I am planning on changing my 5700 triple set-up to a compact double.
I don't want to change the shift levers if I don't have to.

Can I use the triple levers, using the two outer positions for the double? Both outer positions have trim options.

I've seen posts about doing this, and I think that I'll be OK.
Is the spacing the same on the double as it is on the triple?

Does anyone have step-by-step instructions, or tips on how to do this?

Thanks,

Peter

Double posting? See above for replies. I believe you can delete this duplicate.

I double posted by mistake.

Please post on the other thread

Peter

I recently did this with the 5700 double. The spacing is the same, just adjust your high and low limit screws so that you can't push the shifter past the small ring. I had to lower my front derailleur a little to get good shifting. You may need to switch bottom brackets as well. I thing the triple use a 118 BB and the double uses something closer to 108.

Since this is a duplicate posting you might try posting your comments on the other version.

I have two comments on this. First, it's necessary to use the two outer shifting positions to protect the internals of the brifter from an inadvertant shift to a locked out outer position. This is described in the other posting. Second, the 5700 cranks are Hollowtech II and have the bottom bracket spindle built in so you can't change the spacing.

I didn't mean to double post, I hit the back button by mistake when making an edit.

I only see one BB on Shimano's website, so from everything I see, I can use the same BB.
I just want to make sure that the spacing & FD travel will be the same for the double as it is for the triple.

Thanks,

Peter

Well, after complaining about the double posting, I'm still replying to this one too.

Anyway, yes, there is only one "bottom bracket" for this crank but in this case "bottom bracket" just means the external cups and bearings. It does not include the spindle which is permanantly attached to the drive side crank arm so you have no control over the chainline or crank position.

The double crank will sit slightly further inboard than the triple and you will, at a minimum, have to reset the inner and outer limit screws for your front derailleur. Your triple front derailleur may work adequately with the double or you may want to replace it with a specific double fd if the shifting isn't good enough. I'd try the existing fd first before spending the money on a new one.

Thanks,

I am planning on using a new FD, I was able to get the crank, RD & FD for under $240 on a special.

One thing that I noticed today on my ride is how the angle of my femur / hip is different, and greater on the drive side. My knee points outward more on the right than it does on the left. After my ride, I measured how far each crank arm is from the downtube. There is almost 1/2" difference, with the drive side being greater. This probably accounts for the hip / femur / knee angle, which could only lead to injuries.

Now, if I do need a new shifter, I'm looking at ~ $400 total. I might as well spend about double that (eBay ~$850) and buy an Ultegra 6700 group, and have a lighter, slightly better groupset that will save my knees & hips.

Any thoughts?

The difference in the angles of your femurs has more to do with your personal body alignment from your shoulders to your feet than the extra centimeter or so of spindle on the right side of your bike. Possible causes, from simplest to more complicated, are incorrect cleat alignment, incorrect foot support, foot injury, leg injury, hip injury, one leg longer than the other, scoliosis or other back abnormality. While I don't advise a professional fit session for everyone, I think in your case this would definitely be preferable to spending $850 on equipment and not getting any closer to solving your problem.

By the way, in the recent past many bikes with 5600 compact double drivetrains were shipped with 3-speed front shifters. We set up the shifters to operate on the two inner positions, locking out the third using the outer limit screw. With good setup the third position cannot be inadvertently engaged without breaking something.

Therein lies the problem. Using the two inner positions on a 5700 triple brifter and attempting to shift to the locked out outer position can indeed break something. Using the two outer positions and setting the inner limit screw to lockout the granny position only leads to a slack cable if you shift to the nonexistent third ring. It's a nuisance but not a mechanical hazard.

No problem.