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FREEWHEEL SRAM Powerglide 950 9-speed 11-32
CRANKSET FSA Vero Forged 52/42/30
165mm (47) 170mm (50-53) 175mm (55 - 62)
I'm trying to figure out this whole gear ratio thing....and :o I'm somewhat numerically dislexic......
Can someone explain what my gears are doing? I was reading about 36 being great for hills.... so I looked at my specs and just got dizzy...
just wanting to know...
ME TOO! I look forward to someone who can enlighten us!Quote:
'm trying to figure out this whole gear ratio thing....and I'm somewhat numerically dislexic......
Okay.
CRANKSET FSA Vero Forged 52/42/30
This is the crankset and chainrings on the crankset. FSA (Full Speed Ahead) is a brand and Vero is the model. Forged means it's steel and heavy. It's a triple crankset with chainring sizes of 52, 42, and 30. The smaller the chainring used on the front, the easier it is to pedal and the higher your cadence will be for a set speed. 52/42/30 and 53/39/30 are common road triple combinations.
165mm (47) 170mm (50-53) 175mm (55 - 62)
This refers to the crank lengths for the different sizes of bikes in parentheses. Tall folks generally need longer cranks, shorter folks use shorter cranks.
FREEWHEEL SRAM Powerglide 950 9-speed 11-32
This refers to the cassette that's used on the back. In contrast to the chainrings, the more teeth the easier it is to pedal and the higher your cadence will be for a set speed. This is because the more teeth the fewer the revolutions of the back wheel per revolution of the cranks. This particular cassette happens to be a mountain bike cassette made by the company SRAM. Road cassettes typically only go to 27 max (SRAM to 28), while mountain cassettes go to 32 or 34.
To get easier pedaling (and to have more gears for us slowpokes up hills), you want smaller rings on the front and bigger rings on the back.
Sheldon Brown has a gear calculator that's fun to play with.
http://www.sheldonbrown.com/gears/
A brand new bike coming with a freewheel rather than a cassette? I don't think anyone has ever made a 9-speed freewheel, so it's probably a cassette.Quote:
Originally Posted by elk
Hey Deb, I have a Roubaix with a 11-27 cassette. Can I get one with more gearing (correct term?) for steep climbing?
The size of cassette cogs and chainrings are measured in the number of teeth. So 42x23 means you're chain is in the 42-tooth chainring up front and the 23-tooth cassette in the back.
Easier pedaling = smaller chainring (front) and larger cassette cog (back). Opposite for harder pedaling.
A long time ago, I sat down and counted teeth on chainrings and cogs, and it helped clarify things, since I'm more image-oriented than number-oriented.
9 or a 10 speed?Quote:
Originally Posted by sundial
I think 27 is as high as it goes for 10 speeds.
I got all that part, but what confuses me is the word SPEED.
I rode 10-speeds in high school. I don't think it's the same thing anymore, right?
Karen
Well, it sort of is, except in the 70s they were talking about the total number of gear combinations, and now it refers just to the rear cassette.
Your 10-speed then had a total of ten total gear combinations available -- probably a double up front and a five-speed in the back. Now the 9 versus 10 speed designation refers only to the rear cassette: so if you have a triple chain ring up front and a 10-speed cassette in the rear, that means you have a total of 30 gear combinations available. If you have a double chain ring in the front and a 9-speed cassette in the rear, you have 18 gear combinations.
But 18-speed and 30-speed sound sort of ridiculous so the terminology has changed. I do see Craigslist ads advertising "27-speed women's bike," though.
SRAM has an 11-28 cassette for 10 speeds in their Force group. No 11-28 for 9 speeds. You'd have to go to a mountain cassette after that. Ilima describes the setup in the OP wonderfully.
Except that, to complicate things even further, you really don't have 30 gear combinations available, unless you intend to cross-chain and wear your components out prematurely. With a triple up front and 10 in the rear, you really only have (you more knowledgeable folks correct me if I'm wrong here) 15-20 gear combinations you can (should) actually use. Doesn't that make this even more fun? ;)Quote:
Originally Posted by xeney
I'm the Queen of Cross-Chaining. Thank goodness I have a compact crank and only 8-speeds :rolleyes:
Kinda makes me want to get a fixie.
SRAM OG-1070, 10-speed 11-28tQuote:
Originally Posted by madscot13
Actually, IRD makes a 10 spd cassette to 34 but you need a rear derailleur with the capacity for it.
Chain close to you as you pedal: easier pedaling (you're in the small chainring at the front and big cog at the back).
Chain away from you: harder pedaling (you're in the big chainring at the front and small cog at the back).
Here's what I don't get about the way cog sets are put together:
There's a small differential between the higher gears, say 11 through 17. When you get into the lower gears, 19 through 27 or 28 or 34 or whatever, there's a much bigger jump between gears, which makes for more difficult shifting under load. Wouldn't it make sense to have closer gears for the situations in which it's more difficult to shift, and spread the gears out more for the range in which it's easier to shift?
Or is that logical only to my own wacky, hill-challenged mind?
That's a good point. I'm considering the 11-34 IRD cassette that SadieKate mentioned. 11-13-15-17-19-21-23-25-28-34. That's a big jump into the spinner gear. I haven't tried it "in person" yet.Quote:
Originally Posted by Kalidurga
Couple of things -
First, the percentage of change. 2 teeth is a much greater percentage of change in the small cogs
Secondly,practicality as you get into steep climbs. Typically you don't really care about one-two tooth increments in the big cogs. You just need a gear, any gear.
One tooth increments are far more noticeable when you're trying to fine tune a gear selection and cadence on flat roads when you're using the smaller cogs.
And soft pedaling enough to change cogs should be easy. It's shifting chainrings that is hard.
Well, then, in addition to being the Queen of Cross-Chaining, I must also be the Duchess of the Hard Uphill Shift ;)Quote:
Originally Posted by SadieKate
If you currently have a 'road' rear derailleur, you'll need to get a mountain rear derailleur to use that cassette.Quote:
Originally Posted by dachshund
Shimano road derailleurs--even if they are the long cage for a triple up front--only can handle 27 teeth max, so that's why the biggest road cassettes from Shimano go to 27. SRAM goes to 28. Now, as far as your wheel hub goes, Shimano and SRAM are interchangeable (not true of Campy). And I have heard that a Shimano RD can be pushed to 28.
For more teeth, like a cassette with 32 or 34 teeth, you must use a mountain derailleur. As far as shifting under load, one thing you can do is get a 'low-normal' RD. This will make the moving to easier gears (bigger cogs) easier, but it will change your right STI (controls the rear) to a configuration opposite of a road or top normal mtn derailleur.
Can you clarify what you mean by "it will change your right STI (controls the rear) to a configuration opposite of a road or top normal mtn derailleur"? "Low normal" and "top normal" are terms I don't think I've heard before.Quote:
Originally Posted by ilima
Thanks :D
I'm using the SRAM 11-28 with my Shimano long-cage RD and triple FD without any issues. Didn't even need to change the chain length.
http://en.wikipedia.org/wiki/Derailleur_gears
Relaxed position
High normal or top normal rear derailleurs return to the smallest sprocket on the cassette when no cable tension is applied.[4] Most Shimano mountain, all Shimano road, and all SRAM and Campagnolo derailleurs are high-normal designs.
Low normal or rapid rise rear derailleurs for mountain bikes are manufactured by Shimano. These derailleurs, introduced in 2004 in the XT and XTR groups maintain position over the largest sprocket on the cassette when no cable tension is applied.[5] On mountain bikes especially, this is an advantage because gear changes tend to be easier and quicker when changing in the spring weighted direction. Changing gears in the sprung direction requires only a light click on the control, and the spring will move the derailleur into place. In road racing the swiftest gear changes are required on the sprints to the finish line, hence high-normal types, which allow a quick change to a higher gear, have become the most common. In off-road cycling the most critical gear changes occur on difficult uphill sections when the rider must not only cope with the hard pedaling, but must also get into a critical riding position to maintain grip and must often cope with obstacles and difficult turns at the same time. In addition, they may be moving at a slow speed and it may be difficult to ease off pressure from the pedals without losing balance. Under such conditions being able to switch easily to a lower gear can make the difference between being able to tackle the section or having to get off and push, and thus the advantages of low-normal changers make them the best choice. From a user interface point of view, they shift opposite to other rear derailleurs. The user 'clicks' the index finger trigger to move to a larger sprocket, and pushes with the thumb trigger to select a smaller sprocket.
I personally run the high normal derailleur on my mtb because mud and debris can crap up the spring of the low normal and then you can't shift at all. It tends to be a love or it leave on normal or rapid rise. Reviews are on both ends of the spectrum.
I only heard of the terms 'low normal' and 'top normal' recently, as I was cobbling components together for a commuter. SadieKate's post gives you an idea of the why behind a low normal RD, so I'll just explain the actual practical mechanics.Quote:
Originally Posted by Kalidurga
With the STI shifters on a road bike, shifting the little lever (not the whole big brake lever) will put you into a smaller ring, front and back. On the front (left shifter), that means shifting the little lever will make pedaling easier, but on the back (right shifter) it will make pedaling more difficult.
With my 'low normal' RD, the right shifter works opposite of that. Shifting just the little lever puts me into a bigger cog making pedaling easier.
Because I live on a big a$$ hill, I decided to go with the low normal for my commuter; mostly for kicks but also because I didn't want to be struggling up the steep (~20%!) pitches with a load and have trouble shifting into an easier gear. When I first start riding the bike I have to remember that the rear shifting is opposite of my road bike, but that's been pretty easy.
This has been a great thread. I've been thinking since last year of building a new cyclocross bike with lower gears in the cog set, and the information here has been very helpful. Since I'm currently using Shimano Sora levers and plan to switch to Tiagra or better on the new bike and would have to get used to different shifters entirely, I wouldn't have the issue of adjusting to the RD shifting being "backwards" with a low-normal setup.
Thank you, ladies, very much.
The IRD 11-34 is also supposed to work with a Campy compact 34-50 and a medium cage derailleur.Quote:
Originally Posted by ilima
That would have to be a medium cage mountain derailleur. If you had a triple up front you'd need a long cage mountain derailleur with that cassette.Quote:
Originally Posted by dachshund
A 'medium cage' road derailleur is for a triple up front and a road (i.e., no more than 27) cassette.
The maximum cog refers to the maximum number of teeth a RD can handle. For road, it's 27/28 and for mountain it's 34.
Capacity refers to the number of teeth between the hardest and easiest gears (biggest chainring minus smallest chainring) - (biggest cog minus smallest cog).
I don't know about the designations for Campy, but Shimano uses SS for road RDs meant for a double crankset. GS for R
That's the most forthright and direct explanation I've ever read. THANKS.Quote:
Originally Posted by xeney
I know about cross chaining so I get why you don't have ex. 30 total gear combos.
whew, I can sleep tonight!
Karen
The BasicsQuote:
Originally Posted by dachshund
http://bluecollarmtb.com/2007/06/19/...ity-explained/
So which Campy derailleur should you pick? Read the yellow box a little way down the page.
http://www.branfordbike.com/cgi-bin/...R_ID=647623406
Branford Bike is my "go to" place for all things Campy.
OK..so 11-32 indicates that the number of teeth on each of the 9 rings is different and the smallest # is 11 and the largest 32? 11 teeth are on the smallest ring.Quote:
Originally Posted by ilima
SO...my spinningest gear is 30/32?
and when I stay mostly on the middle ring up front...it's 42/ and 11 through 32?
and where does the RATIO part come in?
BY the way...this is the Jamis Aurora touring bike.
(thanks for all the info...!!!)
Use Sheldon Brown's calculator http://www.sheldonbrown.com/gears/.
Explanation (from the website):
Gear Inches
The simplest system in common use is the "gear inch" system. This dates back to before the invention of the chain-drive bicycle. It originally was the diameter of the drive wheel of a high-wheel bicycle. When chain-drive "safety" bikes came in, the same system was used, multiplying the drive wheel diameter by the sprocket ratio. It is very easy to calculate: the diameter of the drive wheel, times the size of the front sprocket divided by the size of the rear sprocket. This gives a convenient two- or three-digit number. The examples listed above are all around 74-75 inches. The lowest gear on most mountain bikes is around 22-26 inches. The highest gear on road racing bikes is usually around 108-110 inches. Unfortunately, the handwriting is on the wall for all inch-based measurement systems.
Gain Ratio
I would like to propose a new system, which does take crank length into account. This system is independent of units, being expressed as a pure ratio.
This ratio would be calculated as follows: divide the wheel radius by the crank length; this will yield a single radius ratio applicable to all of the gears of a given bike. The individual gear ratios are calculated as with gear inches, using this radius ratio instead of the wheel size.
An Example:
A road bike with 170 mm cranks: (The usual generic diameter value for road wheels is 680 mm, so the radius would be 340 mm.)
340 mm / 170 mm = 2.0. (The radius ratio)
2.0 X 53 / 19 = 5.58
This number is a pure ratio, the units cancel out. I call this a "gain ratio" (with thanks to Osman Isvan for suggesting this term.) What it means is that for every inch, or kilometer, or furlong the pedal travels in its orbit around the bottom bracket, the bicycle will travel 5.58 inches, or kilometers, or furlongs.
Now then there's Gear Ratios, which may be important in 2 situations. The first is for fixie riders. The ratio (ring/cog) determines how many skid patches may show up on a tire. The more skid patches, the longer the tire wear. The fewer, the shorter, because you'll wear out one part really quickly.
The second situation is for those with climbing bikes (I think it's more relevant on a road or touring bike, because the approach in selecting gearing on a mtn bike etc. is different) in balancing cadence with power output. The gear ratio essentially determines how many revolutions you're going to get of the wheel per revolution of the cranks. It takes a lot less resistance to turn the cranks with a gear that will move the wheel one revolution or less than it takes to turn a 39/17, for example. Your 30/32 is smaller (easier) than a 1 ratio (30/30), so you can compare. However, you get a lot more speed per revolution of the cranks on the "harder" gear, as we all know. So, you may want to consider gear ratios in figuring out how fast you'd need to turn the cranks at a given gear to go X mph. But then, you'd probably still want to use the rpm/mph calculator for different gear setups to figure out what you want. Then, you'd plug in something like this: I can get up this hill with maybe these gears, and I think I can turn the cranks at 60rpm or 80rpm or 100rpm. If so, how fast would I be going in each of these gears? Am I ok with that, or would I rather have to put out more or less power or use different rpms in another gear to go that speed? Or do I want to fight a bigger gear to try to get more speed?
I find it's easiest to stick with the Gear Inches chart. Smaller numbers = easier.
Kali, that's also why there are bigger jumps at the larger cogs. A small jump on the small cog end with be a bigger jump in gear inches than on the large cog end. So while the shift can be hard in terms of jumping sizes of cogs, it gets less and less easy per size of cog, if that makes sense. So if you're running out of gears on that end when you're in the small ring, then you want bigger jumps to be able to feel the difference. When you're trying to fine tune a comfortable cadence on the flat with the speed you want to go, then you want the tightest gearing possible on those smaller cogs to minimize the difference in feel between each gear.