cyclingshane73

So I decided pretty much this year I was going to swap out my triple ring 105 drivetrain for a double ring 105 set up. Despite my best attempts to try and trick the drivetrain into thinking that all was well just by changing the cranks was a lesson in frustration. The chains consistent protests by riding right off the inner ring onto my BB shell no matter how much I tweeked told me I was in trouble. This all despite everything I've read on this board and even the Shimano site, which pretty much says you'll have to swap out four components, I figured I could get away with it. So now as well as changing the rear derailluer and BB I await a front derailluer from my local LBS.

In a way I'm counting my blessings as I was seriously considering Ultegra cranks to upgrade to, (which I'm told there is not much of a difference except in weight, quicker shifting and price, but I'm not winning any races so...). Therefore I would have felt compelled to get the rest of the parts to match the cranks! Everyone hear knows my dilemma in that sense, I mean the grouppo just HAS to match!

So I'm pretty much commited now and will hopefully have a nice looking well shifting 105 double ring DT by tomorrow. If anyone can learn from this is that no matter how good a mechanic you think you are, there are somethings that just won't work!

*Note the shimano website says that my shifters will work with a double or triple set up. For that I am truely thankful. Whew!

Feltup

Why did you change? If your not a racer and worried about weight it is a waste of time and money IMHO. Plus have you ever been 20 miles out and bonked? Having that granny gear can be the difference between riding and walking.

Retro Grouch 

You can almost never change just one part on a bike. Almost always there's at least one other component that's affected.

cyclingshane73

Why? Because I wanted too and could.

I wanted a double ring set up as opposed to a triple anyway when I was initially shopping around. I was able to purchase the bike for a really good price so it got me going. I used the granny once and thought it was pretty useless from that point on. I pulled off several 100+k rides last year and never really had any problems with bonking. I just ate alot on the bike and kept the fluids topped up. But thanks for your concern.

The post is not meant to be taken too seriously. Its more of a hey look at me I'm an idiot. I seem to have an abundance of humility as I get older.

Peace.

Feltup

Bonking can happen to any rider. I ride 2 centuries(i don't use the granny) a month and it happened to me on a 40 mile lots of hills ride. I got to the turn around point and went to my bag to get a gel pack. Well I had forgotten to put one in. So I was in bad shape on the way back. I wasn't knocking you for going to a double I was just stating my opinion. What is funny is a couple days earlier I was talking about how useless the granny was. It is a good tool on a training bike.

uciflylow

I wouldn't mind going to a double set up myself, seeing how I'm on the "other" end of the state from Feltup. The main reason I would like to try one out, is the Q factor is a little narrower. I use to think that was a lot of bunk, but have noticed when I ride the mountian bike I perfer my feet closer. I personaly wouldn't go to the trouble of spending the extra bux on that, but the next bike I buy will have a double. If I need the lower gears I will just have to resort to a bigger back sprocket, but around here I just don't use my granny gears at all, that's with a 12-25 BTW.

I can also think of more bone headed things you could have spent that money on!

HarryK

Hey, I can relate to your post! While reading it, I was thinking how many times I've tried going cheap on a project, and then ended up doing it right the second time. Sounds like you had a good learning experience at any rate.

Feltup

Same here. I hope it will have a Litespeed decal on the side too.

Scooby Snax

Pssst. Shane, whatcha doin with the tripple cranks, are they 105?
I've actually come to the conclusion that I either have to swap out my rear cassette or, go for a tripple.

threadend

Are you saying that you can't set the travel limit screw to keep the chain from going off the inside ring? :confused:

jfmckenna

Yea that's what I was wondering? I did this very same thing to my old touring bike w/ Suntour XC front deraillure and Sugino Crank set. I took off the granny gear for CX racing. I set the limit screw and all was fine.

jeffpmills

Yes, when you change from triple to double you need to change EVERYTHING.

Front derailleur
Rear derailleur
Bottom bracket
Cranks
Chain

The BB for a triple is actually longer (pushes the entire crank set out) than a double. So, if you're riding double cranks on a triple BB, you're definitely going to have alignment issues. Also, the triple rear derailleur has a longer pulley arm to handle the increased range required to keep tension whether the chain is one the (very) small chain ring or big ring.

Also, the front derailleur is actually what houses the shift notching (which is why you can use STI shifters for both a double and triple derailleur), so that needs to be changed as well.

Sounds like you're on the right track. Changing drive trains is expensive and time consuming.

Jeffrey Miller

cyclingshane73

Just a final note to say that its all done. Everything now works flawlessly. I don't regret it even though I was hoping to get away with certain things. Oh well, live and learn.

Avalanche325

I know you are all done. You can use a triple rear derailuer on a double. It just has a longer cage.

I can't figure out why people will spend their last dime to get one more gear on the back, but don't want another chain ring on the front.

Not actually. It is still the shifter. There are four clicks. When using a double you have two positions for the small chain ring and two for the large. When using a triple, you have one for the small, two for the middle, and one for the large.

jeffpmills

Avalanche325

I stand corrected. Thank you. Just a couple more questions.

1. Does using a triple rear derailleur make it difficult to measure the proper chain length?

2. Yes, the shifter's are compatable with both, but isn't it still vital to use a triple front d. with a triple crank?

Jeffrey Miller

Phatman

hey, if I wanted to use a single chainring, could I buy a triple BB and put a double crank w/o the outer ring, and say, a 45 tooth ring on the inside ring...that would line it up with the middle of the cassette, right?

cyclingshane73

I can tell you right now just looking at my own set-up now that you would be better off to use a double ring BB instead of a triple one especially with Shimano components.

Avalanche325

jeffpmills,

The deraileur doesn't determine the chain length. It is the large chainring / largest cog combo. When you do the chain measurement this way you don't even route it through the deraileur. The deraileur just takes up the slack when moving to smaller cogs and chainrings. (as far as length goes) The Parktools website shows how to get it right.

Yes. The front der. must be changed. I think the cage is different.

Apparently the short cage rear der. shifts a bit crisper than the longer one. Nothing that I could notice though. I live near mountains and enjoy the climbs. I'll take more gears myself.

cyclingshane73

You are correct the cages are VERY different, the double ring one actually has a shorter cage with less "manipulation" or bends to the cage plates for shifting the chain around.

No mountians in TO. Although I do think I'm missing out on something there. Peace.

Somewhat off topic, which I learned the other day is you can actually by a band clamp for your seatpost for front derailluers which normally mount to a braze on. I thought this was kinda neat, because now if I switch up the frame to one with a braze on, I don't have to purchase a separate front derailluer. The LBS pointed this out to me. I did not know that you could do a set up like that. Pretty cool.

jeffpmills

Avalanche325,

Thanks, that Park Tools site is pretty handy!