kreative

I have a Specialized Tarmac with standard double (Shimano 105 52/39), and thinking about swapping out to the compact 105 (50/34) for easier climbing - is this possible? Would I just swap chainrings, chain, and adjust derailleurs?

AngryScientist 

you most likely cant just swap chainrings, the bolt circle diameter is different, you'll need a new crank, but a 105 one should be able to be sourced pretty cheaply

kreative

^^thanks, I think I just found out about the BCD's, standard being 130, and compact being 110 right?

procrit

Why not just get a 27-12 cassette? Cheaper and easier in my opinion.

kreative

My bike has a 12-27 cassette on it standard.

Eclectus

A standard should be fine. I had to switch to a compact at older age, but but if you don't have gray hair like me, you should be able to crank a 52/39, or even a 53/42, without too much problem up some pretty steep hills, especially if you've got a 27 on the back.

I used to do Colo and backside-Sierra climbs with 39/21. Unthinkable for me today. You need to test yourself on some climbs of the grades and altitudes you want to take on, and see how it goes. There's nothing wrong with having a 52/39 for your local rides, and having a backup 50/34 (or even a triple) for rare monstrous marathons that you are waay steeper and/or higher altitude than you are used to riding.

(You can even switch-out RD to MTB and 33-34 cogs if you really need it.)

Don't be afraid to modify your drivetrain for different conditions.

umd

Age has nothing to do with it, some people just aren't as strong as other people. What a concept!

OP, as was said, you just need a compact crank. Remove old crank, install new crank, lower front derailer, and done. Depending on chain length you may need to shorten (or replace) your chain, but it's probably not necessary.

kayakdiver

Follow this advice and you'll be golden.

Hot Potato

I sure hope bike shops take those old cranks in trade. Within the next year I will be trying to find an inexpensive standard double to swap on a bike that comes with an OEM compact. Perhaps I will try to find someone to swap with. But I have thought about owning both, to do what eclectus said. Are they really that easy to change?

kayakdiver

If you have 10 minutes... You can swap the crank AND drink a beer when finished.

Hot Potato

Well, just as long as it isn't as hard as adjusting a derailluer. Then I can handle it. Oh wait, you do have to adjust the derailluer after the swap. AAAAARRGGHHH!

bikeybikebike

I'm actually doing this myself for two reasons: I'm a big baby and i like compacts, and my current cranks are 2.5 mm too long. Yes, I can tell.

What happens if your derailleur can't be lowered farther? IE. It's at the bottom of the braze-on?

ScrubJ

As stated above.

My LBS regularly does this for several of their customers depending on where they will be riding. No big deal.

umd

Then I guess you are screwed.

The SRAM FDs have two holes, you just bolt it on at the upper hole and it lowers the whole thing. Don't know about Shimano or Campy.

Eclectus

When I was umd's age, I could whip his ass. I'm just making this up of course. He is so fantastic, who can keep up with him?

I can say that at age 27, I could do a lot more than at age 57. If you need lower gears, for climbing the Rockies or backside Sierras, or Midwest 25-35 winds in your face, gear down. Don't be ashamed. Most cyclists won't do this s***, the ones that pass you, you have to decide, if you're their age, do you want to get into better shape? if you are 30 yrs older than they are, and want to beat them,
it's probably not going to happen.

Give umd +25-30 years, when he's in his in his mid-to-late 50s, he is going to realize age makes a difference? I think so.

exRunner

I just went the other way on a Allez. Just like UMD said. I changed the BB because I was there, and replaced the chain because for $35 its cheap insurance.

As far as age goes, I agree with UMD again. It does not determine what you need.

BTW, a the 2010 5600L 105 crank is a thing of beauty. So much so that I didn't want to put it on the bike, just set it in my office on a shelf for display.

Quel

For what it's worth, a 53/39 with a 12-27 is pretty close to a 50/34 with a 11-23 in terms of gear inches. I'd probably think about making that switch if it wasn't going to cost me a significant amount of money to do so.

umd

Will age make a difference for me? Probably. I don't dispute that someone will generally get weaker as they get older, but compared to other people, is age the determinant in how strong someone is and what gearing they should use? No. There are very strong older people and very weak younger ones. The strongest of the young people will be stronger than the strongest of the old people, but the strongest old person will be stronger than the weakest young person. There are plenty of "old" people twice my age that can race circles around me. Consider that M35+ and M45+ races are usually way faster than open-age cat 5, 4, and 3 races (not not usually faster than 1/2). The 55/65 races do decline a little, but probably still usually faster/stronger than the 5s.

DinoShepherd

Re: Age

In the very early '90, I was (I thought) a pretty hot college and Cat III racer in SoCal. Very serious competition in SoCal.

I was out on a training ride and got my @ss absolutely handed to me on Dulzura Hwy. by a 50+yo Master's Racer. Turns out he was not only a professor at UCSD, but a National Champion on the track.

Has been my inspiration for staying fit ever since.

-Z

umd

I should add that I only started riding a few years ago and only started seriously training in the last year or so, so I don't think I've reached anywhere near my full potential yet. I'm sure I will decline from my peak fitness as I get older, but if I am not yet at my peak fitness, I could theoretically be stronger/fitter in my 50s than I am now.

roadwarrior

I switched to a 50 big ring and changed my rear casettes to 11-21 as I have short steep rolling hills and it's a lot more comfortable. The good news is that I have Hollogram and the crank and spider are two separate pieces...so the Cannondale rep gave me a smaller spider and all I needed to get was the chainring.

kreative

Wouldn't you have to change the BB as well since the BCD is different (130 vs 110)?

kreative

Thanks for the replies. I'm still debating on this issue, whether to stick it out and train to use the std. double, or to swap out for a compact. My rear cog is 12-27T.

ls01

Or what you can do.

Jakedatc

As long as the BB is compatible it shouldn't matter. I switched a while ago. took 1-2 links off my chain, lowered FD a bit. i have 12-27 9 spd cassette and haven't looked back since. I just did swap my 34t inner for a 36. we'll see how i feel about that once i hit some steeper hills

I'm the direct opposite of a clyde so i am built for high rpm than pure thuggary.