new crankset--flexibility?
 

I'm riding a double crankset right now on a bike I inherited. 52/39 shimano 600 (precursor to ultegra).

Or should I say it's riding me. In the process of getting in shape and building strength back, I'm having a hard time on even mild hills.

I'm considering either:

a compact double crankset (like 50/34)

or a triple.

without opening a can of worms on virtues of double vs. triple (not interested) I would like to know if there is any compatibility with my cassette and derailleurs that I'd have to consider when deciding. I'm thinking I need to stick with a double crankset if I don't want to change anything else.

true?

With a triple crankset,you need a triple FD. A long cage RD is an option,you don't need if you stay out of the small cogs when in the granny ring. How about a cheaper option of a bigger cog cassette,depending on what you now have?

Is that a cheaper option? and so the reverse relationship is in the cassette? bigger cog=easier gear in cassette? sorry to be dense.

Bigger gears in the back makes for an 'easier' ride, where as bigger gears in the front makes for a 'harder' ride.

What type of rear derailleur do you have (shimano 600, I'm guessing)? Most can accept pretty big cogs in the back, but some have limitations. It would probably be easiest and cheapest to get a cassette (or is this a freewheel machine?) with bigger cogs. You can also just replace chainrings (instead of the whole crankset), again with the limitation that some FDs only accept a certain range of sizes.

peace,
sam

shimano 600 rear derailleur. the cassette has 8 gears 23-12. says 'hyperglide' on the outer edge.

sounds like a trip to my LBS is in order. I remember, when I got this bike overhauled, that there might be some issues with the capability of shimano 600 vs. available current cassettes.

I think the shimano 600 rear derailleur is rated to a 28t rear, though you can usually get a 30t into there. If you went to a 12-28 or 12-30 cassette, you'd widen your ratios a bit, but you'd get a 'lower low' gear, at only the cost of a cassette.

In fact, for 20$, nashbar sells a 12-28 cassette: http://www.nashbar.com/profile.cfm?c...eid=&pagename=

Ignore the 'ATB' name, a cassette is a cassette, and its only the ranges and ratios and marketing that differentiate between road and mtb. Its hyperglide compatible, and would likely bolt right on. The only adjustment you may need to make is the B tension screw, to move the jockey pulley down a bit farther to make room for the larger cog.

peace,
sam

The big trick is figureing out what gears you need. That's a question that only you can answer. It doesn't matter one bit what gears Lance uses, what I use, or what your local racer/bike mechanic uses.

Once you do that, take an hour to plot out the gearing combinations of all of the equipment options that you've been considering. A little bit of cost/benefit analysis and the question answers itself. Until you figure out what gears you need you're just spending money hopeing to stumble onto the right combination.

I recommend using Sheldon Brown's gear calculator to find out what you have now, and help you figure out what you might want, and how changes will affect your gearing.

Right now your effective lowest gear (small ring on the front and big in the back) is about 45 gear inches (which is a measurement that takes into account the front gear, the rear gear, and the size of your wheel, and is equivalent to the size of hi-wheeler wheel that would go the same distance per pedal stroke as your bike in that gear). 45 gear inches isn't all that low, if you do a lot of climbing.

A 12-28 cassette would bring your lowest gear down to about 37 gear inches, which is a big change.

Adding a 30t chainring and making your ride a triple would lower your lowest gear to 34 inches, which is barely lower than a cassette change, and would involve the expense of a new shifter, and possibly derailleur.

However, if you can find a 12-30 or 13-30 cassette, you could bring your lowest gear to 34 inches (just like the 30t crankset), but for only the cost of a cassette! Those cassette ranges aren't as common, but they ARE available. Remember that a 13-30 would lower your highest gear a bit too, but it sounds like you aren't as concerned with your highest gears as you are with your lowest.

Anyway. I'd recommend playing with the gear calculator to figure out how changes will affect your gearing. I think you will still find that a differently ranged cassette will give you the most change for the least money. If you need to make major changes to your gearing you could go to a different crankset, but you start the 'cascade effect' which can cause you to have to replace quite a few parts to get everything working again.

good luck!

peace,
sam

Thanks much for all of the input. It is very helpful and makes alot of sense. I learned something today..woohoo.

Now I just need to do some more riding in the meantime.

One more question:

Best places to start looking for cassettes?

actually, one other question. where can i find out what cassettes are compatible with my rear derailleur...it is rd-6401. looked it up...it was from 92-97. current 8-speed cassette. is there a way to find out if a 30t ring will fit? will it cost a bunch to get a dealer to install new cassette and do shifter adjustment?

Best place to go for a cassette would be your local bike shop, especially if they're going to be installing it for you. You're not going to find unreasonably cheap prices at your LBS, but you're not going to find much service, advice, or help with installation at an online store either. Which would you rather have?

In this case, I'd recommend your LBS. A wear item like a cassette won't be that much cheaper elsewhere, and you'll get valuable advice.

I'm having a hard time finding a reference for it, but I'm fairly certain that your RD will take up to a 28t, and likely a 30t. Your LBS should be able to find out for sure, and in the very least, slap something on and see if the B tension screw can be adjusted far enough out to work.

peace,
sam

Thanks Phidauex. I'm going to take all the advice here and go to my LBS with it. I did find the reference to the RD taking 28T. It is rated for that. The 30T they'll have to try out at the shop, as you said. I'm wondering if the difference between 28T and 30T is worth the effort to even check it out at this point.