using a triple crankset as a double: possible? advisable?
 

is it possible to use a triple crankset as a double without problems? a friend asked me this, and i wasn't too sure. The idea would be to switch the two larger rings from the triple to standard double rings - then take off the smallest ring. would there be any issue to be aware of with this set up (assuming the chainring BCD is the same for the new rings and I can get the front derailleur limit screws set up correctly).

Chainline would still suck. You would be better off buying a used double crankset.

Typically the triple crankset has a different width and therefore will throw off the front derauiller.

Is the person using a triple shifter or was this a double to start?

so smaller chainring (actual middle ring) and the large cogs on the the cassette would be the issue, hu? I forgot about that. hum.

she has a 9spd 105 triple shifter... is this double compatable? (i know the 10speed 105 ones are)

Hi 3373
I had a similar setup before I got my double and found that 1) the chain still jumped when shifting down to the smaller crank and you pushed too hard on the shifter. 2) The wear on the chain and cranks were higher as the mechanic had to ensure the chain was slightly shorter to ensure good tension on the system. FWIW if you can afford a proper double, even if it was second hand, then get it as the hassle of releasing a dropped chain from the space between the smaller chainring and the downtube/seatube/BB is something you don't want to deal with on a climb ... it can get real dirty with grease and gunk.
G'day and stay safe always.

thanks everyone. i'm going to recommend a double for my friend!

I would recommend buying a compact crank just because you get a bit more range in the gears =P

The FD shifter on my 105 ten-speed triple broke and I replaced it with a 105 double. I didn't know that the 105 STI came in a double-only configuration, but it does. And that's what I bought on Ebay. So, I removed the small chainring and ran it as a double. It worked fine. I mostly stayed on the 39, which I think lines up best with the cassette, so not much cross chaining even at the extremes. Now I'm using a standard double and I really like it. So I guess I'd recommend the double or compact approach, but I don't think your friend would have problems converting the trip to a double. At least I never did. And yes, I would get onto the big ring on descents; never dropped the chain.

I'm currently using a triple crank set up as a double and its not the problem people are making it out to be, BUT, you DO need to use a double BB NOT a triple BB. A triple BB (bottom bracket) is spaced at 113 mm or 118 mm and a double is spaced at 108 mm. Then the only possible issue is that the triple crank had the bosses to mount the inner ring sticking out a little so check that the frame is dimpled in that area to allow clearance.

If someone has the money to spend then fine, get another one but its not that big a problem really.

Anthony

How different would running just the two largest rings and stopping off the FD from running a double? I think it's just a matter of the triple's chain line being centered a few mm outboard compared to a double, which seems to work fine for those people that like/need a triple. Most people just use the small ring for the occasional steep climb and are in the outer two most of the time.

If you're going to buy new chain rings then you may as well go for a double as it will work out pretty similar in cost.