Which Compact 34-50 or 36-50??

I run the FSA Gossamer compact MegaExo crankset. It is nice with 34, 50t. I think you should be fine with a 34t for the small ring. I am around your weight, and I use it on tough climbs a lot! And I wouldn't want to be anywhere without it.

I paid around $180 for it, but a good bike shop should sell it to you for $166, that is if they keep current with online prices.

The only complaints, even if they aren't complaints (which they aren't for this price range) is the fact that the bearings aren't the smoothest, but that could be solved later by buying a better model bottom bracket from FSA. And also the weight of the system, but hey I am no weightweenie, and I don't feel like spending $250+ for something that is lighter.

AussieRob said:

Has anyone made the move to compact? How do I know if I want a 34 or a 36? I do weigh 180 lbs and will be racing in the hills. Having said that I can turn the 36, but...

If you could give me an idea of what you paid and where you got it from I would appreciate it.

Thanks

Rob

36x27 is generous and easier than 34x25. both, though, should get you up just about any hill.

I used to ride on a FSA Carbon Compact (34-50) before I got a new bike. I started with a 34 but switched the ring to a 36 to get a higher gearing but not as high as a standard 39. There wasn't that much difference in climbing, but it was more notable in the flats as my pace was picked up a little more with the 36. If you can turn the 36, you should be fine. Plus you can always get a cassette with 23-11 or something similar to get the almost the same gear ratios as a standard 39-53 x 27x12 when you want to go faster. I purchased my set at Colorado Cyclist for like $250 on sale.

Thanks guys. I should have said it was always my intention to use a 23-11. I am racing and want to keep my cadence up on the hills. You loose a bit of top end with a 50 - 11, but then my chances of getting to use my sprint are probably increased by having a compact. A decent sprint is nothing if you can't get to the last Km with the bunch.

I have a 36/50 compact on my road bike, and a 34/50 compact on my commuter bike.

I find that the 34 is a little low when not loaded down with equipment/gear, and my 'cruise' pace tends to be really high on the 34 ring, or a lowish gear on the 50.

A 36/50 also has the same tooth difference as a standard 39/53 front chainring setup, which may influence the quality of your front derailleur shifts (depending on what front mech you have; some can be clunky when shifting between chainrings of significantly different size as they were never designed for it)

Your best bet would be to plug some gear ratios into a spreadsheet and see what ratios differing combinations give you and how those ratios agree with what you want. I don't think anyone can tell you which is better.

When I did the calc, I found that 50/36 and a 12-25 in the rear gave me what I wanted better than the 53/39, 12-25 I'm using now. The difference isn't huge, but it's significant, especially on the mountain rides. So, I'm waiting for my new crankset w/ 50/36 to arrive.

forgot to add (and it's not letting me edit the post for some reason)

rek said:

A 36/50 also has the same tooth difference as a standard 39/53 front chainring setup, which may influence the quality of your front derailleur shifts (depending on what front mech you have; some can be clunky when shifting between chainrings of significantly different size as they were never designed for it)

That being said, the commuter has a 34/50 compact crank, and the chainrings still shift perfectly with a bog standard Tiagra front derailleur...

not with my tiagra derailleur. That is why I am getting a C-16.

Agree with alienator. Look at your cadence and climbing speeds on your typical hill and figure out what gear you really need to get up the quickest.

To me, if you're moving to a compact with an 11-23, the 34 ring is the choice. 36 just sounds too close to 39 to be worth making the switch, since it only increases your cadence by 8.33%.

EG, if you're climbing at 60 rpm now, you'll see 65 rpm with the 36 tooth (at the same speed), and 69 rpm with the 34. Which sounds better to you? With either choice, you'll be in your 50 ring for all the fast pack stuff anyway.

Rob, spare chainrings are not that dear, buy a range, say, 39, 36, 33. I have a spare middle 39 & 38 TA on the shelf for my (42) Triple. 🙂