Trek Lexa SL bike: compact or triple crank?

Curious, why do they make road bikes with the triple crank then? My local bike shop says most of the road bikes they sell are triple crank in our area.
Not disagreeing with the previous poster, just would like more feedback.

Because most bike purchases aren't to wacko's like us.

ride one.  then give me your opinion. 

 

they're for:

1.  mountain bikes, or if on a road bike

2.  people who aren't fitness buffs/ training and racing

 

If you really need a granny gear, either due to your strength/weight ratio or if there are really steep hills in your area, then hey, it makes sense.  but if you can at all push a 50/34 chainring, then I'd recommend sticking with just 2.  it's just more complicated to worry about 3 chainrings when shifting.  It's just intensely more convenient to be able to do it all with 2 chainrings than 3. 

Edited by morey000 2013-07-15 9:43 PM

So if I've been "training" on my mountain bike against a head wind and up steep hills, then I'd probably be okay on a road bike with the compact gears, right?

Correct. You should be just fine with a 50/34 and something like a 12-28 cassette. The Rocky's are indeed hilly (!) and there's some steep climbs, but that should give you more than enough gearing to get up pretty much anything.

In addition, generally bike companies put triples on bikes with fewer speed cassettes. IOW, triples routinely come on an 8 speed bike vs. 10 speed with a compact. It's a cost saving move and geared towards recreational riders vs. athletes. You can definitely get by with the triple, I have one on my cheap roady I built but honestly I hate it because you are always trying to find the right gear between the 42 and 52 front. If possible, go for thecompact with appropriate rear cassette.

I'd think that a compact with a decent cassette should be good for most anything you'll encounter.  Triples are just far more complex and difficult to maintain then their worth (IMHO).

I started the same as you... two sprint tri on a really old, really heavy mountain bike before I was ready to spring for a roadie. I bought a 2010 Lexa SLX with triple x10. Where I live it is very steep short hills and I was a new rider. I trusted my fitter with what suited my needs. After 18 months of riding, I bought a tri bike with a compact double. I could not have ridden this bike up the biggest hills when I first started - glad I started with the granny gears and improved my strength. I wanted to offer you a perspective on this from a beginner woman rather than an experienced man. I love, love, love my tri bike. I would not have if I had bought it first. Yes, the triple is mechanically more complex. I did not have any problems with shifting and I needed the extra gearing help at that time.

Sounds like utter snobbery to me to denigrate anyone for wanting to choose a triple rather than a compact.

While you can choose to go for a wider range cassette, there are pretty good reasons (i.e maintaining cadence!) why you might want to go for as close ratios on the cassette as you can. Having a triple chainring means you can do that while still having the option of going into tiny gears for steep hills.

As far as mechanical complexity is concerned, the difference is minimal; you still need to get the cable tension right, and you need the end-stops to be right irrespective of whether you've got a triple or a compact. The only big difference is in the shifter and you shouldn't really have to do much in the way of maintenance on those anyway.

You could take a look here.. http://www.machars.net/bikecalc.htm..and put in the ratios you're interested in. What I noticed, with the ratios on my wife's new triple (50/39/30 - 12/13/14/15/17/19/21/24/27/30) is that, let's say you're riding along in your 50x15 at 80rpm at 20.9mph and hit a hill. Drop the front cog on the triple (to 39x15) and you need to get up to about 100rpm to keep up speed for the moment. On the compact dropping the front would take you to 34x15 and 110rpm. To me that difference of 10rpm is significant. If you look at it from the point of view of the drop in speed for the same cadence you're looking at 4.6mph (triple) as opposed to 6.7mph. That's just an example obviously, and you may be unlikely to work your gears that way but, at some point I'm guessing you will be shifting the front and then the back (or vice versa) as opposed to trying to shift both at the exact same moment!

FWIW though I've recently bought a road bike with a compact on it (Felt Z95, front 50/34 and rear 11-32) and I've found that there are a couple of hills where, on my old hybrid (48/38/28 - 14-28) I ended up in the easiest gear, I can do on the road bike in the 2nd easiest gear so you may be fine with a compact if you've been training on a mountain bike.

At the end of the day It's horses for courses as they say. "Annoying to deal with and shift" is very subjective; you might not feel that way, especially initially, so the best piece of advice anyone can give you here is to try them both out and see what feels best to you.

Hope this helps (although I suspect it may be too late :-)

John

I don't think it snobbery at all. From a mechanical engineering point of view, it's significantly more complex to get 3 rings to shift equally well than 2 rings to shift well. That doesn't mean that you can't get a triple to shift satisfactory. Higher quality chainrings, higher quality chains (especially the chain gets to be more important as you work with more extreme angles with a triple), and a stiff bottom bracket will all help the shifting. Basically, if you your LBS sets the bike up for you (or you have the skills to do it yourself) and you're willing to spend a little more time and effort maintaining the bike, you can get a triple to work quite well. A compact is a little more forgiving though, so if you know that you tend to skip maintenance once in a while, then you may want to stick with a compact. You can get pretty low gearing with a 50/34 and a suitable cassette (just keep in mind that all rear derailleurs will have a max capacity, which is calculated by the difference between the largest chainring and the smallest plus the difference between the largest cog and the smallest cog of the cassette, ex. 50-34 gives you a difference of 16, 12-25 cassette gives you a difference of 13, so total capacity needed would be 29, which is within the capacity of most short derailleurs, if you wanted to use something like a 12-32 cassette, giving you a difference of 20 for a total capacity of 36, then you will need a long cage derailleur to take up the slack of the chain)

If you feel that a triple is the best choice for you and the terrain you ride, then by all means, use a triple. I don't think anyone should see that as a negative, but rather as a smart choice.

Edited by audiojan 2013-10-03 6:29 AM