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my bike is Cube attain 2016: https://archiv.cube.eu/2016/776101

I upgrade the shifters to Tiagra 4700 and also the derailleurs and chain and the problem is front derailleur can not shift up. I found the front derailleur can not put the chain "out" enough.

I guess the problem is caused by wider BB of this bike (73 / 118 mm octolink BB). Any solution? Thanks in advance.

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    I thought that 118mm octalink spindles were for triple cranks. The linked bike specs say it’s a double crank, but I can’t determine the shell width. Can you confirm these specs are correct? Also, did you adjust the front derailleur’s high limit screw properly?
    – Weiwen Ng
    Dec 7 '21 at 0:02
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    Is it really 73mm? That is beyond unusual for a threaded shell road bike. If you move the FD manually (by hand), can it move far enough then? Dec 7 '21 at 0:39
  • Thx for your comments. I doubled checked the original BB it is 73x118 mm. I tried installed normal 105 crank before but it is not possible due to the axle length
    – Bill Chan
    Dec 7 '21 at 9:28
  • tried also the original Claris front derailleur, it can put the chain further but still can not shift up.
    – Bill Chan
    Dec 7 '21 at 9:30
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Assuming you mean that the front derailleur can't even get far enough if you force it by hand, and also assuming you've got the original cranks: FC-2450 gets to its correct 43.5mm chainline with a 113mm Octalink V2 spindle. Shimano's listed BB for them is BB-ES300 in 113, although any other 68x113 Octalink V2 would work. If you've got a 118 on there, that could be causing the problem - the chainline will be around 46mm, which no Shimano road groups use. You write that it has a 73x118 BB, which is curious - road bikes "never" have 73mm shells, or should. If that's indeed what you have, it sounds like something someone put in by accident.

Like the other long-armed Shimano front derailleurs, FD-4700 needs a lot of cable tension and also needs its "converter" set to the correct path (the little flippable thing by the cable anchor. Errors with either of those could result in the shifter not being able to move the FD out far enough, but you would still be able to force it over by hand.

Edit: I did some more research. This is indeed a rim-brake, 130mm-spaced road bike with a 73mm shell. That is truly an odd combination, basically an unequivocal mistake on the manufacturer's part, and it is going to present some challenges. I don't know what the maximum chainline the 4700-level Tiagra FDs can take are - Shimano simply lists 43.5 for the double and 45 for the triple. Since the limiting factor here is the chainline of the outer ring position and cranksets can vary a little in their ring-to-ring spacing, getting to a definitive answer in the abstract about what will work can be tricky when one is pushing the limit of an FD's reach.

If you're looking for a simple answer that doesn't have you buying a new crank, this is the first thing to do: measure the current chainline and the various potential interference spots that could arise if you were to move the crank in with a shorter spindle, like between the large ring and the chainstay. If you can make the chainline match the spec your new FD wants (43.5mm for FD-4700 or 45mm for FD-4703), it will probably just work. The probably is because the ring-to-ring gap being bigger than a 10-speed FD expects could theoretically throw it off, but it probably won't be enough to matter.

If the above didn't work with the crank you have, the remaining options all involve buying a new crank or changing the ring size, depending on what crank you have, which again we don't know.

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    Would a GRX front derailleur help if it really was a 73mm shell?
    – MaplePanda
    Dec 7 '21 at 7:37
  • I measured the chainline it is about 47.5mm, the MTB standard. This bike is very tricky and I did not notice the spec when I brought it.
    – Bill Chan
    Dec 7 '21 at 9:33
  • @MaplePanda good idea, the spec said: Wider tire clearance Chainline +2.5 mm vs. conventional road FD
    – Bill Chan
    Dec 7 '21 at 9:36
  • @BillChan Is 47.5mm a current MTB standard chainline for 2x drivetrains? I was thinking it was wider. The GRX FD has a specified chainline of 47mm, so if your measurement was accurate it should actually work. FD-RX400 = Tiagra equiv. That said, I share everyone's confusion about your bike's specs. There's no indication in the official specs that the bike has an MTB BB shell or FD.
    – Weiwen Ng
    Dec 7 '21 at 15:44
  • @Bill Chan Is the actual shell 73mm wide? Even if it is (which would be truly weird) you could still put a 73x113 octalink BB in it and get to the right chainline with your cranks. Dec 7 '21 at 16:06

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