Gearing: Road vs Hybrid

[HillSlugger]

Hi,

This is my first post but I've been lurking for a few weeks.

When I bought my hybrid bike a few years ago I envisioned doing a mix of road and trail riding. I've basically spent most of this time on a trainer stand in the basement. Now that I've finally come out into the sunlight I'm not doing anything but road rides. I've switched down to 28mm tires and it's made a huge difference, but I'm still contemplating trading in my hybrid for a flat bar road bike. I'm wondering if I could get the advantages of a road bike by swapping out my cogset. I currently have 28/38/48 and all the bikes I'm looking at have 30/42/52. If I make this swap the only major difference would be weight. As a cost-conscious gal, does this sound like a good idea? What are the pros and cons?

Many thanks, Nicole

[Cassandra_Cain]

Hi Nicole - glad to see you out in the open

Hmmm, my first serious bike was in fact a nifty little Trek Hybrid. Served me very well. I understand your want to change things up a bit.

The gearset you are thinking of, 30/42/52 is pretty standard in terms of road bikes - at least consumer grade ones. By switching out of your present gears, you'd get more potential top end speed while less of a granny gear, if you will, for real tough hill climbing.

Back to the hybrid thing, I've since moved on to a road bike and it is light years of difference. You start off with less weight, which gives you a big advantage in climbing, then you have more narrow tires, lighter wheels and components, which are more conducive to speed....finally, the riding position is more aerodynamic which again, helps potential speed in the flats.

I suspect if it is speed that you are really after, that a move to a road bike is going to be your best bet. That's what I ended up doing. I know it is a lot of money of course, so think it over, but that's just my experience.

[HillSlugger]

Speed is not what I'm really after but I do find that I top out on gears when going downhill. The 30/42/52 gearing would seem to give me better top end while not taking too big a hit in the granny gear.

Once the bike is moving, do I really get a big weight advantage going from around 32 pounds to around 22 pounds? How does geometry really affect things?

[SadieKate]

You may find that swapping your cassette for more of a "corncob" gives you better gearing. However, no matter what you do, you need to take the derailleurs and the chain length into consideration.

What is the tooth range on your cassette?

[mimitabby]

You may find that swapping your cassette for more of a "corncob" gives you better gearing. However, no matter what you do, you need to take the derailleurs and the chain length into consideration.

What is the tooth range on your cassette?

huh? why?
Please explain your statement.. still learning!

[Cassandra_Cain]

Speed isn't what you are after - ok well, that does clarify things.

a 52 big chainring vs a 48 would be an advantage going downhill - I imagine now you find yourself spinning quite a bit on steeper declines.

In that flats, the biggest factors in speed are aerodynamics (rider and bike) and power (rider obviously). So in that sense a roadbike would give you a more aerodynamic position which would help your speed (power remaining equal of course). Geometry affects aerodynamics and better aerodynamics are fairly important, in bike racing they spend mass amounts of money on improving that.

For climbing, weight and power are the big factors, usually expressed in power-to-weight ratio. Here aerodynamics would be secondary and it would just be the weight of your hybrid vs. that of a roadbike (say 10 pound difference). All other things being equal, a 5 kg reduction in weight, on say a 3% grade for 2000 meters distance approx 11-12 seconds.

[HillSlugger]

The cassette is 11-34t. What do I need to consider with the chain and derailleurs?

What's a "corncob"?

[SadieKate]

Your chain length is determined by the number of teeth from both the chain ring and the cassette (chain wrap). The cages on dérailleurs are different lengths (producing a different parallelogram or something or other) as they are critical for taking up the chain slack/tension as you move from one combo of gears to another.

The rear dérailleur cage for a large cassette is longer than that needed for a corn cob (a small, tightly spaced road cassette).

A front dérailleur also has a limited capacity for the number of teeth over which it will shift. The cage will actually be deeper for a triple crank.

Sheldon Brown probably has an entire epic dissertation on this subject -- especially now that compact cranks are the vogue and creating a whole new set of shifting challenges.

[kiwi girl]

What's a "corncob"?

I might not get this exactly right - but I'll have a go

'corncob' is used to describe road cassettes that generally have higher gearing and therefore because the cogs are smaller they have one tooth increments between cogs - just because of the way it looks

[DebW]

I think you would be better off swapping cassettes. Your current 11-34T means that the jumps between gears are large. Changing to, say, an 11-27 or 11-25 would mean your jumps between gears are smaller, and you can more readily find a gear that's right for the given conditions on the flats and gentle ups and downs. You should be able to go to a narrow-range cassette without changing the derailleur or chain (there will be more chain than necessary but the long derailleur cage can take up the slack). You could swap the derailleur to something intended for the narrower range and get a quicker shift if you want to. Swapping chainrings is a more expensive proposition and still leaves you with huge jumps between gears.

Regarding the high end, it used to be standard to have a 52-14 or 52-13. You've already got a higher gear than that with your 48-11. I have a 52-13 high gear on my road bike and only use it on the biggest downhills. In fact, I seldom crank that gear very much because I get more speed by dropping into a tuck and coasting. What cadence do you pedal at? Upping your cadence (to the 90-110 range) will let you use your gears more effectively.

[HillSlugger]

I was hoping this would be as simple as off with the old, on with the new, and ride off into the sunset. I think I must resign myself to plugging away with what I've got and hope my honey is feeling generous come christmas.