eric von zipper

say i have a ultegra triple crankset (30/42/52), is it possible to switch those chainrings out for something more geared towards touring (24,38.48) or is life not that simple?

cyccommute 

The outer rings on an ultegra are 130mm bolt diameter (BCD). As long as the replacement rings have that diameter and the same number of bolt holes as arms, it's easy to change them. Finding them is another matter altogether. Try Loose Screw.

The inner ring should be a 74mm BCD (I think) and should be easy to change as well.

Personally, I don't like the 130mm/74mm BCD that much. I'd prefer a 110/74 BCD. The gap between the middle ring and the innner ring on the 130/74 is large and you can get the chain trapped in between them. It's a bugger to get out especially since it happens just as you are trying to climb some giant hill

Frith

As cyccommute mentioned above you're limited by the bcd. The lowest that ultegra will take is probably 50-38-24 which isn't that bad at all.

Revtor

and besides what your crankset bolt circle will take, you have to check what the ultimate range is for your front derailleur...
~Steve

cyccommute 

I haven't had any problems finding a 48 for the top end. With an 11 tooth cog on the rear cluster that's still a tall gear. My first touring bike had a 52/40/24 but I used a 14-34 rear freewheel too. Would almost prefer that.

eric von zipper

i was wondering about that, the cassette that is. i saw on the harris cyclery website that there are custom made cassettes: Cyclotouriste, but they are v. pricey. would having a 13/15/17/19/21/24/27/30/34 cassette (or something in that vain) and the 30/42/52 crankrings up front be ok for touring?

i need to learn about gear inches and ratios and that stuff...it's all alein to me right now.

cyccommute 

Sheldon Brown has already covered quite well here. Use his gear calculator and run the numbers. A 30 for the low on the crank is too high for my tastes. I also think that the jump from a 24 to a 42, while doable (probably) is too big. A 40 middle would be better but you would have to change 2 chainwheels as well as the cassette to get that. Chainrings run around $30 each and the cassette is about $100 for the custom one. Might just be easier to change the chainwheels and pocket the extra $70.

One note on the gear calculator: If you change a number on the gears you want to look at and just recalculate, it will add it to the results page. That way you will be able to compare all kinds of ratios.

bokes

I had (30/42/52) on my shimano 105 cranks with STI shifting and i installed some 'TA' chainrings 26/38/48 with an 11-27 cassette and now i'm a happy camper

bernmart

What was/is involved in making that change? I too have Shimano 105 but 30/42/52 and 12/27. I never yet have used 52/12, but could use some lower gears, esp. if I do loaded touring.

ncscott

Its pretty easy realy... An allen key and a chainring nut tool. If you plan on doing it more than once, buy the tool, or just have the shop do it. I've done it without the tool but wont recomend that for disclaimer reasons. You can get away with leaving the crankset on the bike but its much easier to take it off, in which case you need a crankset remover. Of cource if you take the crankset off, you will have to readjust the front derailer. If you can, then its easy... If you can't then pay the shop.
I've wondered for quite a while why people suggest to replace the whole crankset when the rings are repaceable. Any comments on that?
Scott

cyccommute 

With a 105 crank, you will probably have to take the crank off to change the inner ring. The BCD on the outer rings is 130 mm while the BCD on the inner ring is 74 mm, too small to work over the arms of the outer rings.

Sadaharu

I recently went from 52-42-30 on shimano rsx to 52-38-24 and that worked pretty well, once i worked out all of the wrinkles. I recently bought a 155 mm modified crankset from Mark Stonich that I am mondo thrilled about.

Anyways, when buying your chainrings, buy ramped if at all possible.

foggydew

As I have previously stated on these forums, I don't really tour at this time but hope to get back onto the long distance roads in the next year or two. However, when I was touring in the mid 90's for about six years of rather intense (my friends would say obsessed!) riding, a 1994 Cannondale T700 was essentailly the only bike I rode. The gearing that I had on this bike, after some tweaking) was:

44/34/20 chainrings and a 11-28 cassette.

It was great for touring in the mountains of BC, Alberta, Montana, Idaho and Washington. I'm sure the low gearing (.71 ratio) helped keep me injury free during that time period. And on the other end, I did a lot of no-load training on that bicycle including a few 200 and 300km brevets. The high end was fine for my style of riding which is by no means timid.

My recommendation - use the lowest, low gearing possible for touring.

blacktom

If you check out the discount mailorder stores (Nashbar, etc) you can find some cheap cranks, eg a 44/32/22 Truvativ (a cheap mountain bike crank) for $50. Chainrings will cost $25 to $40+ each. The Ultegra front changer can handle 22 teeth (52-30) so you should still be OK. And you will have some serious low gears without having to change the rear cassette. You may need a new bottom bracket but ask Nashbar.

Brian.