1991 M500

[TheLizard]

I'm starting a restoration on a 1991 model M500. Needs a lot of work!

This is my first vintage bike restore (although I've refurbished some newer bikes), so I thought I'd pose some questions I have to the experts!

The bike has the original Suntour x-1 accushift group set (sans the rear derailleur). I think I can get everything restored to working condition, to include the brakes and shifters. The bottom bracket is shot, but I think a new part the right size and spindle length should work.

So... without replacing the entire drive train (since most of it can be made to work), is there another part that would as a drop-in replacement for the X1 derailleur? I'm not sure what would be compatible. It looks like the original accushift freewheel is on there too. I've found a couple of used replacements but they're banged up or non-functional.

I have the same question about the chain and the cables. I've heard that standard modern cables don't work. Apparently this set also came with an "Suntour accushift chain", which I have no hope of finding, so I'm wondering what to look for in a replacement chain.

THANKS!

 

[Brian]

Hello,

Suntour and Shimano have different pull ratio's. It depends if you are going period correct. Or exact M500 restoration. If the bike got a upgrade down the road you could go with anything.

For Suntour, the parts are harder to find than shimano. But any Suntour der would work of that time range.

A chain is a chain. I personally go with new chains. I like SRAM chains, but it looks like they might have changed things. You just need the correct speed/width.

Usually 8/7/6spd chains are the same.

https://www.parktool.com/blog/repair-help/chain-compatibility

 

[black lightning 1987]

The 7 speed X-1 rear derailleur was used at least from 1990-1992, same model number. There are a number of derailleurs that would be functional replacements, including: XCT, XCM, XCE, XC LTD, XCD, XC Comp, and XC Pro (lower groups to higher). I suspect that there are several from the 6 speed era that would work as well. Not sure if I have tried a rear derailleur from the 6 speed era with 7 speed, will have to look at a couple of bikes.

The bottom bracket should be easy. Just buy a cartridge Shimano with the same spindle length as your old one. I think that 116 mm was pretty common for mid range SunTour triple cranks. Shimano 117 should be close enough. Be aware of Shimano E-type BBs. They may work fine but will require a spacer on the drive side equal to the thickness of an E-type front derailleur (about 2 mm I think).

It's always nice to use a SunTour freewheel with their groups but the freewheels are getting pricey, both new and used. According to Sheldon Brown, Shimano and SunTour 7 speed freewheel spacing is the same.

https://www.sheldonbrown.com/cribsheet-spacing.html

I may have a modern (China made) Shimano 7 speed freewheel on a SunTour bike but would have to check to be sure. At any rate they are cheap and work well, though not much to look at.

For cables just use Shimano stainless, Jagwire, BBB, Clarks, etc. Housing the same brands, 5 mm OD. Chain is the easiest of all. I probably have at least 10 bikes with SunTour drivetrain but haven't owned a SunTour chain in at least 25 years. I've had great luck using Shimano and FSA 9 speed chains on 6/7/8 speed bikes, and it's hard to go wrong with KMC chains. No real issues with SRAM other than that their connecting link can be difficult to release compared to the KMC. I haven't looked lately, but a few months ago you could buy the FSA 9 speed chains dirt cheap on ebay in several different quantities. I quit watching them when I had 40 or so on hand......

Let me know if you don't find a rear derailleur to your liking. I might have something on the shelf.