Thinking about a new crank set...

rides4sanity

Let me preface this by saying that I am not mechanically or technically inclined, so my lingo may be off, but I'll do my best...

I have a Madone 5.2 with a compact 50/34 crankset and a 105 11-28 cassette. My previous bike was a standard double, set more for flats with a tighter cassette, not sure on specs. I miss the speed. I let them talk me into the compact when I got it, but now I'm stronger on the climbs and run out of gear on the flats I'm thinking of changing it up a bit. LBS mechanic is looking into bumping large up to 53, but he isn't sure if the drop to 34 will be to big.

I don't really know what to ask for, I'd like more top end speed, and being that I'm stronger could probably deal with a little less on the climbs, but don't want to lose too much there being that I live in WV.

Any suggestions? Please use small words. :ohwell:

Cyclink

I'm the wrong person to ask. To me, compact cranks are a marketing gimmick to help sell bikes to newer riders who cannot push the larger gears.

I ride with a lot of people who bought bikes with compact cranks and end up swapping them out when they get faster. They are never happy about the cost.

53/39 or 52/39 are the standard crank setup. I'd recommend one of those.

You can spin up most climbs under 12% in a 39-28 just fine.

FatDadSlim

Late last year I changed my complete chainset from a compact 34/50 to a double 39/53, whereas i could easily climb most of the local mountains on the 50 chain-ring, i struggled to keep up with other riders when descending, the 53 has changed this although it does take some getting used to.

i guess the only issues with a 34/53 set-up would be getting the chain-length correct, give it a go and see, nothing to lose, if it doesn't work out then change the inner-ring to a 39.

(i also changed the rear to a 11-28 at the same time, this was 12-27 on my compact set-up)

Edit:
have a read through this... http://www.bikeforums.net/archive/index.php/t-465391.html

cloggsy71

... as a wise man once said to me "unless you're spinning out regularly on the 50/11, then there's no point switching up to a 53 on the front!"

I've kinda stuck to that TBH!

What is your crank arm length?

rides4sanity

I'm not opposed to changing big & small, just not sure what the benefits are compared to the Holy crap now I have to climb with less.

At the end of last season I had to keep a ridiculously high rpm to hang on the flats in my largest gear. It wears me out. I do run out of gears on the climbs, but I alwasy did on my old standard also. I think I can adjust.

Maybe next dry day I'll drag the old steel, standard double LeMond, "Biff" off the trainer see how I do on the hills. If I can swing it on Biff, Roxy will be a breeze. Unfortunately, I think Biff needs some shifters and tires before he's road worthy. Maybe he can pull a short, close enought to home to walk back kind of trial.

narak_lol

Not really recommend a combination of 53/34, the shifting will be clunky and likely will have problem with front derailleur with a gap that big.

Probably better to stick with the more normal combinations 52(or 53)/39 as Cyclink said or compact as you have now.

Spinning out at 50x11 @ 120 cadence will give a top speed of 68+km (42+miles) this is seriously fast you are awesome!!! The compact is probably fine so depends on your riding style and which way you want to play :flowerforyou:

rides4sanity

I never hit those speeds on the flats. I am definitely over 100rpm, but maybe all in my head. I just know my cadence is way faster than those dropping me off the end.

narak_lol

I don't even hit 4x unless on descent

Gapwedge01

Spinning out at 50x11 @ 120 cadence will give a top speed of 68+km (42+miles) this is seriously fast you are awesome!!! The compact is probably fine so depends on your riding style and which way you want to play.

:glasses: :glasses:

TheBigYin

One thing to remember, the "old school" chainring combo's of a 53/39 originally came about because in the pre-freehub era, you a 14T sprocket was standard and 13T (and the occasional 12T) rare and exotic birds indeed.

With the old-school gears 53/39 and 13-24 you'd have a gear range of 107.5in - 42.9in (assuming a cadence of 90rpm that's 28.8mph - 11.5mph)- on a Modern compact setup a 50/34 and 12-28 will give 119.9in - 32.0in. (again at 90rpm that's 29.4mph - 8.6mph) which is quite a large difference at both ends of the scale.

Of course, as the 12T and subsequently 11T freehubs came into play, the Pro's dropped them in, keeping their "standard" chainrings. In fairness though, they ARE riding down the side of an Alp, can spin all day at 130-140rpm cadence, and can make use of the gearing.

TheBigYin

Also - another consideration it that the typical front mech will have a "range" of 16T from large to small ring - or 50-34. Triple chainrings generally demand a special front mech that can cope with a larger jump (i.e. to haul the chain up from the small to big ring).

Recently, one or two manufacturers have been shipping what they refer to as "sprinters compacts" - a compact BCD of 110mm but with 52/36 rings - which gives a bigger top gear, at the cost of a slightly bigger climbing gear - and still maintains the 16T gap for the front mechanism...

rides4sanity

Thanks y'all!

katozdad

Bump...

Perhaps it is just my naivety, but this is one of the reasons I am holding off buying a new bike. I spend a lot of time in the top gear on my bike and don't want to be going for an expensive swap when I find that I am quickly running out of gears on my new one. Perhaps I am not looking in the right place, but I don't remember seeing any new bikes without a compact crank... where are they?

scott091501

I see a lot with standards, lots of compacts, and a few triples. I don't really see the need for a triple, but maybe it's where I ride. I ride exclusively in the big ring here in my part of Texas.