# Gear Ratio -- Double/Triple



## lcecere (Dec 19, 2009)

Good afternoon.

I am considering buying a new road bike, a Trek 1.5. They offer it in a double and triple chain, and the shop has given me all the gear ratio information. The triple is 50/39/30 and the double is 50/34.

Unfortunately, I'm not sure I quite understand the data and hoping to have some help.

I should mention I bought my first road bike last year, a used Trek 2100 which has a triple and I live in Central Vermont which has plenty of hills. I rode about 1,200 miles last season. And while I hate to admit am middle age and not planning on doing any racing.

Any input would be great.


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## dgeesaman (Jun 9, 2010)

Those are the number of teeth on the front chainrings. 50/39/30 is common for triples, and 50/34 is what they call a compact double. (Strong, light riders often prefer the traditional double that has 53/39 or something similar, but most of us amateurs just don't benefit from that much gearing.) So assuming they have the same 12-27 cogs on the back, the difference in the range of the bikes is based on the front rings.

Going up a steep hill on the triple, you can gear as low as 30 in front and 27 in back. On the double, your lowest gear is 34 in front and 27 in back which means on the triple you can get 12% more climbing power than the double.

Going on a slight downhill, both sets top out at 50 in front and 12 in back. No difference there.

I suggest you compare these to the teeth on your triple, but generally triples are 50/39/30. So if you encounter hills where you use the small ring in front and the big cog in back, you probably wouldn't have quite that much gearing if you switched to the double. On the other hand, if you don't ever gear down that far I'd suggest you try the double.


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## PJ352 (Dec 5, 2007)

dgeesaman said:


> Those are the number of teeth on the front chainrings. 50/39/30 is common for triples, and 50/34 is what they call a compact double. (Strong, light riders often prefer the traditional double that has 53/39 or something similar, but most of us amateurs just don't benefit from that much gearing.) So assuming they have the same 12-27 cogs on the back, the difference in the range of the bikes is based on the front rings.
> 
> Going up a steep hill on the triple, you can gear as low as 30 in front and 27 in back. On the double, your lowest gear is 34 in front and 27 in back which means on the triple you can get 12% more climbing power than the double.
> 
> ...


Great info provided here, but IMO the bottom line is the bolded statement. Assuming the 12-27 rear is comparable to your current bike, if you ever find yourself in the 'granny' gear (~30T)/ 27 combo, opt for another triple, otherwise the compact double should be fine (and is actually a close compromise to the triple.)


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## slow.climber (Nov 25, 2010)

Both Shimano and SRAM are now making 10 speed mountain bike cassettes.
For example, the Shimano CS-HG81 cassette is 11-36.

For little no extra charge, you could use a mountian bike cassette on your road bike. That would require replacing the road bike rear derailer with a mountain bike derailer.

The compact double with a mountain bike cassette would give you as much or more range than the triple with the 11-27..


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## AndrwSwitch (May 28, 2009)

On a road bike, I'd rather have somewhat tighter ratios, as with a 12-27 and a triple crank, than a MTB cassette to get the same low ratios. If I'm working hard, I get pretty sensitive to cadence.

I'm also a fan of buying a bike that already does what I want it to - so, for me, buying a bike in order to replace the cassette and rear derailleur, when for little or no cost difference I could have one with the right gearing in the first place, doesn't make a lot of sense.

For the sake of disclosure, though, I'm planning to do something along those lines to my 'cross bike if/when I decide I can spend the money on it. 

Anyway, I'm thankful for my triple crank fairly often, and I'm a little guy with a decent power output. I just like to have the choice of attacking a hill however I want to.


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## slow.climber (Nov 25, 2010)

Swapping a cassette and a derailer is very simple stuff.

We all know that we need to customize the fit of the bike. Customizing the gearing is equally important. 

The double/triple debate will never die.

Some people want doubles because there's less mass, and may people believe that there's less to go wrong, and less adjusting.

Bottom line should be to make your bike fit your needs and try to keep the mechanics simple..


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## PJ352 (Dec 5, 2007)

slow.climber said:


> Swapping a cassette and a derailer is very simple stuff.
> 
> We all know that we need to customize the fit of the bike. Customizing the gearing is equally important.
> 
> ...


JMO, but given that the OP has offered that he lives in central VT which has 'plenty of hills', has a Trek 2100 triple and rode about 1,200 miles last season, I think your option is a little extreme. If he were relocating to the Colorado Rockies, then _maybe_.


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## wim (Feb 28, 2005)

PJ352 said:


> If he were relocating to the Colorado Rockies, then _maybe_.


Obviously, it depends on your exact ride route, but central Vermont could throw steeper hills at you (and more often) than the Colorado Rockies. My vote is for the triple. But I've always liked triples a lot, and I wouldn't be caught dead riding a road bike with a 36 rear cog.


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## PJ352 (Dec 5, 2007)

wim said:


> *Obviously, it depends on your exact ride route, but central Vermont could throw steeper hills at you (and more often) than the Colorado Rockies. *My vote is for the triple. But I've always liked triples a lot, and I wouldn't be caught dead riding a road bike with a 36 rear cog.


Point taken, but when someone uses the word 'hills', I don't think of mountain passes.  

My point (in retrospect, poorly made) was that the OP isn't a noob, is familiar with his terrain and has (IMO) put enough saddle time in on his current (triple equipped) road bike to be at least generally familiar with his gearing requirements. That given, it seems a bit extreme to consider a 36T cog, but that's JMO.


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## wim (Feb 28, 2005)

PJ352 said:


> Point taken, but when someone uses the word 'hills', I don't think of mountain passes.


Understand. My comment was more about Vermont topography and backroads than gearing.


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## Hank Stamper (Sep 9, 2009)

Have a look at the link below and first plug in your current set up they compare it to the options you'rer choosing from and see if the difference you get is better, worse or indifferent to what you're used to. You'll have to ask the shop what the rear gears are and figure out what's on the rear of your current bike.
http://www.sheldonbrown.com/gears/

Focus on what you get at the easy end of the gears because as a non racer anything you buy will give you enough on the top end especially with how steep the hills are in Central Vermont where regardless of your gears down hill means steep and you're better off tucking than getting more out of pedaling anyway.

Good luck. Who knows what would be best for a stranger on the internet but I will say the triple is the 'safe choice' for someone who's not sure because although it might not be perfect there's very little chance it won't have all the gears you need somewhere on it. 
I've ridden in Vermont quite a bit and man are some of those hills steep. From the tone of your post I think you'd benefit from the extra low end on the triple (as would a lot of people not willing to admit it would help them). I'm only guessing this is the case but keep in mind as you get responses that a lot of people who have never been to Vermont probably don't totally grasp how steep the roads can be there.


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## lcecere (Dec 19, 2009)

Thanks all for the input.

And yes VT is not flat. I was on a vacation a couple years ago in MN and really enjoyed how far I rode, the miles looked great.

The LBS has both set ups and I'm thinking I will try both. But it does seem logical to stay with the triple as with kids and work schedule and weather (first 50degree day today and still snow on the lawns) in the near term I don't see my riding changing.

Thanks
Lou


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## slow.climber (Nov 25, 2010)

PJ352 said:


> ...That given, it seems a bit extreme to consider a 36T cog, but that's JMO.


IIRC, 32T and 34T are also available.

11-36 is the extreme. Few people will want that but it's probably reasonable for some of us old folks, especially those of us with bad joints.

Configure your bike to serve your body's needs. There's no shame in moding your bike in order to keep yourself active.

Around here, there are people long past retirement age still hitting the hills on road bikes but they're not pushing 11-21 cassettes.

Why give up your road bike because of the kind of cassette you're using?

Unless we get hit by a truck, we're all going to face the issue of our bodies getting too worn down to keep riding the hills (or anything at all). The longer you can keep going, the better your health will be.


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## charlox5 (Jan 31, 2011)

as someone who has moved from a 50/39/30 + 12/27 triple to a 50/34 + 11-32 double, I much prefer the double. My local rides are climb intensive and the 50/34 with the 11-32 gives me more low-end (and better top end) and the difference in the jumps isn't noticeable. 

on top of that, the double setup is lighter, and easier to tune and keep tuned. i don't regret it.


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## Drew Eckhardt (Nov 11, 2009)

charlox5 said:


> as someone who has moved from a 50/39/30 + 12/27 triple to a 50/34 + 11-32 double, I much prefer the double. My local rides are climb intensive and the 50/34 with the 11-32 gives me more low-end (and better top end) and the difference in the jumps isn't noticeable.
> 
> on top of that, the double setup is lighter, and easier to tune and keep tuned. i don't regret it.


I moved from a 50-40-30x13-14-15-16-17-18-19-21 triple to 50-34x13-14-15-16-17-18-19-21-23 double because "two are better than three" and 34x23 is the same low gear I was happy with.

It's not as good. Apart from the fully cross-chained combinations only 50x21 and 34x14 are the only overlapping gears on the rings, so in the wrong hill/wind/fatigue combinations there's a lot of double shifting which involves two right shifter wiggles going to the small ring instead of one since the next gear is 5 cogs away instead of 3. There's more chain noise too since I'm riding 34x14 or 50x21 near the ends of the cassette instead of 40x17 in the middle.

While a wider cassette would reduce the double shifting, then I'd miss my 18 and perhaps 16 cogs.

The 100 grams of weight saved only make me .1% faster up the steepest hills which just doesn't matter. It's no harder to keep adjusted (the derailleurs get adjusted when I replace the cables) and doesn't shift as well (perhaps because there's 16 teeth between rings instead of 10).


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