Bicycle Mechanics - Overhauling 6-spd drivetrain but I can't find parts!

My stepfather has an old 6-speed Mongoose hybrid that fits him really well so he wants to keep it. Unfortunately, the shifting is pretty sloppy and I can't seem to get it tuned right.:crash: The fact that it still has the original chain and cassette could have something to do with it. Before I tell him that it's not worth it to dump any money into this rig, I need to know where I can find 6-speed parts, specifically a chain and maybe a crankset. I found a cassette on Nashbar for a decent price. If no other 6-speed parts exist, would I be able to use a 7-speed chain and crankset if absolutely had to? Or what about this? Would a 7 speed rear fit on the same freehub (I know, I'd need new derailleurs, shifter, and definitely a new crankset)? I just want to see how much this will cost before I talk him out of it. Thanks, guys.

Well to fit a 7 speed cassette on a six speed freehub you would have to respace the drive side axle to accomadate the added length of a 7th cog. This is no big deal, sometimes you can swap spacers provided on the wheel. You may have to spread the frame for most frames made with a 6 speed rear were spaced 126mm and 7 speed is 130mm. As far as the drivetrain goes the rear der may make 7 speed changes if you adjust the H limit stop correctly. New shifters would be absolutely neccesary unless he has thumbies that can go to friction.
As far as the existing condition of the shifting, replace the cables and housing, clean and lube the chain and drivetrain components before changing parts to see if this works. If not most LBS can still acquire six speed stuff. However if you are going to be like alot of people and sho ponline then go here: http://www.bikeusa.com/components/
They have alot of six speed stuff just not 6 speed cassettes. They are a Lawton Ok LBS and can help you.

You should be able to find parts for a 6 speed setup.
SRAM chains have a large selection, you can check
availability here SRAM (http://www.sram.com/product/index.asp) . They list PC1 and PC10 as fitting 5-7 speed systems.
Cassettes may be a bit more difficult, but check on e-bay
as alot of older vintage components frequently list there.

Marty

Lotek a PC1 is a 1/8 inch chain designed for a single speed. Wouldn't a PC-68 work fine, it is a 8sp chain but 8sp is the same width as 6 speed chains.

Kev,

I got the info from the SRAM site, they list PC-1 as
5-7 speed.
When you click on the PC-1 is states SRAM single or
shimano.
Pretty unclear if you ask me.

thanks for the correction.
Marty

THat is strange SRAM should fix their web site, I believe you can use any 6-7-8 speed chain. The width changed when they went to 9-10sp.

I have been using the 68 on my six speed and seven speed and have not had any problems.

1) There were two overlock axle widths for 6-speed freewheels: 126mm for standard, and 120mm for "ultra." Particularly if you lose the spoke protector, you can almost always replace a standard 6-speed freewheel with a standard (which is always "ultra" spaced) 7-speed, although the latter officially requires a 128mm overlock.
2) If you use friction shifting, you can freely swap between standard 6 and ultra 7 speed freewheels.
3) There are basically only 4 types of 1/2-inch pitch bicycle chains: 1/8" for bikes with single cogs (track bikes, 3-speeds, Nexus 7-speeds, etc.); standard 3/32" for bikes with up to 8 cogs on the freehub or freewheel (I like the SRAM PC-58); slightly narrower chains specifically for 9-speed cogsets;and even narrower chains for 10-speed cogsets.

Are the rear cogs on a screw-on freewheel or a splined freehub? A freehub has a small splined lockring with "lock" and "unlock" arrows. The freewheel just has some splines for the removal tool.
You can get replacement freewheels. I started with a 5, but over time changed to a 6 then 7 with no modifications needed.
If its a freehub (unlikely in a cheap, older bike), Shimano have made a number of alterations to the splines over the years, so be careful to get the right version.
You can use 8speed components (chain, cranks, chainrings) with 5-8 cogs at the rear.

The bike is a Mongoose Crossway 250 purchased in '95 when I was about to go to college. It has 700c wheels, canti brakes and an 18 speed Shimano Altus drivetrain with grip shifters. I knew nothing about bikes back then and never really rode it until I discovered that I liked trail riding a few years later (you wouldn't believe some of the places I tried to take this thing!) When I got a real mountain bike I had no further use for it, until my stepfather realized how comfortable it is for him. It got him back into cycling after a 20 year layoff so I would like to keep it rideable as cheaply as possible. Everything on the bike is original, so the drivetrain is wearing out. That's why I want to replace the chain and cassette at the same time. I know new cables will probably help, but I don't know if it would be worth it. I will take a closer look but the cassette looks like it's a modern freewheel/lockring design. Since the shifters are indexed I need to stay with 6 speed. Since I can't find too many 6 speed parts around I wanted to know if I could use a 7 or 8 speed chain with it. Thanks for all your help. I'll look up some prices on the sites you suggested and run them by the old man and what he wants to do.

MichaelW said he upgraded 5 to 6 to 7 freewheel without modification.
Last April when replacing a 5 speed freewheel that had the 14T sprocket stripped, I thought it might be an opportune time to upgrade to an 11/34 freewheel (steel frame so respacing dropouts would be no problem if longer axle and spacer were obtained). I was told I needed to change the derailleur and shifters to avail myself of the 7 sprockets.
Did you have 5 speed indexed shifters or something else? If so, sounds like the LBS was off the mark.
Has anybody else tried this and had problems?
Is the 7 speed upgrade more likely a problem with the shifters or the derailleur?

Loose Screws (http://www.loosescrews.com) has customizable 6 speed freewheels and other odd parts for older drivetrains.