# Old school tech question: Has anyone used a 7410 DA crank w/a 7400 bottom bracket?



## texbike (Oct 21, 2004)

I'm helping a friend with a build using some old parts that are laying around. We have a Dura Ace 7410 crankset (the old 8 speed kind) and a 7400 BB. There was a bit of difference in the spindle length between the two (the 7400 being about 5 mm longer) and I'm concerned about the impact on the chainline with a 130 spaced frame. Fortunately both BBs are the required square taper.

Has anyone used a 7410 crank with a 7400 BB? What was the result? Any issues?

Thanks!

Texbike


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## paul l (Aug 3, 2009)

TB, did you ever pick up information on this?

One of my bikes has an old 7410 crankset and when riding it during the summer I got a click on the pedal stroke. Tried to trace it over a few rides, could not decide either way if it was the BB but decided to remove, inspect, re-fit and replace if necessary.

I was proud of myself for buying the tools, reading up and extracting the cranks and the BB. Part of that therapeutic don't be lazy, learn to look after bikes thing that I put off for years. The Dura Ace 103mm BB looks in superb condition (probably 3 years old) and spins smoothly but perhaps they all do when in your hands and not under pedal force.

The left hand cup was suffering at the outer edge though. This may not affect performance and is the opposite end to that which threads into the BB shell. Nevertheless, I tracked down a spares supplier and have a couple of left hand cups coming together with a new UN54 BB (LBS prices in my area for the BB alone being the same as the BB, cups and postage put together).

No-one seems to have any NOS 103mm BBs left for this crank any more but a mechanic assured me that 107mm works just fine and the 4mm sticking out of the left crank is not an issue tehcnically nor should it affect pedalling. We shall see.

If this maintenance does not work then the whole crank will give way to a new external-BB based chainset such as SRAM Rival, FSA MegaExo or a Shimano offering within that £90 to £100 price zone. Then it's a different ball game of which supports 9 and 10 speed so I can replace rear mech and brifters (both 90s era DA7700) at my leisure, not be forced into it. 9/10 speed compatibility is the reason the FSA is on my list.


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## paul l (Aug 3, 2009)

Quick update to say that the 107mm axle length UN54 in place of the old 103mm Dura Ace BB immediately knocked out the ability to change up from the small (39) to big (52) chainring. The 4mm difference meant insufficient travel despite using downtube friction shifter for front derailleur.

However, a quick adjustment of L and H screws sorted it simply and I have noticed no chainline issues on subsequent rides.


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