Southern California - I am a Dork Part MCMVII - Compact Crank

So, I buy this bike off this guy that is just perfect for me except the gearing is a bit tall (I am old). I need to order a compact double crank and front derailleur. It is a clamp on so I dutifully grab my calipers and measure the downtube, BANG, right at 35mm, I place the order. The crank comes in a day before the derailleur. I install it and everything is great, in fact, the front shifts just fine, I am wondering why I even bought the compact specific derailleur. The next day the front derailleur arrives and I take off the old, clean the downtube real nice. Put on the new but oops, it is loose. I look inside the old derailleur, it says 32mm. The dang downtube tapers from 35mm on the top to 32 to the bottom. If I wasn’t so blind, I probably would have noticed. I put back on the standard derailleur, this time adjusting the height to the new chainring. The thing shifts flawlessly!! There is a 16 tooth spread (50-34) and the derailleur is rated for 15 teeth difference but there is no chain drag on the pin, not even close. So, it turns out, I really didn’t even need the CT derailleur.

Lessons learned
1. Measure the downtube at the point the derailleur will install, not just anywhere on the tube. Get over the fact that not everything is straight tube steel.
2. When going between compact and standard, try the existing derailleur. There is a good chance it will work fine.


So, concludes another chapter in my life.

Hey, if you're only a dork once in MCMVII, you're doing pretty good.

You're sure it wasn't MCMVII, pt. XXIII, subset CLXIV, para. XV, addendum II?

I have never heard of a "Compact specific front derailer".... Usually all that is needed to to adjust the height of the front derailer to be 1-3mm above the large chain ring.....

I guess you have now found that out :)

Also, which Compact did you get? Campy on the Bianchi?

Hey, if you're only a dork once in MCMVII, you're doing pretty good.

You're sure it wasn't MCMVII, pt. XXIII, subset CLVIX, para. XV, addendum II?


Ya know, I just threw some random roman numerals out there, really. So, it is #1907 from the epoch (which is my day of birth as everyone knows)


I have never heard of a "Compact specific front derailer".... Usually all that is needed to to adjust the height of the front derailer to be 1-3mm above the large chain ring.....

I guess you have now found that out :)

Ya ya, I think you are right. The CT does have a little different arc to match the smaller large ring and a bit taller inside to handle the larger range of rings. Turns out the old stuff works fine. This is what I get for reading specification sheets.

Also, which Compact did you get? Campy on the Bianchi?

ahhh yeah, even with all my faults, I wouldn't put Shimano on a Bianchi.

Anyway, it is a Chorus group.

Campy does sell compact specific FDs. The jury is out as to whether they are actually needed.

Jim, now that I think of it, I usually add some length or width (in error) to items I have measured in the past. I think it is one of those male specific tendencies.

Ya know, I just threw some random roman numerals out there, really. So, it is #1907 from the epoch (which is my day of birth as everyone knows)


And stupid me opted to ignore the C and actually thought you wrote MMVII, which is this year. Anyway, that was pretty good for throwing random Roman numerals out.

Jim, now that I think of it, I usually add some length or width (in error) to items I have measured in the past. I think it is one of those male specific tendencies.

I thought you just measured in centimeters instead of inches.

Campy does sell compact specific FDs. The jury is out as to whether they are actually needed.

I remember Cleave mentioning that I may need a new FD. I am thinking based on that statement that in some configurations (like mine) it works fine with a standard derailleur.

And stupid me opted to ignore the C and actually thought you wrote MMVII, which is this year. Anyway, that was pretty good for throwing random Roman numerals out.

When you mentioned it, I thought that it randomly came out as 2007 also. I was flipping thinking I was the next Uri Geller or something. Then I realized that C snuck in there.

:rolleyes: :rolleyes:
1. Measure the downtube at the point the derailleur will install, not just anywhere on the tube.

Mounting a front derailleur on the downtube??? No wonder it didn't work... Unless it's something new from Campy :rolleyes:

Jeff

:rolleyes: :rolleyes:

Mounting a front derailleur on the downtube??? No wonder it didn't work... Unless it's something new from Campy :rolleyes:

Jeff

Argh, I meant seat tube....gawk

So, I buy this bike off this guy that is just perfect for me except the gearing is a bit tall (I am old).

I'm curious...is the guy or the bike perfect for you?:D