# Redundant Gears



## cda 455 (Aug 9, 2010)

What would be the definition of the term 'redundant gears'?

I'm wondering if I should build with a double or triple chainring and have heard that triple's have many redubdant gears.


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## wim (Feb 28, 2005)

Most multiple-ring arrangements have "redundant" gears. Some people call them "overlapping" gears, which makes them sound better.

Actually, those overlaps can be a good thing. They help cut down on front shifts at a rider's usual cruising speed. Constant front shifting can be an issue with arrangements that have very little overlap, like you see with some compacts. Go to a gear calculator and see what's what.


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## spade2you (May 12, 2009)

Gearing is indeed redundant. That's just the way it is, but you want to avoid cross chaining.

Anyway, compact vs. triple, kinda depends on many things, fitness, weight, bike weight and purpose, etc. Touring bikes generally assume you'll be hauling some luggage, so the low gear can come in handy. On a road bike, usually most riders with reasonable fitness and aren't too heavy can do alright with a double, although I've met a few riders who deal with a lot of long and steep climbs that utilize a triple.


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## aengbretson (Sep 17, 2009)

Redundant gears are ones that have identical ratios. For example, with a 50-39-30 triple crank and a 12-27 cassette (a common setup), I calculated gear ratios by dividing the crank teeth by the cassette teeth for all 30 possible gears and found a 39/21 combo is identical to the 50/27, 30/15 is the same as 50/25. Others that have a difference of less than 2% are 39/25 & 30/19, 39/17 & 30/13, with even more that are within 5% of each other.

The main difference between a triple and a compact setup is that a triple, while resulting in more identical gearings, can provide a closer ratio of gears across a much wider span of available gears. A compact with the same range will have a bigger "jump" between gears. I would advocate a triple if you plan on riding up lots of big hills with a touring bike. For general fitness riding a compact can offer better shifting and less weight.

Of course there is no "right" answer to what you "should" do. I believe that triple is largely irrelevant with modern compact cranksets, but again if you plan on touring with this bike a triple is still a very good choice.


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## JCavilia (Sep 12, 2005)

Redundant (or "duplicative") gears are gear combinations that give the same or nearly the same ratio with different combination. For example, a 52x23 combination is nearly the same ratio as 39x17. All derailleur systems have this to some extent. You can minimize it by choosing cassette patterns that match well with your chainrings. But you can't eliminate it. 

There will usually be more duplications with a triple. But it doesn't matter. If you set it up right the duplications will be in combinations that you really wouldn't use anyway. It does mean that you don't have as many useable gears as you might think (a triple with a 10-speed theroretically has 30 speeds, but it really has only perhaps 22-23 useable unique ratios). 

You pick your equipment based on your needs: what's the lowest gear you need, what's the highest, and what will give you close enough jumps in the range where you usually ride. If a triple is what meets your needs, don't let the redundancy issue scare you away from that.


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## tihsepa (Nov 27, 2008)

I run a 48-34 up front and a 17-19 in the back. Front has a shifter the rear? Not. Just a Paul Melvin. It runs great on all the hills here in the midwest. :thumbsup:


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## Kerry Irons (Feb 25, 2002)

*6 speed?*



A from Il said:


> I run a 48-34 up front and a 17-19 in the back. Front has a shifter the rear? Not. Just a Paul Melvin. It runs great on all the hills here in the midwest. :thumbsup:


Just where did you come up with a three speed freewheel, let alone on with a 17-18-19 cog set?


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## tihsepa (Nov 27, 2008)

Sorry, i wasnt clear. Two rear, on each side. 

Low for hills, high for the flats.


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## wim (Feb 28, 2005)

*Saving 1,000 words.*

Since I didn't answer the OP's question, I decided to make up for it by doing a quick gear chart for my bike and posting it. I run 42/52 chainrings and a 9-speed 12-25 cassette. 

I think charts like this are instructive. You can see at a glance where the redundant gears are and how much overlap you have. You can also see where the larger gaps are. All you need to make such a gear chart is some lined paper, a pencil and a calculator. (There may also be on-line plotters that can do this for you.) As you can see, there's lots of overlap and some redundant gears with those 42/52 chainrings. That overlap, right now and right here, is exactly what I want.

A potential problem with making charts like this is that it's a mild form of overthinking that can quickly turn into a gear calculation obsession. There are people who spend more time figuring gears than riding their bike, so you've been warned.  
.


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## JCavilia (Sep 12, 2005)

wim said:


> Since I didn't answer the OP's question, I decided to make up for it by doing a quick gear chart for my bike and posting it. I run 42/52 chainrings and a 9-speed 12-25 cassette.
> 
> I think charts like this are instructive. You can see at a glance where the redundant gears are and how much overlap you have. You can also see where the larger gaps are. All you need to make such a gear chart is some lined paper, a pencil and a calculator. (There may also be on-line plotters that can do this for you.) As you can see, there's lots of overlap and some redundant gears with those 42/52 chainrings. That overlap, right now and right here, is exactly what I want.
> 
> ...


Good chart, wim. I like to do those, too, because they give you an intuitive, visual look at the relationships. It helps in choosing equipment, but it can help you develop more efficient shifting habits, too.

One thing that can improve that type of chart: use a logarithmic rather than a linear scale. That way, a gap of a given size on the horizontal scale will represent the same proportional difference in adjacent gears, regardless of whether the gears are at the low end or the high end. It makes it even more intuitive.


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## wim (Feb 28, 2005)

JCavilia said:


> One thing that can improve that type of chart: use a logarithmic rather than a linear scale. That way, a gap of a given size on the horizontal scale will represent the same proportional difference in adjacent gears, regardless of whether the gears are at the low end or the high end. It makes it even more intuitive.


Absolutely. Need to get a log graph template.


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## cda 455 (Aug 9, 2010)

Thanks guys, for the responses.

What I was doing/computing when I started this thread (Ask the question) was using Sheldon Brown's gear calculator to try to answer my own question. I was seeing/using MPH as a means of showing redundant gears. If MPH is shown within .4 MPH I would cross out as redundant. 

Would I be correct (For the most part) on my calculations? I started this thread to help confirm and/or correct my calculations.

For example:

.......56........44<--Shimano DuraAce chainring
...........MPH......<[email protected]
11)..36.........28
13)..30.4......23.9
15)..26.4......20.7
17)..23.3......18.3
19)..20.8......16.4
24)..16.5......12.9
26)..15.2......12
28)..14.1......11.1
32)..12.4......9.7
36)..11.........8.6
*^*
*^*Shimano XTR cassette

The numbers in red are redundant because they fall to within .4 MPH of another MPH/gear ratio.


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## wim (Feb 28, 2005)

*Hmmm.*



cda 455 said:


> The numbers in red are redundant because they fall to within .4 MPH of another MPH/gear ratio.


Not exactly sure why anyone would want to do that. But not knowing enough about your cycling, there may be perfectly good reasons.

As a general observation, there's not much front shifting in fast or competitive bicycle riding. While the terrain and the weather sometimes call for the small ring, basically all fast riding and particularly racing is done in the big ring. Trying to weed out "redundant" gears sounds like you're envisioning yourself constantly shuttling back and forth between the large and the small front ring, like a touring cyclist carrying a heavy load over rolling terrain would do.

Let us know what your goals are. Your avatar says "time trialing," but perhaps I'm reading this wrong.


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## JCavilia (Sep 12, 2005)

Several points

First, that's a weird gear set. 56-44 chainrings (unusual on road bikes -- 52 0r 53 with 42 or 39 is more common), combined with a wide-range MTB cassette, is odd. Is there a reason you're looking at that setup? Maybe we'd be more help if you explained what you're building, and for what use. Are you building a tri bike? Even if you are, do you really need that huge 56x11 (133 inch) gear? Do you need that 44x36 (32 inch) low for the hills you'll climb? If you really need that gear range, I'd seriously consider a triple, because you could use a cassette with much smaller gaps in the middle.

Second, while gears can be described in several sorts of units, gear inches is most common, and would be most readily understood here (see wim's chart, for example). You can use any units for comparison, obviously, but speed at a given cadence isn't the way most people do it.

Third, there's no fixed definition of "redundant" -- it's a relative thing.

Fourth, if you're going to use an arbitrary number, you should use a percentage or ratio rather than a linear quantity (as I suggested with my comment about log scales). On your chart, for example, your .4 mph figure would represent a 3.6% jump at your lowest gear, but only 1.1% at the high end. It would make more sense to say that anything within 2.5% is effectively "redundant." -- but it's still arbitrary.

Fifth, you're focusing on the wrong thing, IMO. Redundancy per se is not as important as the range and spacing of your gears.


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## cda 455 (Aug 9, 2010)

JCavilia said:


> Several points
> 
> First, that's a weird gear set. 56-44 chainrings (unusual on road bikes -- 52 0r 53 with 42 or 39 is more common), combined with a wide-range MTB cassette, is odd. Is there a reason you're looking at that setup? Maybe we'd be more help if you explained what you're building, and for what use. Are you building a tri bike? Even if you are, do you really need that huge 56x11 (133 inch) gear? Do you need that 44x36 (32 inch) low for the hills you'll climb? If you really need that gear range, I'd seriously consider a triple, because you could use a cassette with much smaller gaps in the middle.
> 
> ...


*About me:*
The technical aspect of cycling is new to me. For the first 45 years of my life cycling was with either a single-speed or a multiple-speed bike. I never considered the gear ratio's other than 7-speed, 8-speed, 9-speed, and 10-speed. This thread is teaching me about the technical aspects and how to correctly look at gear ratio's. 

Also, I've never owned a road bike. I'm a Clydesdale so I've always owned a MTB or, what we called Tankers back in the 70's, a highly modified steel Schwinn beach cruiser. Which was basically the predecessor of the modern day MTB. 

'Reading' numbers like gear-inches is like reading Russian to me. I have Sloane's book of bicycling and he explains the where-why-what of gear-inches, which I understand, but only long enough to figure out how to read his MPH conversion chart. In Sheldon Brown's gear calculator, you just plug in gear numbers and it tells you the same end results. I used MPH as a way for me to understand the numbers. 

I just used .4 MPH arbitrarily. You suggested 2.5% rather than my 3.6%/.4 MPH as being redundant. That's good enough for me as a tip/suggestion!

You bring up another good point: Redundancy per se is not as important as the range and spacing of your gears. That's something I will study and learn. 

No racing in the near-future. I want to become an efficient, skilled, physically fit, endurance cyclist. Train, but without the stress of wanting to race.

Any suggestions for gear ratios for the mountains and for everything else is welcome.

BTW; I see myself as a Miguel Indurain: Even if I was of elite-caliber in cycling, I still would weigh about 175lbs to 180lbs, monster quads, and be at least 25lbs to 50lbs heavier than anyone else in a TDF. I would keep up in the peloton in the mountains and then make up time in the flats and TT; just like Big Mig did!

*My build goals:*
1) To build a dedicated road bike made of Ti.

2) To find a gear ratio to to satisfy my riding needs/desire. 
A) I live in a valley up against the Rocky MTN range where there's a road that's 16.3 miles long; elevation gain of 3836ft with average grade of 5% and max. grade of 15%. I want to conquer it! That's why I want 'granny gears'. Someone brought up a good point about physical condition; Until I reach my best physical condition, I want ultra low gears to climb said road.
B) Most of my cycling will be done on relatively flat ground. I like sprinting like a bat-out-of-hell on nice, flat, and long roadways. The reason why I want huge chainring(s) is the same as why Miguel Indurain used them: I have huge quads from genetics and years of body-building and powerlifting and I would like to take full advantage of my power. Intervals is what I'm describing. That's why I'm looking at the wide range of the Shimano XTR cassette.
C) An option/possibility would be to have two rear wheels; one with a cassette for the hills and the other with a cassette for everything else. (I just thought of that!).

3) To Build the lightest bike within budget. I belong to a local cycling club and it was suggested to me that weight reduction on a bike is most effective with anything that rotates. So, next to the frame, my budget is going to be focused mainly on crankset, pedals, cassette, chain, wheels, and tires. For example; I might use all Shimano 105 except crankset, cassette, and chain. I would use DuraAce on those. 

4) To build one bike that will last and endure a Clydesdale (Even when I do get down to 180lbs  ). Although carbon fiber is great in and of itself, it has an expiration date unlike other material of the metallic persuasion. If a company has to warn you not to leave your bike frame in a hot car because it might effect the material (Cervelo), I would rather stay with metal because I'm not rich. I own (From new) a 1995 Cannondale Super V1000. I couldn't afford the '96 Super V2000 with the CF swing arm. I was bummed. 15 years later? Those same swing arms are cracking and breaking at the brake-mounts and I am glad I didn't get it! My stem and handle bar will probably be made of Ti (Moots). Even if my household income increased twofold or even threefold, I still would not consider a CF frame. One crash; or the constant environmental exposure will shorten the life of a CF frame. That's just my thoughts/opinion/observation/logic. I would love to own a Cervelo R5ca just for the mountains. Up until last week I was set on what wheels I was going to use: Zipp 404 tubular cyclocross (For using 700X25 tires). But I finally applied my CF logic to it and changed my mind. Even the idea of shaving almost 1.5lbs off of rotating mass wasn't enough to deter me. I'm not rich enough to justify the cost of such 'delicate' material (Which is why I picked Ti). The 'diminishing-returns' logic dictates my reasoning on CF. I'm still going to spend a ton of money, but I think the durability of Ti justifies it. 





> Not exactly sure why anyone would want to do that. But not knowing enough about your cycling, there may be perfectly good reasons.
> 
> As a general observation, there's not much front shifting in fast or competitive bicycle riding. While the terrain and the weather sometimes call for the small ring, basically all fast riding and particularly racing is done in the big ring. Trying to weed out "redundant" gears sounds like you're envisioning yourself constantly shuttling back and forth between the large and the small front ring, like a touring cyclist carrying a heavy load over rolling terrain would do.
> 
> Let us know what your goals are. Your avatar says "time trialing," but perhaps I'm reading this wrong.


How to shift was going to be my next thread  ! Because I don't have a clue on how to efficiently shift or use my gears other than trying to keep a constant cadence. Which is a hit and miss game for me.


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## wim (Feb 28, 2005)

Well, I've got a few thoughts to some of your points, but not all.

- With a mix of flatland riding, 5% average grades and a 15% maximum grade, the triple is certainly a good choice. A 52-39-30 front with an 11-28 cassette should do. Figuring gears like you're doing is basically a waste of time at this point. Go with the tried-and-true for now.

- You're not Big Mig. In my view, it's completely unproductive to copy his style of pedaling or his gearing. The 56T ring will work against you, not for you. What makes sense is to emulate Big Mig's character.

- Huge quads are no guarantee of power or speed on the bike. Power is made with a combination of leg strength and leg speed. Keep in mind that force is applied to a bicycle pedal for a very short time—about 0.25 seconds at a cadence of 60; about 0.12 seconds at a cadence of 120. Also remember that expert riders, even pros, don't apply much force to the pedal at all. Even pro riders cranking out 400 watt of power put only about 130 pounds maximum force on the pedal at that level of power. This combination of very short-duration force and relatively low force is one of the reasons why weight-lifting does little or nothing for the road rider. Don't confuse strength with power—and it's power that's needed at the rear hub to go fast.

- Trying to keep the same cadence at all times is not the way to ride a road bike fast. For some stretches of road, it's impossible to do. Try to ride at differing cadences to broaden your skill. Different conditions call for different cadences. A good road rider can spin up to 120 rpm if needed, cruise at 90 rpm for hours, and climb a super-steep incline at 60 rpm. Noodling around at the exact same cadence all the time doesn't teach you how to do that.

- I remember the late Eugene Sloane's book well. I bought it when it came out in 1970, loaned it to someone and you know the rest. 

Don't overthink cycling. Just go out and ride and be perceptive as to what works and what doesn't. Have fun, first and foremost!


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## cda 455 (Aug 9, 2010)

wim said:


> Well, I've got a few thoughts to some of your points, but not all.
> 
> - With a mix of flatland riding, 5% average grades and a 15% maximum grade, the triple is certainly a good choice. A 52-39-30 front with an 11-28 cassette should do. Figuring gears like you're doing is basically a waste of time at this point. Go with the tried-and-true for now.
> 
> ...


Ah; very good points to ponder. I like your K.I.S.S. approach too.

I'm curious; Why is it suggested to do some workout with weights if what you're saying; "Weight-lifting does little or nothing for the road rider", is true? I've been reading through Bicycling Magazines Training & Nutrition section and they advocate moderate weight-lifting for strong legs: http://www.bicycling.com/training-nutrition/training-fitness/sexy-legs-6-easy-steps . But like I said; I'm a returning student to this sport so I'm definitely open to tips and suggestions. Two things I definitely need to work on is my core and my endurance. 


Wow; Sloane died in 2008 at 91 (I just Google'd it). I have his 25th anniversary edition, 1995. I often wondered if he was still alive.


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## laffeaux (Dec 12, 2001)

CDA, one other thing to consider is "jumps" between gears. The gearing that you show has a wide range, but the jumps are large. Sometimes a gear is too hard and your legs are getting tired from pushing too hard. You downshift. The next gear is too easy so you either spin too fast or slow down. You'd like to find a gear that's in between, but there is none.

Personally, I pick a cassette that has a cassette as small as possible but still allows me to ride the biggest hill that I will likely encounter. Like you, I can climb a 3,500 ft on one hill. I can handle it with a 25T cog in the rear. If I'm tired I may opt for a 27T. I do a ride once a year that has 15,000 feet of climbing - for that one ride I install a 32T cassette. I don't particularly like the jumps between gears with the 32T, but I need it for that ride. I'm happier when I go back to the 25T cassette.

Range matters, but so do the jumps.


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## wim (Feb 28, 2005)

cda 455 said:


> I'm curious; Why is it suggested to do some workout with weights if what you're saying; "Weight-lifting does little or nothing for the road rider", is true?


For many years, there's been a lively debate going on about that, particularly about lifting weights to gain for leg strength. I'm merely on the side of "doesn't do anything for your cycling." Weight lifting, in my view, is simply too far removed from how force is actually applied to the pedal of a bicycle. Specificity ("to get better at riding a bicycle, ride a bicycle") is so important that weight lifting at best is a waste of time. At worst, it can reduce the ability of the muscles to fire at rapid rates for hours, as needed on a bike. Those who oppose this view often appeal to authority ("Lance lifted weights"), but we really don't know if he won races because of it or in spite of it. There's nothing wrong with some moderate lifting to gain some core- or upper body strength, of course.


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## JCavilia (Sep 12, 2005)

> - With a mix of flatland riding, 5% average grades and a 15% maximum grade, the triple is certainly a good choice. A 52-39-30 front with an 11-28 cassette should do.


This is exactly what I was going to advise. I still get away with a standard double crankset, but I live in a place where the hills are short (though some are steep). If I had a 16 mile climb to do on a regular basis, I'd be on a triple.


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## wim (Feb 28, 2005)

JCavilia said:


> If I had a 16 mile climb to do on a regular basis, I'd be on a triple.


Especially if there's also some fast flatland riding. The triple essentially allows you to run close-ratio gearing for fast flatland riding while giving you a bailout ring for steep climbs.


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## cda 455 (Aug 9, 2010)

wim said:


> For many years, there's been a lively debate going on about that, particularly about lifting weights to gain for leg strength. I'm merely on the side of "doesn't do anything for your cycling." Weight lifting, in my view, is simply too far removed from how force is actually applied to the pedal of a bicycle. Specificity ("to get better at riding a bicycle, ride a bicycle") is so important that weight lifting at best is a waste of time. At worst, it can reduce the ability of the muscles to fire at rapid rates for hours, as needed on a bike. Those who oppose this view often appeal to authority ("Lance lifted weights"), but we really don't know if he won races because of it or in spite of it. There's nothing wrong with some moderate lifting to gain some core- or upper body strength, of course.


IIRC; Lance lifted weights when he was an Iron Man but didn't while doing TDF.

For me, I need to bring my core up to par because I had multiple surgeries on my abdomen so my abdominal strength is only strong enough to hold my torso up. My body compensated by 'building' up my lower trapezius muscles and latissimus dorsi muscles. 

I agree; once the muscle groups are up to par, additional weight lifting probably doesn't benefit much. Non weight-bearing exercising would take care of keeping them strong. Of course, 'Up to par" is relative.


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