I'm thinking of replacing the drivetrain on my giant tcr c2 2007.
It has 39/53 crank and a 12-27 cassette. I'm looking to improve my climbing gears.

The options are to put on a 12-30 cassette. To do so will require a new derailleur(shimano 6700 med cage) The chain and cassette will need to be replaced soon anyway. Or replace the chainrings to a 36/52. I'm not sure if that's possible.

The shop said option 1 would be about us$250. Would I gain enough for the expense? They seamed reluctant to explore the second option.

I could buy a new bike but that may not go over well with the CFO

Go 50/34 w 12-32 cassette.

the second option, changing the chainrings by a mid compact, will accomplish absolutely nothing. that's why they don't want to do it. Even going to a full compact 50/34 won't make that much of a difference. changing the cassette will make a bigger difference immediately for less money and much less work. what drivetrain do you have now?

why only a 30? go with a 32 cassette in the rear and a long cage DR, and call it a day. there are guys on the web putting up to 40t cassettes on road bikes if you want to get serious. $250 is WAY TOO MUCH to pay for this work. get another quote or order the parts and do it yourself, it's super easy.

$250 for a new rear Derailleur and cassette seems a bit steep. Its maybe $150 in parts and doesnt take a whole lot of time to do. Maybe im wrong, i try to do as much as i can myself, so im a bit out of touch with shop prices, but $100 to slap on a RD, Cassette and Chain and set up the RD seems like a bit much.

If you are handy at all (even just a little) i second doing it yourself. Very easy to do, would take maybe an hour (and thats really on the long end) and theres a million tutorials on youtube and the interwebs to guide you through.

The difference in GI between 39x27 and 34x27 is almost 15%, how will that not make much of a difference?

sheldon's shows it as 14.2%, which is almost 14, not almost 15 . . . ok now I'm just being a PITA for the fun of it

he asked about going from a 39 to a 36 not a 34, and even all the way to 34, 15% isn't that much when you consider that just changing from 27 to 30 is almost 12% and a 32 is another 6.5%, so a simple cassette and DR change would give him 18% for half the money or less. no brainer.

Take look at sheldon's gear calculator - select your chainrings and cassette or manually enter the numbers, select wheel size, and select units (MPH, gear inches, gain ratio, etc.) It'll produce a grid that allows you to compare spacing and ratios with percentages between the columns and rows for easy reference. This is what most of us are using to come up with these numbers for you.

Sheldon Brown's Bicycle Gear Calculator

You brought up the 34 though, and a 12-32 comes with huge jumps. So not a no brainer. I'd rather ride 50/34 12/27 any day over 53/39 12-32

check this out - durianrider is all about climbing and cadence, he advocates HUGE cassettes

Mod Warning. Contains R-Rated Language

Agreed - I did ask what the OPs full drivetrain setup is currently, but he has not responded. This would allow us to offer more optimal alternatives by changing specific components that he already has.

While option 2 is great in theory, I am not aware of any companies making 52/36 chainrings for 130 bcd cranksets.

And getting new chainrings almost cost as much as a crankset especially if you use Shimano rings. You can easily find a used compact crank for less and even new 6800 cranks are around $150 from UK. You can get 10% off first order at PBK and bing it down even more

2 more double chainring combinations to consider ..

Popular 50-34, and less common 46-30. both involve buying a whole new crank-set and BB.

52 36 would be buying a crank-set as sold, 46-36 or 50-34 and buying the other sizes of chainrings..

decades ago I built up a 52-36 combo... the top gear on the rear, was a 13t, back then..





./.

In general, compact 34/50 makes more sense but as above, use a gear calculator and do the math. What is ideal gearing for you may not be ideal for me or anyone else for that matter. Too many variables to jump to conclusions.

It has a race face crankset with 39/53 rings 12-27 cassette and ultegra derailleurs

130bcd or 110? 10spd or 11? what bottom bracket do you have?

in any case, you can get new 11spd compatible BB and compact ultegra crankset for $175 or so with free shipping from nashbar, less if they have a sale. if you go 105, which will still be better than you have now, you could get it down to like $130, that's for the cranks and bottom bracket, everything else you could leave alone. it should still work just fine with your 10 speed chain.

because 11spd is so available these days, the 10 spd stuff has actually gotten more expensive.

You guys do realize that bike parts cost money right?

Shimano Ultegra Long Cage RD: $60
Shimano Ultegra 6800 Rear Derailleur | Competitive Cyclist

Shimano Ultegra 11-32 Cassette: $55
Shimano Ultegra 6800 Cassette | Competitive Cyclist

Shimano Ultegra Chain: $22
Shimano Ultegra CN-6701 Chain | Competitive Cyclist

Add Tax

From my experience, bike shops charge around $60-$100/hr for labor.

$250 really isn't that far out of the ballpark.

Like I said, $150 for parts, but i think $100 in labor is steep. Even at $100/hr (which is pretty high) There is no reason RD, cassette, and chain replacement should take an hour. Unless im missing something, a decent mechanic should be able to do it in 30 min, tops. Never said the price was crazy, just seemed like a bit much for whats being done.

Not everyone knows how to setup a RD or wants to bother with it. Not everyone has a cassette removal tool.

I know. I do my own repair work too, and $250 seems pricey when you know how cheap you can find things online and have all the tools at home, but if you have no idea what you're doing, $250 doesn't sound outrageous.

That said, the cassette I just bought for my bike was over $250 alone. Grams, or the lack there of, are expensive!

I believe he is on 10 spd, not 11, so the 6800 stuff won't work. Even if that is true, IF he is on 6800, then 5800 105 cassettes and derailleurs would work the exact same for much less money. Cassettes are $35, Long Cage RDs are around $50. They work perfectly with Ultegra, and the only difference is cost and a few grams. Art's Cyclery did a whole writeup on this, and basically said go with 105 cassettes and DRs, Ultegra cranks and chain and BB (for stiffness and wear resistance), DA if you can afford it. The shifters are all the same, and go with DA cables as that makes the most differences.

Ugh my grammar is terrible, must be all the crabon I garbed for dinner - hopefully I don't assplode.

A 9 speed mtn bike RD will work with road 10 speed shifters and are cheap. Then you can run any rear cassette you want 11-36 for instance.

If you are not racing, or competing, I'd suggest a 30-46 compact. 46 is good enough for most flats. It might be too slow if you want to speed up down hill, or ride in a slipstream of a truck going over 50 km/h, but apart from that, it's fast enough. The chain will run pretty straight in mostly used combos.

30 small ring allows a very good climbing gear, as well as mounting a tightly spaced cassette on the rear, without loosing climbing ability.

A. He said Ultegra (Shimano 6700) derailleur, considering the $250, I'm assuming the shop is going with a full Ultegra drivetrain replacement, minus crankset.

B. I quoted prices that were quickly available while I was at work. Prices are about the same. In fact, you said yourself that 10spd is actually getting to be more expensive than 11spd.

C. The point I was trying to make was that the shop pricing wasn't that outrageous, all things considered. Yes, you can swap out the components for much cheaper, doesn't mean the OP will or has to though.