BB.

Also, this should not be applicable to your GIANT OCR2 ... however (for the benefit of others who may have different frames & contemplating a similar conversion), on ONE bike which has an alloy frame (135mm rear spacing), I chose a 118mm ISIS bottom bracket to use with a ROAD double otherwise the large ring would have not cleared the chainstay. Similarly, with an alloy touring frame (again, 135mm rear spacing) that I had, I also needed a 118mm Octalink bottom bracket to allow me to use a ROAD triple/double. So, that's something people need to be aware of with regard to spindle length AND a minor (?) problem with cranks that use external BB cups because of the fixed spindle length.
As Peter said, you will probably need a new BB ... but, as I said, you can re-sell your current crank and/or BB to offset the cost of whatever you choose to buy.

BTW. Shimano has at least one, less expensive "compact" Hollowtech II crank, now, which is slightly heavier (solid arms) & 105-class chainrings.

kensek

So, I have been looking at compact cranks but I still haven't ruled out standard cranks. With a triple I never feel like I use the granny ring, even all hills. Would I be safe then with going with a standard crank?