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New Di2 Road Bike, is the frame faulty?

by touring_bmore
Thu, Apr 02, 2020 19:19
13

*** SOLVED: I was missing the curved radius washer that goes between the bolt and the derailleur mount on the frame. Thank you for the help! ***

Dear community,

I just finished building up a Bowman Palace:R frameset with a new Ultegra R8000 Di2 groupset.
www.dropbox.com/s/1gyxm0b4cxbuzgt/01.jpg?dl=0
www.dropbox.com/s/dzg7f21bfquo40b/02.jpg?dl=0

But when I install the front mech, the lower end of the cage seems to be angled outwards and the upper end inwards. It's so bad that the chain rubs both at the top and the bottom.
www.dropbox.com/s/1fbnklj42wjd6l1/03.jpg?dl=0
Even the teeth of the chainring touch the cage and catch it no matter how high I move it.
www.dropbox.com/s/6fcqty339ulxo3m/04.jpg?dl=0

I can just not get the cage parallel to the chain. And the way I understand the manual, with the support bolt, I can angle the cage further outwards but not inwards. This is not the first time I am building up a bike, but the first time with Di2, so I carefully followed all the steps from the Shimano manual. Right now, the support bolt is not touching the frame so it's not responsible for it.
I am also pretty certain that the cage of my brand new derailleur is not bent out of shape:
www.dropbox.com/s/aqwrk94gki08742/05.jpg?dl=0

Normally, I would just rotate the derailleur clamp to align the cage but the Bowman Palace:R is only compatible with braze-on derailleurs. The only explanation I can come up with is that the front mech braze-on bracket on the frame is not aligned correctly.

Am I making a mistake or is there anything else I can try? Or do I have to send the frame back to Bowman Cycles and ask for a replacement?

Thank you for your help!

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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13 comments

Avatar
kil0ran | 4 years ago
2 likes

First up, lovely bike. I've got a Layhams that I absolutely love but I was seriously tempted to build up one of these when they were discounted.

A few things.

1. Have you installed the radius washer? It goes between the bolt head and the front of the braze on.

2. Back off the support bolt so it doesn't contact the frame on installation

3. Install the derailleur such that the outer plate of the cage is angled inwards (rear edge should be about 1mm inboard of the outside of the chainring

4. Then tighten the support bolt against the support bolt plate (make sure the plate is in the right place and the bolt is pushing against the bit that doesn't have the adhesive pad)

Step four will move the cage outboard and put the whole assembly under tension. This is the critical bit. You do the same thing with a mechanical group and it's essential to getting the cage aligned correctly prior to installing the cable.

Dealer manual is here - https://si.shimano.com/pdfs/dm/DM-R8050-04-ENG.pdf (page 39 onwards)

Avatar
touring_bmore replied to kil0ran | 4 years ago
1 like

Thank you so much!! The first thing on your list is what I was missing.

It was not included with the derailleur and the diagrams in the manual didn't explicitly show it had to be a curved washer so I just used a flat one. Getting a curved washer from my LBS solved the problem.

Avatar
Podc | 4 years ago
1 like

Hi. The only braze on FD I have fitted was 105, but it had a curved mounting surface. The corresponding curve on the FD went behind the mount, and the FD bolt had a curved washer under its head - this allowed the FD to be rotated and aligned correctly.

This image from Merlin Cycles hopefully shows it:

 

Avatar
touring_bmore replied to Podc | 4 years ago
0 likes

Thank you so much!! I did not use the curved washer because it was not included with the derailleur (it came with a separate band-on clamp). And in the manual, it only shows there has to be a washer but it's not explicitly clear that it has to be a curved washer. I picked up the curved washer from my LBS today and it solved the problem.

Avatar
hawkinspeter | 4 years ago
0 likes

No direct experience with fitting a front derailleur, but could if be that the chainring is too far out and thus increasing the chain angle?

Avatar
touring_bmore replied to hawkinspeter | 4 years ago
0 likes

Thank you for the comment but it's unlikely. It's a Hollowtech II bottom bracket so not possible to adjust the distance between frame and chainrings. Also, my problem is that the mech cage is angled outwards, not the distance in general. If the chainring was closer, it would push against the inside of the mech cage even more.

Avatar
touring_bmore | 4 years ago
0 likes

Picture 5:

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touring_bmore | 4 years ago
0 likes

Picture 4:

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touring_bmore | 4 years ago
0 likes

Picture 3:

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touring_bmore | 4 years ago
0 likes

Picture 2:

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touring_bmore | 4 years ago
0 likes

Picture 1:

Avatar
AfterPeak replied to touring_bmore | 4 years ago
1 like

I am not sure about electric groupset but the mech should come with a couple of small metal plates (one flat and one curved) that should be placed onto frame behind the mech. On 105 and ultegra there is a small screw that you screw in which presses against that plate and holds the angle of the mech.

Avatar
Podc replied to AfterPeak | 4 years ago
1 like

AfterPeak wrote:

I am not sure about electric groupset but the mech should come with a couple of small metal plates (one flat and one curved) that should be placed onto frame behind the mech. On 105 and ultegra there is a small screw that you screw in which presses against that plate and holds the angle of the mech.

Good point - if it has one and the little adjustment bolt is screwed too far in, it will be hitting the plate and holding the FD out at the angle shown. 

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