sillygolem

AKA "Reading Sheldon Brown makes me even more confused"

He mentions in his freewheel article that a "narrow" 6-speed freewheel will fit in a 70's 10-speed frame because of the chainstay spacing. However, he never says what "narrow" is.

Does this mean I can screw on, say, a Megarange freewheel onto my bike wheel without redishing it? With redishing but no cold setting the chainstay? Or is this narrow freewheel some obscure boutique part made by monks in the 1960's that only fits French threading?

nwbikeman

Suntour made a freewheel that they called an ultra 6 freewheel and was only a millimeter wider than a standard 5 speed freewheel for the original 120 spaced frames, yes early mid 70's. If you have about a 1/4" of clearance between the high gear cog and the frame you should be able to make is a regular 6 speed without any spacing changes. Same goes for 126 spacing with the same clearance could probably switch to 7 speed from 6 and still clear the frame. Or 126mm Shimano cassette hubs in both 7 and 8 speed.

Mike Mills

I think you will also need the Ultra 6 chain.

Road Fan

Not too sure about this.

Capecodder

You can run a 6 speed (Ultra Freewwheel) on a 5 speed setup MOST of the time with no problem, and use a 6 speed chain. The ultra freewheel is just a it more (narrow) than the regular 6 speed freewheel, and allows you to use it in a 120mm spaced rear (most of the time) not always...... You do not need to redish!

Road Fan

What is a 6-speed chain? Is it different from an 8-speed chain? What is an Ultra-6 chain?

Modern cassettes are pitched narrower than conventional 5-speed freewheels. What modern chain is designed for the correct pitch? I can see that conventional 5-speed chains might be too wide.

Capecodder

6-7-8 speed chains are the same.... you can use a 9 speed chain on a 7-8 speed setup and a 10 speed chain on a 9 speed setup. It won't shift as perfect, but will work OK.

Road Fan

Ok, this is more like it, thanks!

pastorbobnlnh 

The SRAM PC-850 chain works like a champ on an Suntour Ultra 6 or 7 Speed freewheel.

Silly, a Shimano Megarange 6 speed, however is not "Ultra" spaced, and in most cases will not work, because it is sized for 126mm dropout spacing.

But there are work-arounds to this challenge. Tell us more about the bike, post some pictures of the current freewheel and wheel, mounted in the dropouts, and measure your spacing. Tell us a little more about your objectives for the bike's future. What type of freewheel does it currently run.

These are all important pieces of information which help us give some great advice.

Best of luck!

Capecodder

I love my SRAM chains.... I've been using the PC-830 my LBS sells them for $12.00 with the Power Link!!!!

SJX426 

I put an ultra 6 on my 1972 Motobecane in 1976 or so. Worked just fine, I still have it (the Ultra 6) and the chain.

Mike Mills

They are different than a C&V "5 speed" chain - the pins do not protrude from the side plates. The pins on a five speed chain will interfere with the adjacent cogs due to the tighter spacing. If he's got a 70's 5 speed freewheel, he probably has a 5 speed chain, too.

As a true "stick in the mud", uh,... err, ... I mean C&Ver, I have never used one of those new -fangled 7, 8, 9 or 10 speed chains. Heck, those new-fangled Ultra 6 chains are a bit much, too.

sillygolem

I knew about the Ultra, but I wasn't sure if the newer freewheels were Ultra or regular spacing now that everything has shifted to tiny sprockets crammed together.

It's a Free Spirit with a 5-speed Shimano Freewheel. I'll measure it and take pics when I get home and put the axle back together. I had the freewheel removed at a bike shop because I didn't have the tool for it (seems to be Atom-sized and not normal Shimano-size) so I'm not going to put it back on.

I'm interested in the Megarange because the granny cog would let me run a single chainring on the front and still have a low ratio for some of the hills here. I could care less about having extra close ratios, I just want more range.

Capecodder

Then just go with something like this....

https://cgi.ebay.com/New-Old-Stock-Su...item5adb07bd28

sillygolem

I've got measurements and pictures.

The frame uses 120mm spacing for the rear axle.

With the original spacers there's about 33mm between the inside end of the freewheel threading and the dropout.

The original Shimano Free-Wheel (left) looks like it's 27mm thick, and just slightly narrower than a newer Shimano mountain bike freewheel (right) due to the threading. The original freewheel also has a noticeably recessed center: If there isn't enough space, 5th gear would be rubbing against the frame, but with the newer freewheel the center would be against the frame, allowing the freewheel to spin...er...freely.

Did anyone use Ultra spacing on anything other than the Suntour Ultra hubs?

old's'cool

I don't thing the recessed center makes any difference, since the freewheel locates on the hub of the wheel, not the axle (at least not directly). The axle, hub and spacers determine the width of the assembly, which needs to be compatible with the freewheel and the frame. When changing any of these elements dimensionally, something else may need to change to make it all compatible once again.
AFAIK, only Suntour made the "Ultra" narrow spaced freewheels. Changing from a 5 speed freewheel to an Ultra 6 can be fairly uneventful. Just make sure that there's a little bit of clearance between the chain on the 5 speed small cog and the frame before you decide to go to an Ultra 6. Use a "7-8" speed chain. Shifting (friction assumed here) may be a little bit trickier due to the smaller lever movements per gear. Also, this could be big issue depending on the gear range you're seeking, many have reported shifting difficulties with wide range Ultra freewheels. Mine happens to be a 13-19 and works pretty well; I have a little bit of difficulty getting the 4th cog instead of jumping over it sometimes.

cudak888 

Not exactly true. A 6-speed chain, back in the day, was the same as a 5-speed chain. Once Shimano came out with their narrow-chain 7-speed system - which has since been widely adopted by other manufacturers - these 7-speed chains became marketed as 6-speed compatible; for the Shimano 7-speed narrow chains are backward-compatible with most 6-speed systems.

However, some of these narrower chains do give trouble on older cranksets. Be careful when you select your system.

-Kurt