Dura Ace 7400 Chain Alignment

V

v11boy

Dirt Disciple
Hello

Does anyone have any advice on this please - I am running dura ace 7400 on my Peugeot perthus which has a 115mm square taper bottom bracket, when in the large front ring and smallest rear sprocket the chain just hits the crank arm and also the small amount of thread coming from the pedal shaft.

It's running 8 speed with 600 hubs.

I was thinking of either

- machining the pedal spindle back and living with the slight clipping of the crank arm when in top gear

- fitting a 118mm BB instead, but that may well still have the same problem given the arm would be just 1.5mm further out from where it is now.

Has anyone else had this issue using the same setup by any chance before I start messing?!

Thanks for reading.

Dan
 
First thought... lovely bike!

I don't have the same setup, so unfortunately I can't talk from direct experience.

However, you're already running a spindle longer than the spec for 7400 so you should, theoretically, be well clear. Something looks to be amiss, so I'd get someone to check it over in person.

That said, cheap fix would be spacers on fixed (right) cup and right pedal. 1mm on each should fix it without causing much of an issue.

Edited to add:

I've looked at the pics again and am now wondering what type of botom bracket it is? The cranks look pretty close to bottoming out on the taper.
 
Re:

Hello

That sounds like a much simpler approach thank you!

I've added a few more images to the album of the shimano markings on the face of the drive side cup.

It's even better to ride more than to look at!

Thanks
Dan
 
Ignore my suggestion of the spacer under the fixed cup... That was after a glass of wine last night and is no use whatsoever in this situation.


I resorted to Google before bed as this I was bugging me and it seems like 7400 cranks may have had a slightly different taper from standard JIS, but I'd still get someone to check this issue in person.
 
Run some string from the dropout to the headtube and back to the other dropout - then measure the gap between the the seat tube the string. That should give you an idea if something is amiss.
 
Maybe its just the photo's but check the crank arm isn't bent slightly

^^^ just about to say the same :LOL:
 
was the frame a 126mm one that was later cold set to 130? that would cause the chain to be further out from the bike's centre line when in the bottom sprocket

i was under the impression (possibly wrongly) that all perthus were 126mm. I'm also led to believe that you shouldnt cold set 753.
 
Re:

Thanks so much for the responses

- will check crank arm isn't bent
- can do a string line to double check the frame is straight too
- OLD is standard 126mm, not cold set. Wasn't an option given the 753 tubing as you said.

Again thanks, can't believe there's this many people who are as enthusiastic as me about old frames

Cheers
 
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