Bicycle Mechanics - Shimano 600 max teeth wrap

Hello all,
I have a shimano 600 rear derailler (RD6207) with a manufacturer's maximum teeth wrap of 28. i've been looking for a suntour ultra 6 speed, and have found a nice freewheel, but it is a 13-30. I use friction shifting. Would this freewheel be impossible to use with my current RD?

Thank you in advance.

Teeth wrap of 28 doesn't answer the question, but the 30 tooth is possibly "technically" too large anyway.

Tooth wrap has to do with the difference in teeth from your large/large to small/small combination... This is dependent on the ability of the RD to take up the chain slack in the various configurations. So assuming you have a 52/39 chainring combination, this would go from 52+30 = 82 to 39+13 = 52, Since 82 - 52 = 30, you would be just over the wrap capacity of the RD... if you are using a 52/42 you would be at 27, and would be fine for wrap capacity.

In looking at Sheldon Brown's site, it seems that he says that most Shimano rear derailleurs will handle rear cogs up to 30 teeth... http://www.sheldonbrown.com/harris/derailers-rear.html

He also stated that the values specified are pessimistic... If you don't cross chain a lot, you may be fine... I would give it a try if I were you.

Teeth wrap of 28 doesn't answer the question, but the 30 tooth is possibly "technically" too large anyway.

Tooth wrap has to do with the difference in teeth from your large/large to small/small combination... This is dependent on the ability of the RD to take up the chain slack in the various configurations. So assuming you have a 52/39 chainring combination, this would go from 52+30 = 82 to 39+13 = 52, Since 82 - 52 = 30, you would be just over the wrap capacity of the RD... if you are using a 52/42 you would be at 27, and would be fine for wrap capacity.

In looking at Sheldon Brown's site, it seems that he says that most Shimano rear derailleurs will handle rear cogs up to 30 teeth... http://www.sheldonbrown.com/harris/derailers-rear.html

He also stated that the values specified are pessimistic... If you don't cross chain a lot, you may be fine... I would give it a try if I were you.

My 1984 Trek 610 came stock with a 52/40 and a 13-28, shifted by a Shimano RD6207. The wrap was 12 + 15 = 27 teeth. The RD did shift it.

Hi.
.
There was a similar question here some time ago and if
memory serves, your Shimano 600EX (RD-6207) might handle
a 32 tooth cog on a six-speed freewheel (probably 7-speed
too) with a standard 52-42T front double.
.
I've got the same derailleurs on two mid-80s bikes and they
shift better with MF-6207 and MF-6208 freewheels than any
other derailleurs I have on other bikes. I like them better
than Shimano's SIS indexed version, which is pretty much
the same as Shimano's 105 and Light Action SIS RD versions.
.

I would agree - I think almost any derailleur will shift best with a Shimano-type cog tooth. I have not ahd the RD6207 work well with Regina or Maillard freewheels, not badly with Sachs-Maillard Aris cogsets.

I would agree - I think almost any derailleur will shift best with a Shimano-type cog tooth. I have not ahd the RD6207 work well with Regina or Maillard freewheels, not badly with Sachs-Maillard Aris cogsets.

FWIW, I've used Light Action, Exage 400/500. and 105 short cage RDs of the same vintage as your 600 with 13-30 rear clusters with no problems. I have one bike now with 53/40-13/30 gearing and an Exage 500 RD that shifts like a champ.
Top

I have a 1986 bike with RD6207 short cage - original freewheel was a six-speed 14-28, friction shifters. It worked fine with the original 52/40 crank, and also with the new Stronglight 53/39 rings on there now.

I set up a spare wheel with 13-30 cassette and that seems to work fine as well. I certainly wouldn't use the 30 on the big ring!

Also wrap-capacity is enhanced if you never cross-chain. That removes the extremes of wrap and the derailleur doesn't have to go through its full range of motion. I've used the 600EX RD with a 53/28 and 12-26t gears before without any problems.

Also wrap-capacity is enhanced if you never cross-chain. That removes the extremes of wrap and the derailleur doesn't have to go through its full range of motion. I've used the 600EX RD with a 53/28 and 12-26t gears before without any problems.

53/28??

Sorry typo, 53/38t; smallest that can fit on a 130mm BCD. I actually prefer the Hyperglide teeth-profile vs. the earlier Uniglide. The different teeth-profiles and ramps actually do shift without any slipping or grinding. Shimano actually had a 7-spd Hyperglide freewheel for a while. The top-cog was a slip-on one with an outside lockring; similar to the freehub cogs.

One comment to the OP. Sun Tour's Ultra 6 freewheels were made to allow six cogs to fit in the overall width of a 5-speed freewheel and so 6 speeds could be used with 120 mm dropout spacing. They required the same "narrow" chain as a regular 7-speed freewheel intended for 126 mm dropouts.

The knock against them was that they shifted rather poorly. I put a 13x28 Ultra-6 (with the required narrow chain) on a mid-80's Bridgestone as a low cost way of getting better gearing than the the 14x32 Sun Tour standard width six speed the bike came with. It worked but the shifting was noticably more reluctant under any load.