jgjulio

OK I have been looking at the new Specialized 2011 Roubaix Elite Sram Apex bike.
It has a compact crank with front rings of 50/39 with a rear cassette of 11-32.

I am used to riding a 30/39/50 with a cassette of 12-27.

Then new Roubaixs will not have a triple in the Elite model I am told.

I am 67 years old, weight 250lbs (losing slowly and aging fast).

I currently never use the big front ring and will use the small front ring on the 30/39/50.

I am told by the bike shop guys (several stores) that I would be happy with the compact crank and not miss the small front chain ring.

My worry is that all these guys talking to me are young and thin.

What do other Clyde's think?

Brontide

At your lowest gearing in each.

30/27 = 1.111 ( tire revolutions per crank )
39/32 = 1.218 ( tire revolutions per crank )

The double will be about 10% harder in it's lowest gearing over the triple. You have to decide if you will be 10% more efficient either now or in the near future. Be careful with other doubles, many don't have such a forgiving 32 on the cassette.

Brontide

If you are going to drop that kind of money anyways, maybe see if they can swap the 39 for a 34, that way your lowest gearing will be less work than your current triple and you can always have them put the 39 back on once you're in a little better shape.

FrenchFit 

Agree with the gearing post, but realize that your 39 is going to have an impact on your ENTIRE cassette, so ask yourself how many useful gears you'll are giving up by losing the 30. It's likely your 32 breaks down to something like 32-28-26- so you may be comparing apples and oranges by focusing just on the bail-out gear. I recently dumped my 50-34 compact double for a triple and have a lot more confidence in tackling big hills.

chasmm

I was in a similar situation this past Spring, although I had the triple option. I went from a Raleigh hybrid with a triple to a Roubaix Elite and I had to choose between the compact and the triple version. I also wasn't sure if the compact would be "right" for me. Background? I'm 50, weight was 280 (down to 260 now), and had just starting riding again last winter after 15+ years off the bike. My solution?

I figured out the lowest gearing that I would have on the compact version, and then went for some of my usual rides on my hybrid, forcing myself to only use gearing that was equal to or greater than that I would have on the compact. I also rode some of the more challenging local hills with the same self-imposed rule to see if I could handle them. I quickly found that I really needed the triple. I know the argument to HTFU, and it's possible that I would have gotten to the point where I wouldn't need the gearing that the triple provides, but...

And now, having the triple on the Roubaix means that I can ride just about any hill (locally that is...I still suck at climbing). If I didn't have the triple, there might be more walking on some of my rides.

And I guess that as I get better, I might wish that I had the compact, but that's the future.

Good luck with whatever you decide. I'm sure you'll love the Roubaix!

sstorkel

A compact crank is usually 50/34 not 50/39. Apex comes as a 53/39 standard, 50/34 compact or 48/34 compact.

I went from a 52/39/30 triple crank and 12-27 cassette to a 50/34 compact crank and 11-28 cassette. Honestly, I couldn't tell much difference in the lowest gear: anything I could climb with the triple I could also climb with the compact. The biggest difference, at least initially, was that the compact required slightly more shifting with the front derailleur. With the triple, I just left it on the 39-tooth chainring most of the time. Had to get a little stronger before I could consistently leave the compact on the 50-tooth ring. I still tend to cross-chain the compact more than a triple, though.

jgjulio

sstorkel you are right. I had the wrong information = the new Roubaix has the 50/34 with an 11-32 cassette.
This makes it closer to what I have now right?
I don't understand gearing and ratios well.
How much difference is there between the 50/34 with 11-32 and the 50/39/50 with a 12-27 cassette?
Thanks

canopus 

Not much.

Learn this:
https://www.sheldonbrown.com/gears/

dscheidt

I find this calculator more useful than Sheldon's.
https://home.earthlink.net/~mike.sherman/shift.html

Mr. Beanz

50?....

34/32 will give you 29 gear inches.
30/27 equals 30 gear inches.....so the other combo is actually lower.

MNRon

I converted my wife's Synapse from a triple with 12-27 cogs to a compact with 11-34 cogs (50/34 chainrings) and she loves it. She doesn't worry about cross-chaining and doesn't have to think about the gears as much.

canopus 

This probably works good for how gears are thought of today but for calculating a Half-Step setup or printing it out to place on the bike I still like Sheldons. However this is easier to use since it gives you everything after the calculate instead of going back and selecting your output like on Sheldon's.

Thanks for the link.

jonathanb715

I went from a triple to a compact double. The bike shop is correct - the overall gearing range with a wide range cassette for the compact is similar to a triple with a 12-27.

What I miss is being able to stick it in the middle chain ring and use that for most rides I did. I only shifted in the front for long and/or steep climbs and long descents. With a compact, the big chain ring will do some of that for you, but somewhere around 15 - 18mph (depending on your cadence and the gearing), you will find yourself needing to shift up front a lot. Whether that's a big deal seems to be a matter of preference - I was annoyed with it at first, but got used to it. To get around that, lots of people with compacts will cross chain a lot. I'd rather shift, personally.

JB

jgjulio

Thank you for the replys guys...
Next step is to go to my LBS and ride and see.

I talked to one of my favorite LBS's and they have 2009 and 2010 Roubaix's in and are willing to make me a very good deal.
What I am wondering if taking a compact Roubaix with a 50/34 and putting on an 11-32 cassette would make sense. Wouldn't that be the same as the Apex?

bradtx

jgjulio, With the advent of 9 and 10 speed cassettes and better engineered crankset tooth count, the compact crankset has become a viable alternative to a triple through out the gear range, not just top or bottom gear.

In '96 my first compact had 46-36 chainrings and IIRC a 13-24 7S. There were many times I just couldn't match cadenance with load so I completely rebuilt it with a 600 group and wheelset... fast forward to knee injury. Searching for a more knee favorable set up I looked at compacts of the time and the problem was the same, gear inches not much different from that bike's OEM set up. I threw on a 105 8S NOS triple group with a 52-42-30 crankset and all's been good with a 12-24 cassette.

I think most that are against a compact crankset may have had a similar experiance with the early designs.

Brad

meanwhile

Physiologically it's worse than that. Climbing is the result of the surplus force after that required to overcome gravity is subtracted.

However, the OP does NOT have to take the bike with the stock gearing! A competent store would have offered to put two different chainrings on; 48/34 could be about right. (You can't fit a 30 to a two ringer.)

sstorkel

Most road bike rear derailleurs can't handle cogs larger than 27- or 28-teeth. That's one of the reasons SRAM created Apex in the first place... But there's not a whole lot of difference between 11-28 and 11-32 cassettes anyway. For me, the hassle of converting to 11-32 wouldn't be worth it. If I were you, I wouldn't think twice about buying a 2009 or 2010 with a compact crank. Play with the gearing charts and you'll see that there isn't a whole lot of difference between a triple, Apex w/11-32 and a normal compact w/11-28.

meanwhile

A smaller interval may change better. Don't go for the 50 unless you think you need it.

jonathanb715

Apex is available with that gearing, but you can also get that with Rival (it is available with a medium cage derailleur now also) or a Shimano driveline (although you'd probably have to put on a mountainbike derailleur to make it work).

I have a bike that has a full Rival group, but I just substituted an Apex RD and put on an 11-32 - the shifting seems to be just as good as the Rival RD, and the extra teeth should come in handy on my next planned ride.

JB


Edit - if you really wanted to go crazy, you could get one of these and put on whatever chainrings you want (or stick with the stock 46-30).

Wogster

I don't understand the lots more front shifting on doubles, you have low range for uphill and flats (with wind), high range for flats (no wind) and downhill, with a double instead of losing 2 gears on each end, you lose only one. If you really need to do a lot of shifting, then maybe you have the wrong cassette on there. Which I think is a large part of the problem in general. Cassettes are still marketed as if we had 5 speed freewheels where you choose which 5 cogs you want and need to have knowledge of which cogs are best, this is why today we still refer to gear inches as if that explains it all. I think it would be better to have different cassettes based on the crank size and riding style, to give you a reasonable gear range for different uses.

Zudnik

My vote is to let the stores convince you by them allowing you to thoroughly test ride. I would not buy a bike from a shop that won't work with me in that situation.

Even when you lose weight, and I know this will sound bad, but as you get older, things are going to get tougher. So make sure you're not letting them talk you into anything. You need to be 100% comfortable with what you're paying for.

Good luck.

jonathanb715

With my original cassette (a SRAM 12-26), I could go down to about 12 mph in the big ring at a reasonable cadence - but I'm cross chained. To avoid using the biggest 3 cogs and maintain 80 rpm I'd have to be going between 16 and 17 mph. So, anything slower than 16 mph or so and I'd either be spinning below 80 rpm or cross chained. On the other hand, in the small ring @80 rpm at around 16mph andI'd be in one of the 3 smallest cogs (which is a worse cross chain condition, IMO - at least it makes more noise, and the SRAM shifters only have trim on the large ring).

No matter how you slice it, if you are cruising along between 15 and 17 mph with that cassette and a compact, and you're maintaining a cadence of around 80 rpm, you'll either be cross chained or shifting a lot. I prefer to shiift a lot rather than be cross chained.

FWIW with the new 11-32 cassette, the wider gaps actually work better for me, giving me some options right in that hole. I've also been working the last 18 months on increasing my cadence, getting comfortable spinning at 90 - 100 rpm for long periods of time, which has increased the speeds I'm riding at and reduced my dependence on finding just the *right* gear. However, I'm not the first person to complain about a hole in the gearing with a compact at those kinds of speeds.

I think part of the issue too is that you and I have a different definition of cross chaining. Not saying mine's correct, but I have to believe that bending the chain at the kind of an angle just isn't doing it any favors - although I'll be the first to admit that my choice of not using the 3 biggest cogs with the big ring is arbitrary at best.

JB

Wogster

I/m having trouble visualizing that big a cross chaining problem on a double, the gap between the rings should be about double that between cassette cogs, so if the big ring lines up to the 6th cog, the small one lines up to the 4th cog or there abouts on a triple they should pretty much line up to 3-5-7 meaning that cross chaining should only be an issue on maybe one cog on a double, two on a triple, otherwise you lose too many gears if you lose 3 on the bottom and 3 on the top then on a double where there are 18 speeds, your little better off then the 12 speed double on my Raleigh....

dscheidt

The point of a compact double is that there's only a small overlap between the two chainrings. With a 12-27 10 speed cassette and a 50/34 crank, you've got from 33 gear inches to 110 gi. there are only three cogs on the 50 chain ring that overlap with ratios available with the 34. Of those six gears, four (the extreme cross chained ones) are unusable. The lowest usable gear in the 50 tooth ring is about 63 gear inches, which works out to about 15 mph at 80 rpm. The tallest usable gear in the small ring is about 64 gear inches.

While the number of gears actually usable in a 2X10 setup isn't as much bigger then a 2x6 or 2x7, they're better spaced at both ends of the range. I don't actually think compact doubles make sense for non-racers, but that's a different problem.

It's likely the double on your 2X6 Raleigh is something like a 52/42 or 52/40. That's a much smaller difference, and there's a lot more overlap in gears.

XR2

To take a slight side step here. What detriments does cross chaining have? I am a cash restricted individual at this time. My bike is geared 52/42 with a 12-28 freewheel. Many times the best combo for me is 52/28. I'm not in the greastest of shape so I use it. I'd love to regear but finances are barely keeping my head above water. So is it really that bad?