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Old 02-22-09, 01:35 PM   #1
fmullegun
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Drivetrain questions

I have an old mountain bike I am converting to road/fun use.

Need a new chain, so I have questions on any upgrades I need. I think I need new chain rings, but the rear looks OK.
Also the bearins feel terrible on the bottom bracket but I am hoping I can regrease and changes the ball bearings and make them much better.

Can you guys check out my pics and tell me what:

1. You would do to bring it up to great mechanical shape for cheap (which parts to replace)

2. Is my frame and rear hub still "modern" or am i severely limited (for instance can I just buy a new bottom bracket.

I already know about 7 speed not working with 9 speed stuff and frankly even if I only save a little I would just stick to 7 speed.


Pic 1

Pic 2

Pic 3
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Old 02-22-09, 01:56 PM   #2
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yes you need a new chain. you'll need to overhaul the bottom bracket , replace the bearings 22 1/4" balls and maybe the cups if they are in bad shape. or take the BB axle to your lbs and get a new sealed BB of the same length. you need to also cleans the rear gears. if the new chain slip on them then you need a new cassette (gears) too. while overhaul the BB also do the headset , hubs too, new grease & bearing of the right sizes. you may also need new brake pads & cables for the brakes & dérailleurs.
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Old 02-22-09, 02:08 PM   #3
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So you've got a square taper, cup & cone BB, nothing inherently wrong with that. Easiest approach - replace with cartridge square taper BB.
Biggest chain ring looks OK, middle kinda suspicious, small prolly OK too. As it usually is.
If you're gonna replace chain, do the cassette too. For everyone but the terminally lucky there's nothing but trouble ahead of doing one without the other.
From the pics you've posted that's about all there is to say.
Roading up MTBs has been a very popular theme here recently. Unless your MTB is really nice or you have a big pile of parts it can quickly turn pricey and awkward. But swapping to slicks and a road cassette(since you intend to replace the cassette anyhow) is often a reasonable effort. Trekking, or North Road bars is also within reach.
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Old 02-22-09, 02:11 PM   #4
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Originally Posted by fmullegun View Post
I have an old mountain bike I am converting to road/fun use.

Need a new chain, so I have questions on any upgrades I need. I think I need new chain rings, but the rear looks OK.
Also the bearins feel terrible on the bottom bracket but I am hoping I can regrease and changes the ball bearings and make them much better.

Can you guys check out my pics and tell me what:

1. You would do to bring it up to great mechanical shape for cheap (which parts to replace)

2. Is my frame and rear hub still "modern" or am i severely limited (for instance can I just buy a new bottom bracket.

I already know about 7 speed not working with 9 speed stuff and frankly even if I only save a little I would just stick to 7 speed.


Pic 1

Pic 2

Pic 3
If you can visually tell that the chainrings are worn to ****, i'll bet $10 that the cassette is gone as well. Meaning you'll need new chain + cassette + chainrings. Chain/cassettes usually go together. Chainrings usually last serveral iterations of chains before wearing out.
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Old 02-22-09, 02:56 PM   #5
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I think this is not just wear but abuse and neglect. The middle chainring has teeth broken off, and the chain is rusty and binds which is why I know I am 100% replacing it.

What do I need to know about my bike to buy the correct sized sealed BB? I read the after 1995 they used 68mm, this bike is 1992.

Also can I buy any 7 speed chain or are there different profiles or something? I would rather just try out my cassette and see if there is a problem before replacing it.

Last edited by fmullegun; 02-22-09 at 03:02 PM.
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Old 02-22-09, 03:03 PM   #6
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I think this is not just wear but abuse and neglect. The middle chainring has teeth broken off, and the chain is rusty and binds which is why I know I am 100% replacing it.

What do I need to know about my bike to buy the correct sized sealed BB? I read the after 1995 they used 68mm, this bike is 1992.

Also can I buy any 7 speed chain or are there different profiles or something? I would rather just try out my cassette and see if there is a problem before replacing it.
The teeth are not broken off. It was desinged that way to facilitate shifting. BB shell width is ridiculosly easy to determine. Go measure it. Once you take the cranks off the spindle length is also readily measured.

Any cheap 7 speed chain will do. Get one with a quicklink if you can. Forget the shimano chains.
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Old 02-22-09, 03:13 PM   #7
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Will any 7 speed chainring fit my bike also?
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Old 02-22-09, 03:26 PM   #8
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Just so I understand, the shell width is based on my frame size, but the spindle length is based on my cranks.

So if I bought an entire crank-chainring-sealed bottom bracket kit, I just need to make sure it is the correct 73mm or 68mm shell size?
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Old 02-22-09, 03:30 PM   #9
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Will any 7 speed chainring fit my bike also?
No, BCD has to match your crank. Or rings won't fit.
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Old 02-22-09, 03:31 PM   #10
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Just so I understand, the shell width is based on my frame size, but the spindle length is based on my cranks.

So if I bought an entire crank-chainring-sealed bottom bracket kit, I just need to make sure it is the correct 73mm or 68mm shell size?
They don't usually come as kits, but the crankset specs tell you exactly what type of bb it needs. Your shell width is what you measure of your frame.
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Old 02-22-09, 04:22 PM   #11
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Pricewise, you're probably better off buying a new crankset rather than new rings. For example, here's a decent-quality 42/32/22 triple that uses a standard square-taper BB, for $32: http://www.bikeparts.com/search_resu...p?ID=BPC123056
Having steel rings will be more durable, although somewhat heavier. A matching JIS square taper BB in 113mm or 118mm length (for 48.5mm vs 51mm chainline) will run you $15-20.

You should be able to get an SRAM 7-speed cassette with 12-tooth smallest gear for under $20; you'll probaly have to go with something like a Shimano HG-70 ($30 or so) to get an 11t smallest gear.

An SRAM powerlink chain like the PG-830 will run you $10-12.

For safety and performance, it's always a good idea to install new cables and housings for the shifters and brakes.
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Old 02-24-09, 10:32 AM   #12
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Can you guys tell me if these would fit my frame? I have a 68mm shell width.

eBay link 1

eBay link 2


I know the 9 speed chainrings will not work with my current shifters and cassette, but I am just talking about any problems other than that. ie will it screw into my frame.

Last edited by fmullegun; 02-24-09 at 11:10 AM.
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Old 02-24-09, 11:37 AM   #13
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Without seeing/taking some measurements, I can't say for eBay link 1, But the Hollowtech II one should. You'd need a Park Tool BBT-19 to install it. And a torque-wrench would be a good idea to check you're tightening it in snug and to specs. Here's the BBT-19:

http://www.parktool.com/products/det...25&item=BBT-19

Those Hollowtech II's are very nice. There is a cheaper tool than the BBT-19, the BBT-9, but I can't recommend it - there are accounts of it's failing. But here it is anyways:

http://www.treefortbikes.com/283_333...cket-Tool.html

You should clean your BB and clean the threads in particular before you install the Hollowtech II - if you decide to go this way.
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Old 02-24-09, 11:46 AM   #14
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According to the ebay ad, the first one is a 68mm BB, so it should fit fine, too. Either one should work with your current shifters/cassette, as the rear gears & shifter are pretty much independent of the front gears.
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Old 02-24-09, 11:58 AM   #15
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OK I didn't know if my frame was to old to accept this new stuff since it was the older square taper stuff.
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Old 02-24-09, 12:04 PM   #16
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OK I didn't know if my frame was to old to accept this new stuff since it was the older square taper stuff.
It'll do octalink/external fine. You really don't need a $150 external bb crankset. You can buy a steel ringed triple shimano crankset for $30-$50 without bb. Throw in $25 more for a LX/105 quality cart bb and you're set.
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Old 02-24-09, 12:09 PM   #17
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The square-taper/octalink/whatever are only differences in the spindle and determine what cranks will fit; it's the threading and size of the BB shell/hole in the frame that determines what type of BB will fit. 68mm (or sometimes 73mm) BB shell width and English threading have been pretty standard in the US for a loooong time, so you can just mount a BB that fits that and be good to go.

The external bearing type BBs such as your second choice above also require that the outer faces of the BB shell be parallel (or veeery close) or the BB will get stressed and often fail prematurely. If you go that route, I'd suggest having an LBS with the proper (expensive) tools and knowledge "face" the BB shell just to make sure it's nice and flat and parallel. This isn't normally so big an issue with the all-internal BBs such as your first choice above.

I agree with operator that something like your first choice will last a long time and work fine for you.
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Old 02-24-09, 12:16 PM   #18
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It'll do octalink/external fine. You really don't need a $150 external bb crankset. You can buy a steel ringed triple shimano crankset for $30-$50 without bb. Throw in $25 more for a LX/105 quality cart bb and you're set.
Can you link me that on a website for sale? Until I check out a picture and see the description I have a hard time knowing what you guys are talking about. I am a complete noob on building bikes, I've never changed any components.
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Old 02-24-09, 12:27 PM   #19
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fm - operator is talking about the same type of crankset as in your first choice, but is suggesting getting a higher-quality BB to go along with it. IMHO, I don't think you'll see any difference in performance by just going with the package in your first choice.

I would also *strongly* suggest buying (or checking out from your library) one or both of these two books:
http://www.amazon.com/Zinn-Art-Mount.../dp/193138259X
http://www.amazon.com/Bicycling-Comp...5500030&sr=8-1
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Old 02-24-09, 12:47 PM   #20
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This tool will pull both my cranks and the octalink cranks right?
http://www.rei.com/product/723014
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Old 02-24-09, 01:01 PM   #21
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Quote:
Originally Posted by fmullegun View Post
I have an old mountain bike I am converting to road/fun use.

Need a new chain, so I have questions on any upgrades I need. I think I need new chain rings, but the rear looks OK.
Also the bearins feel terrible on the bottom bracket but I am hoping I can regrease and changes the ball bearings and make them much better.

Can you guys check out my pics and tell me what:

1. You would do to bring it up to great mechanical shape for cheap (which parts to replace)

2. Is my frame and rear hub still "modern" or am i severely limited (for instance can I just buy a new bottom bracket.

I already know about 7 speed not working with 9 speed stuff and frankly even if I only save a little I would just stick to 7 speed.
Your drivetrain is worn enough that changing the rings, chain and cogs would likely save you a lot of grief in the long run. A new BB cartridge ought to work fine.
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Old 02-24-09, 01:04 PM   #22
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Your drivetrain is worn enough that changing the rings, chain and cogs would likely save you a lot of grief in the long run. A new BB cartridge ought to work fine.
yeah I am slowly realizing it might be a good idea to just replace it all in one go.
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