Compact Gearing

[Jay H]

Funny, since I'm in the market for a touring bike, narrowed down the options to a Surly LHT with a standard triple and a Salsa Vaya which has a compact double. The LHT has a much lower gear inches than the Salsa with it's double, while the Surly has Barcons friction/index shifters versus the STI on the Vaya and the LHT uses cantilevers and the Vaya has discs.

The discs vrs cantis is my major deciding factor for me. I'm sure the disc brakes and STI explain why the vaya is a good $400 more than the LHT...

Decisions...decisions...

p.S. Tim describes what is commonly known as a "Flip Flop Hub".

As a tourer, I advice those that are in the market for a bike, to check to see if it has eyelets and brazeons for fenders/racks. Most don't and down the line when you decide to commute, it's a whole lot easier/cheaper when you can buy off the shelf racks and fenders. I did it the hard way....

 

[IndianChris]

So I've had the FP-1 for a week now. Rode it twice. Love it.

It came with a 50/34 and I had the rear cassette changed from a 12-25 to an 11-25 for that big gear. The low gear however is not as low as what I was riding the hills with on my modified mountain bike - expected. The 34/25 on the FP-1 is bigger than the 32/30 on the mountain bike (I never used the granny gear - 22 tooth front chain ring).

Maybe in the future I'll change the rear cassette again from the 11/25 to an 11/27 for the hills. Although I'm sure I'll get used to the 34/25 with time.

 

[iceNsnow]

I live for the eleven!

Although I don't climb as well as I used to, I live for the descents. It is easy enough to spin out an 11 so I'd be unhappy w/ the compact drive.

I ride a straight block 21x11, unless I do a group ride - then I switch to a 23 or 25x11. It seems that the compact drives are popular, but not me, not now!

 

[bikehikeskifish]

I ride a straight block 21x11, unless I do a group ride - then I switch to a 23 or 25x11

Can I ask why? I have known people to have "criterium wheels" and "climbing or road race wheels" with different gearing. Am I correct in assuming your group rides go hillier?

For reference, there is this: http://www.sheldonbrown.com/gears/ (AASHTA, R.I.P. )

Tim

 

[Jay H]

So I've had the FP-1 for a week now. Rode it twice. Love it.

It came with a 50/34 and I had the rear cassette changed from a 12-25 to an 11-25 for that big gear. The low gear however is not as low as what I was riding the hills with on my modified mountain bike - expected. The 34/25 on the FP-1 is bigger than the 32/30 on the mountain bike (I never used the granny gear - 22 tooth front chain ring).

Maybe in the future I'll change the rear cassette again from the 11/25 to an 11/27 for the hills. Although I'm sure I'll get used to the 34/25 with time.

A mtb gear with a 22inch granny, 26" wheels has a gear inch of like 11.x ish and that is quite ungodly low for anything resembling a road. No surprise that you never used it on the road!

Would you really notice a one tooth increase in the rear cassette?

jay

 

[bikehikeskifish]

Would you really notice a one tooth increase in the rear cassette?

2.8 MPH at 90 RPM - 31.1 MPH (53x12) to 33.9 MPH (53x11), or 9% (700x23 wheels)

Tim

 

[Jay H]

..in that big of a gear (53x11), I don't think I'm coming ever close to 90rpms

But I'm a tourer and have no interest in top end speed...

jay

 

[spencer]

I love it when you talk dirty like this...

I ride a triple (30-42-52 and 12-25) and am very glad for the range. I spend most of my time on the middle and outer rings but since I'm usually 80 pounds heavier than my riding buddies I appreciate the lower gears on the hills. They don't dare laugh at me b/c once I catch them on the flats they love to sit behind me when I'm cruising in my 52x12 or 13.

I put a 12-26 cassette on my cross bike with just a 41-tooth ring (1x9). I spin-out somewhere around 26 mph and have to stand for moderate hills but I love the compromise between simplicity and flexibility.

 

[iceNsnow]

Can I ask why? I have known people to have "criterium wheels" and "climbing or road race wheels" with different gearing. Am I correct in assuming your group rides go hillier?
Tim

Tim - I don't have a good excuse really. I just happened to have the cassette around and figured I'd use it for training Somehow I've actually gotten to really like the challenge.

 

[jniehof]

2.8 MPH at 90 RPM - 31.1 MPH (53x12) to 33.9 MPH (53x11), or 9% (700x23 wheels)

And a 30% increase in power output. Close gearing up high is a Good Thing.

 

[Stash]

Discussing a bike for my daughter today at the bike shop. She hates hills so I was leaning toward a triple for her but, listening to the mechanic and thinking about ratios, I don't see a huge difference between the triple and compact and not having that long rear cage from the triple hanging down and getting easily bent is a major plus for the compact.

 

[IndianChris]

Would you really notice a one tooth increase in the rear cassette?
jay

Well, a two tooth increase from 25 to 27 on the rear cassette would reduce the gear inches down by almost 3 inches. How much of an advantage that is, I'm not sure but it would help a little when looking for one more gear on a steep hill.

 

[bikehikeskifish]

Well, a two tooth increase from 25 to 27 on the rear cassette would reduce the gear inches down by almost 3 inches. How much of an advantage that is, I'm not sure but it would help a little when looking for one more gear on a steep hill.

The difference between 25 and 27 is 12.5%. Here are the numbers for a 50/34 which is the cited size of the compact front chainrings above. The difference is 4.1 inches in the 34 and 6.1 in the 50 - more than 3.

Gear chart using Gear Inches
For 700 X 23 / 23-622 tire with 175 mm cranks
With 10-speed 12-13-14-15-16-17-19-21-24-27 Cassette
	50	47.1 %	34
12	109.5		74.5
8.3 %
13	101.1		68.7
7.7 %
14	93.9		63.8
7.1 %
15	87.6		59.6
6.7 %
16	82.1		55.8
6.3 %
17	77.3		52.6
11.8 %
19	69.2		47.0
10.5 %
21	62.6		42.5
14.3 %
24	54.8		37.2
12.5 %
27	48.7		33.1

You can plug in everything you know at http://www.sheldonbrown.com/gears/ and get these numbers yourself.

Tim

 

[IndianChris]

Interesting. Lotta info there.
Your data shows a 24 tooth cog though, not a 25 like I was referring to. I still come up with a difference of about 2.7 inches.
(34/25) x 26.3 = 35.8 inches...as opposed to (34/27) x 26.3 = 33.1 inches.
Maybe I'm wrong.

 

[bikehikeskifish]

Hah, I didn't notice Here's the only combo ending in 25-27 w/o going custom:

Gear chart using Gear Inches
For 700 X 23 / 23-622 tire with 175 mm cranks
With 10-speed 16-17-18-19-20-21-22-23-25-27 Cassette
	50	47.1 %	34
16	82.1		55.8
6.3 %
17	77.3		52.6
5.9 %
18	73.0		49.6
5.6 %
19	69.2		47.0
5.3 %
20	65.7		44.7
5.0 %
21	62.6		42.5
4.8 %
22	59.7		40.6
4.5 %
23	57.1		38.8
8.7 %
25	52.6		35.7
8.0 %
27	48.7		33.1

I went for a 40 mile ride today and I used my 53x12 on some downhills spinning out at about 37-38 MPH... I can get a bit faster as the season goes along.

Tim

 

[Jay H]

Well, a two tooth increase from 25 to 27 on the rear cassette would reduce the gear inches down by almost 3 inches. How much of an advantage that is, I'm not sure but it would help a little when looking for one more gear on a steep hill.

You're talking about the other end of the spectrum, I could justify a few more teeth if you feel you could use the lower gears. On a triple, it could be useful for a higher gear just to avoid having to shift into the big ring from the middle in some situations, but IMO, an added high gear on a double is a little less 'useful' and perhaps a little less value for the all-precious dollar. But that, of course, is up to you.

Unlike Tim, I coast down hills if I am going anywhere over 40mph and there is a section on my old commute that I could coast at 40mph....

Jay

 

[IndianChris]

Yeah, I have a hill around here that I can coast down at around 40 if I keep off the brakes. Crazy.
Hit 50 coming down the south side of Greylock -

Be safe.

 

[HAMTERO]

Hah, I didn't notice Here's the only combo ending in 25-27 w/o going custom:

Gear chart using Gear Inches
For 700 X 23 / 23-622 tire with 175 mm cranks
With 10-speed 16-17-18-19-20-21-22-23-25-27 Cassette
	50	47.1 %	34
16	82.1		55.8
6.3 %
17	77.3		52.6
5.9 %
18	73.0		49.6
5.6 %
19	69.2		47.0
5.3 %
20	65.7		44.7
5.0 %
21	62.6		42.5
4.8 %
22	59.7		40.6
4.5 %
23	57.1		38.8
8.7 %
25	52.6		35.7
8.0 %
27	48.7		33.1

I went for a 40 mile ride today and I used my 53x12 on some downhills spinning out at about 37-38 MPH... I can get a bit faster as the season goes along.

Tim

11-28,12-27 and 12-25 cassettes available in Ultegra and D/A.

You guys might want to check out this bike forum:

http://www.velocipedesalon.com/forum/index.php

 

[bikehikeskifish]

11-28,12-27 and 12-25 cassettes available in Ultegra and D/A.

I meant "the only ones available in a pull-down on Sheldon's web-based gear calculator", not necessarily the only ones manufactured

I will point out that the larger the two rings, or the smaller the discrepancy, the longer your chain will last, especially on the front, which is an advantage of the double over the triple (or so I have been told by the bike shop mechanic.)

Tim