Dura-Ace 7400 and Chain Line
05-15-20, 04:59 PM
#26
Junior Member
Thread Starter
I bet the chain width is the problem. I "upgraded" from 6 speeds to 7 speeds when I moved to DA from 105. Could that be it?
05-15-20, 05:10 PM
#27
Senior Member
Join Date: Jun 2006
Posts: 20,305
Mentioned: 130 Post(s)
Tagged: 0 Thread(s)
Quoted: 3464 Post(s)
Liked 2,827 Times
in
1,995 Posts
my vote is the front derailleur cage, a 105 series is thicker than the earlier Dura-Ace from the appearance shown in the images.
Likes For repechage:
05-16-20, 04:07 AM
#28
Full Member
Join Date: Apr 2007
Posts: 253
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
Likes: 0
Liked 22 Times
in
12 Posts
I think your crank arm is bent.
I have two 7402 crank sets and a 6400 crank set. On my 6400 crank, there is almost a 3 mm gap between the crank arm and the alignment pin on the big chain ring. On one 7402 crank there is a gap of about 2.5 mm between the crank arm and the alignment pin. On the other 7402 crank set, there is no gap at all - the crank arm touches the pin on the chain ring. Out of all the dozens of crank sets I have had, I never had one without a gap between the arm and the pin until this one. I got it used so I don't know its history but I think it's bent because there are significant scrapes on the inside of the crank arm where it clearly was hitting the derailleur on someone else's bike. I got that crank set as part of a package deal when I bought a full 7400 group but I haven't used it because it's too short for me.
Check to see if your crank arm has a gap between the arm and the alignment pin on the chain ring. If there is no gap, then I think your crank arm is bent inward like mine. If there is a gap then the 1050 derailleur must not be compatible.
I have two 7402 crank sets and a 6400 crank set. On my 6400 crank, there is almost a 3 mm gap between the crank arm and the alignment pin on the big chain ring. On one 7402 crank there is a gap of about 2.5 mm between the crank arm and the alignment pin. On the other 7402 crank set, there is no gap at all - the crank arm touches the pin on the chain ring. Out of all the dozens of crank sets I have had, I never had one without a gap between the arm and the pin until this one. I got it used so I don't know its history but I think it's bent because there are significant scrapes on the inside of the crank arm where it clearly was hitting the derailleur on someone else's bike. I got that crank set as part of a package deal when I bought a full 7400 group but I haven't used it because it's too short for me.
Check to see if your crank arm has a gap between the arm and the alignment pin on the chain ring. If there is no gap, then I think your crank arm is bent inward like mine. If there is a gap then the 1050 derailleur must not be compatible.
Last edited by Fivethumbs; 05-16-20 at 02:46 PM.
05-16-20, 08:33 AM
#29
aka: Dr. Cannondale
Join Date: Jul 2009
Posts: 7,726
Mentioned: 234 Post(s)
Tagged: 0 Thread(s)
Quoted: 2152 Post(s)
Liked 3,401 Times
in
1,203 Posts
Outer ring is a SG B53 Chainring, and there is 7.27mm of clearance between the crank arm and the face of the big ring. I'm pretty positive the crank arm is straight.
The pictures showing the lack of clearance between the chain/FD are with the chain on the smallest rear sprocket. Based on what you mention, rccardr, I'm wondering if the front derailleur might be the problem after all.
Ok--just realized what might be the problem. I'm running a 6-speed chain. I just measured the links and they are 7.76mm. I dug out my backup Sedisport chain and it's measuring between 7.02-7.1mm. This bike was originally 6 speed 105. Should I swap chains?
The pictures showing the lack of clearance between the chain/FD are with the chain on the smallest rear sprocket. Based on what you mention, rccardr, I'm wondering if the front derailleur might be the problem after all.
Ok--just realized what might be the problem. I'm running a 6-speed chain. I just measured the links and they are 7.76mm. I dug out my backup Sedisport chain and it's measuring between 7.02-7.1mm. This bike was originally 6 speed 105. Should I swap chains?
If you want, I can send you a functionally fine but cosmetically challenged braze on DA7700 FD (you’ll need a 28.6mm clamp) and a used narrow chain, yours for the cost of postage.
If so, e-mail me at rccardr@cox.net and we’ll get it done
__________________
Hard at work in the Secret Underground Laboratory...
Hard at work in the Secret Underground Laboratory...
05-16-20, 08:00 PM
#30
Junior Member
Thread Starter
Thanks so much for the kind offer! I'll contact you via PM.
