jlaw

I was reading another thread about these and someone mentioned a possible issue with index shifting this crank. Indexing would only be a problem for the FD not the RD, correct?

I'm looking to pair this crank with a 9 speed indexed RD using 9 speed chain.

Thanks!

SurferRosa

Correct. Rear derailleur indexing is dependent on the rear cluster, rear derailleur, shifters, and cable/housing.

ThermionicScott 

+1. If there is a problem with the crankset, it would be from the narrow 9-speed chain, and not the rear indexing. Even then, I'm optimistic that the narrow chain wouldn't be an issue for this crank.

TenGrainBread 

I'll also add to not bother with an indexing front derailleur. Friction is just better on the front.

thook

if i may piggyback....

friction > indexing on front: be that as it may, am i correct inferring that a vintage crank can be indexed, though?

The Golden Boy 

It depends.

It depends on if the rings have ramps and pins.

It depends on if the rings are the correct size for the FD in question- modern indexing FDs have sculpted cages that pretty much only pick up the chain when it's in the range it's designed to pick up.

It depends on if the rings are the right thickness.

There's probably other factors as well.

There's a reason front indexing came along much later than rear indexing.

The Golden Boy 

Do some searching around to find out if this is a cold forged crank or a melt forged/cast crank. You want cold forged.

If this is about replacing the N600 crank- you're going WAY down the ladder.

jlaw

Ok, don't want to do that. How about the Sugino Impel 500? Or what would you recommend?

The Golden Boy 

I'd keep the N600.

The only step up (IMO) is the Sugino AT.

natterberry 

Dave nailed it. I think the AT is the only real suitable replacement if that is truly what you want.

jlaw

I researched the difference between casting and forging - so now I know.

If I keep the N600 crank and want to change the outer and middle chain rings I need to get replacements with the proper 110/74 BCD, and rings made specifically for outer and middle - anything else?

And, 9 speed chain won't fall/get stuck between the chain rings on the N600 crank, correct?


Thanks.

dddd

Was some info perhaps edited/deleted here, I didn't see where the OP mentioned an N600 crankset and don't know what that is.

It's usually possible to get any double crank to index, for a couple of reasons.
The derailer travel can be tailored using the limit screws and cable tension, plus the newer double front derailer is typically designed to handle a variety of chainring size differential (unlike with modern triple front derailers).

The 9s chain may tend to fall between the chainrings, but a newer small ring should take care of that unless the crank spider tabs are of an unusual thickness. The small ring's teeth can be bent a half-millimeter over using an adjustable wrench (with the chainring removed of course). The chain falling centered over the small ring's teeth can be further fine-tuned using a file held against the rotating chainring, which subtly adjusts the lateral location of the tips of the small ring's teeth. The big ring isn't much of a decider in the chainring spacing, it all comes down to the small ring's tooth offset and tooth beveling.

The Golden Boy 

I'm using a 10 speed with my Sugino AT. I have a modern middle ring, but an old granny and big ring. I have had 2 instances of the chain falling between the middle and granny in the past 3 years or so. I do need to get a newer granny-

I have not done this on my N600.

The Golden Boy 

This came up in another thread from the OP-

The N600 is the 600 level triple chainset that came on the 85 Trek 620. It was 600 level, carried a 6206 model number, but was only marked "Shimano." Effectively, it was Shimano's high end road triple.

1985 Trek 620 by Dave The Golden Boy, on Flickr



Do you know if Shimano had another cold forged triple that's as graceful as the Sugino AT?

jlaw

I've been seeing some pretty nice vintage Deore LX cranks, 46/36/26 - 110/74 BCD, with "SG" rings on ebay for reasonable $. I may buy one of these and substitute one or more of the rings for what I have now - 50/45/28. This is a good incremental step and may mean that I'll keep the drivetrain a 6 or 7 speed.

The more I look at these vintage 5 arm cranks the more I like them compared to more modern stuff - especially once they are shined-up. I'm going to get a buffing wheel.

If I upgrade the wheels/drivetrain at some point I'll likely stay with 9 speed.

Good to know that you haven't had major problems using a narrow chain.

Thanks.