twowheelies

Can I change my DA 7700 53/39 crankset to the DA 7700 53/39/30, to get a little more help for my aging joints on those climbs? What mods would i have to make, any? Front derailleur? Wider bottom bracket maybe? Bike is a Bianchi San Lorenzo from early/mid 2000s.

Thanks as always for the help.

HTupolev

For a 53-39-30 triple, Dura Ace 7700 specified a triple-specific front derailleur (FD-7703) and triple-specific shifter (ST-7703 L). You wouldn't necessarily need to use those exact parts, but for indexed shifting on a triple, you'll want a front derailleur designed for road triples and you'll need a compatible triple-specific shifter to actuate it. You might be able to get your existing FD to work alright if you instead use a friction shifter.

Bottom bracket will depend on what's in there now and what crank you switch to...

Which rear derailleur do you have, and what cassette will you be using? If you have the short-cage RD-7700-SS instead of the RD-7700-GS, you might be pretty short on chain wrap with a wide-range triple.

tomtomtom123

Edit: oh nevermind, I found that your model has 130bcd so you are limited by how much smaller of chainring you can go.

I have 44/24 double, which is a 20t jump. If you don't want to change much except the chainring, you could simply swap the small inner chainring to the minimum of 33t assuming that you have 110 bcd. You may need to shim the chainrings to adjust the gap for optional shifting and chain rub depending on whether the thickness of the third party chainring is different from the original.

You would need a chain catcher too. Sram yaw fd include a catcher and don't need trimming. If you have a long pull shimano trigger then you could you'd set initially H index and then L index will have slack. I actually set to H trim and used the limit screw to make H index do nothing. If you have a short pull shimano trigger, I don't know if it has enough pull for Sram but you can search google to find out.

The increase of 6t means you need to check your chain wrap capacity to see if you need a longer rear derailleur.

rccardr 

You'll need to make a couple of changes:
1) New bottom bracket. That series has only two BB widths, double and triple. So, not hard to figure out which one you need, but might be hard to source it.
2) Front derailleur. Any 105/Ultegra/Dura Ace designed for use with a triple will work just fine. There seem to be lots of Ultegra ones out there on the used market right now.
3) Possibly rear derailleur. Carefully check the wrap specs on the parts you intend to use to see if your current RD will handle the change. I think it will, at least I'd try it first.
4) If you do have to get a new RD, the longer cage will necessitate a new and longer chain.

Honestly, if it were me, I'd buy one of the many used 80's Deore or Sugino 110/74 square taper cranksets out there and buy chainrings that suited my personal needs. Gives you MUCH more flexibility.
Square taper BB's are out there a-plenty. Your existing DA crankset and BB are very popular right now & should sell for a price that will make the swap virtually cost free.

Badger6

Do you really need a 53t big ring? You could swap in a Shimano 5700/6700 crank set with 52/36, or even 50/34, you'll need a whole crankset as opposed to just rings because your crankset is currently 130-bcd (bolt circle diameter), where the other ring sets I described are on 110-bcd. The advantage to going this route is you will get a lower gearing range (especially with a 50/34), and your current Bottom Bracket, FD and L Shifter will work just fine. You'll only need to adjust your FD to get the correct clearance over the rings, you may need a new shift cable, but that's an easy swap.

Iride01 

As others hinted, you might have an issue with your rear DR not being able to handle the difference between the big ring and small ring of a triple. That might leave your chain slack and dropping off the rings.

So if you are going to keep Dura Ace on it, you might get into an expensive change of 3 or 4 components, maybe more.

So what rear DR is it? What size cage, mid (GS) or short (SS)? What's the min and max rear tooth count?

And consider what Badger6 suggested. A 50/34 might do it. And there are smaller doubles too. That might be your less expensive route if a 2x will handle the range you need.

HillRider

A few comments:

1.The FC-770X cranks used Octalink V1 bottom brackets that came in two lengths. A 109.5mm spindle was used with the double crank and a 118.5mm was used with the triple.
2. The FC-7703 triple crank had a 130mm BCD for the two outer chainrings and a 92mm BCD for the granny. The granny chainring was bolted to the middle chainring, not the crank spider and a 30T chainring is the smallest that will fit.
3. You will need a triple specific front derailleur. 7700 was a 9-speed group so a 9-speed fd would be ideal but a 10-speed fd will probably work too, particularly with a 10-speed chain.
4. Obviously you will need a triple-specific front shifter but it could be an Ultegra or 105 if you aren't too appearance conscious.
5. A longer cage (GS) rear derailleur would be ideal but a short cage will work if you adjust the chain to just allow big-big and avoid small-small.
6 A longer cage rear derailleur will have no effect on required chain length.

twowheelies

Ahhh, this may be the best solution - thanks for that, i didn't know a 50/34 existed that i could swap in. So i need one of these i think:





the only thing that is confusing me is the shaft... how does that go together with the bottom bracket?




I have had my current DA crankset completely apart, in order to lube that pesky DA 7700 bottom bracket (whole other thread), and the chainrings and left crank just attach directly to the BB... no shaft. How does that shaft integrate with the BB? Do i have the wrong part?

cxwrench

You obviously need the correct bottom bracket...the newer style that is just cups, and doesn't have an integrated axle.

Iride01 

If your current cranks are dura ace FC-7700, then those are octalink.

In the picture is hollowtech. Whether it is hollowtech or hollowtech II, I don't know. Is the model number and series still on the inside of the crank? Tiagra might be a clue, but I'm tired of doing the leg work.

Hollowtech BBs are inexpensive if you already own that crank.

twowheelies

Thanks, but i'm not totally clear on what you mean. Are you saying that if I keep my DA BB7700 - which is just cups, no axle - i can just leave that axle out? if that's the case, how does the left crank attach?

cxwrench

Iride01 explained it perfectly. Your D/A crank is Octalink. The axle is contained in the bottom bracket. It is what's known as a '3 piece crank'. 2 crank arms and a bottom bracket. The new crank you have pictured is Hollowtech. This system uses a bottom bracket that has no axle, the axle is attached to the Drive side crank arm and slides through the bottom bracket bearing cups and the left arm is bolted onto the end of the axle. They are NOT compatible in any way. If you want to use the newer crank pictured in your post #8 you need the correct bottom bracket. I've told you what it is, you can find it.

Iride01 

You'd have to get a different BB if you use a different type crank. BB's are cheap.

It'd help if you read the model and series number off the inside of the cranks instead of letting us just assume everything is DA 7700 on your bike.

HillRider

Not exactly. The FC-7700 crank uses an Octalink bottom bracket aka "Hollowtech" or "Hollowtech I". The current cranks with the spindle integrated into the drive-side crank arm are "Hollowtech II". The matching Hollowtech II bottom brackets are external cups and bearings only.

twowheelies

Ok - thanks for all of this guys. So basically, it comes down to Octalink/Hollowtech1 vs. Hollowtech 2, yes? Is one system generally considered preferable over the other? Will I have other compatibility issues if i switch to a hollowtech 2 crank set?

thanks again.

Inside of crank:

cxwrench

Octalink/Hollowtech 1 is pretty much obsolete. Do yourself a favor and go with the Hollowtech 2 crank and bottom bracket. It's been around much longer and shows no signs of being 'obsoleted' any time soon.

Badger6

Apologies for my error earlier, what I get for multitasking while I was waiting for my boss to review something and killing some time. Haste makes waste, they say...

The Hollowtech II is probably preferable, in that it is more modern. In good repair, both types will function identically as far as the rider is concerned. The biggest concern for compatibility, in terms of a conversion, is BB threading and width, but that bike should be BSA (English threaded, 68mm wide shell).

twowheelies

Thank you all once again for the very useful information, it is much appreciated.

And sorry to keep coming up with more questions, but at what point do I run into a 9-speed vs 10-speed compatibility issue, if i switch to an Octolink 2 crankset?

masi61

Let’s say you decided to convert your 7700/7703 crankarms to the 53/39/30 triple.

You would need the longer Octalink 118.5 spindle bottom bracket. Used ones pop up quite often on eBay and are full cartridge (unlike the adjustable, rebuildable 7700 one). New ones are around but getting more scarce and therefore more pricy.

A bigger obstacle would be in obtaining the 39 tooth middle chainring that has the ability to bolt the 30 tooth granny ring to it. This is more of a white unicorn. They may be completely unobtainable. You could try your LBS and see if they have an account with Euro/Asia imports in California but be prepared to pay up.

Another way to convert your 7700 arms to a triple is to source a Specialties TA 39 tooth “triplizer” chainring. These are a bit more obtainable for around $100 USD. If interested you could check some euro on-line sellers. XX-Cycle in France comes to mind. They might have that chainring. It would have the more common 74 bcd chainring bolt circle anyway which (as previously stated) permits use of more common 74 bcd granny rings that come in more sizes than just 30 tooth. You would have to be patient and locate some triple chainring bolts as well.

Octalink cranks and bottom brackets are definitely fussier than the modern Hollowtech ll stuff. If you wanted a triple there are still some NOS Ultegra 6603 or 6703’s that occasionally pop up on eBay but man, the COVID inspired bike parts shortage has made getting spares really challenging.

70sSanO

You can run a 9 speed system with a 10 speed crank.

John

masi61

Hollowtech ll (10 speed) chainrings are backward compatible with 9 speed. No problem at all with shifting precision as far as I can tell.

70sSanO

Here is my take on the it...

Research 10 speed compact cranks, read reviews, check a style that fits what you want; and is supported. As a side note, I went with 6503 over a 7703 triple crank solely of the spider system and the eventual issues with replacements.

Dura Ace 7703 derailleurs are very nice. I’m not sure how well a 7700 will shift with a compact, others can chime in. But having an FD-7703 is a plus.

If you foresee needing more chain wrap, it is something to consider; but there might be max cog concerns down the road. My road RD of choice for older drive trains is an XTR M900/910. Basically vintage Dura Ace on steroids.

John

twowheelies

Thanks for all the advice - much appreciated.

I actually upgraded to the DA 7800 derailleur a while ago and the bike shifts so nicely now that i am reluctant to mess with it - so i have decided to just leave it alone and get a newer used bike with lower gear ratio. I'll keep the Bianchi for flatter rides and use the new bike to the hills here in the Bronx and upper Manhattan.

thanks again for the guidance, i appreciate and respect all of your expertise.