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Trek 820 - Craigslist Buy
#1
So I just bought this 820 off craigslist. It was in pretty bad shape and still is aside from a new, complete, rear rim.

So I noticed the crank is loose and could probably use some bearings. As for the drivetrain itself, it seems ok, but I don't know. Chain folds on itself when coasting or peddling backwards. Also crank rubs on front derailer.
Teeth are a bit chewed up on the cassette. The head squeeks pretty bad and looks like this thing had probably sat in one or three rains.


Some things I could use some help with from members.
1. What would be some good Bearings for crank?
2. Recommended pedals for road and gravel travel(non lock)
3. What would be some good bearings for the head?
4. Drive train upgrades? Can I piece or must it be complete?

Thanks I appreciate all the help.

Jerry
[color=#0000CD][align=center]Trek 820[/align][/color]
[align=center]Love when squirrels dart across the path...[/align]
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#2
A few things:
- The chain pulling forward when you coast indicates that the freewheel (I think you have a freewheel and not a cassette, but could be wrong) is gummed up. Look at trying to flush some lube into the freewheel.
- Your front derailleur is set too high. The rubbing on the crank is probably an adjustment issue. You should go through a step by step adj. of the front including proper alignment of the derailleur itself on the frame.
- Your chain is pretty stretched and you may want to replace it. If you do have a cassette, you would probably have to replace that at the same time. Not as critical on a freewheel, but if it's gummed up anyway, might not be a bad idea.
- I wouldn't bother "upgrading" your drivetrain in general. Replace worn parts with as good or better stuff and save your money for upgrading parts that will have a bigger impact on performance (tires, brakes, pedals,...)
- For bottom bracket bearings, the mid-range shimano cartridge bearings are decent.
- For the headset, it's quite likely that these bearings just need to be cleaned and regreased. I'd take a look before I bought replacements.

good luck
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#3
pedals: I like: http://www.amazon.com/dp/B00165OKYA/

you need the 9/16" version.

I have big feet, and these provide could platform coverage, and have proven durable for me.
Nigel
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#4
Thanks Dave and thanks nfmisso. Took her for the first ride (13 miles) since I bought it and new rim installed. Still needs some work; has some pinging in the crank, so I was looking at the Alivio crank. pretty cheap, as it seems. Question, how do I determine 175mm or 170mm? And do I need to buy the rear components to match as well?
I have been looking at some others posts here on this forum(pedals, thanks nfmisso) and have a few things others have recommended; brake pads, tires seats etc.

edit:
How do I know which bearings to get for the crank/head? Is there a size I need for this model?

edit#2:
Which size chain if I am remaining with the stock set up?
[color=#0000CD][align=center]Trek 820[/align][/color]
[align=center]Love when squirrels dart across the path...[/align]
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#5
Hi xtatic, and welcome to BT! I know Dave and Nigel won't mind if I try to help here.
Let's start with your BB (bottom bracket) and the noises. If you have checked that the crankarms are tight to the BB spindle via the bolts/nuts under the plastic caps, try to rock the crankarms and feel for any play. Also, does it feel smooth when you rotate the crankarms with the chain off? You want to isolate problems as best you can. Hence dropping the chain off of the rings and let it rest on the BB shell.
You can't replace bearings in your BB - it uses a sealed cartridge bearing that you simply remove, recycle and replace. You'll need to first know the width of your BB shell. As the 820 is a steel frame, 68 mm width is my bet. Then, you'll need to extract the arms and measure the overall length of the axle in mm. You should wind up with a number like 68 / 118.

The 820 uses a Square Tapered spindle and has English threading on the body of the cartridge. Most likely a Shimano model UN26 which should be able to be had for ~ $14. You can bump up in quality to a UN54 for ~ $24.

Be warned, though - if you change from one crankset (not Alivio) to an Alivio, there is a real possibility that you will need a diff length spindle. Base your spindle length on what the Mfr recommends for that crankset.

170 or 175 mm refers to the length of the crankarms. Longer for taller people. That's up to you and how you feel with your current length. It's measured C/L to C/L of axle spindle to pedal spindle. I am 5'6" and prefer 175's on my MTBs. That's just me.

Your replacement chain will need to be purchased for use with the number of sprockets at the rear. Example - 8 spd, 7 spd, etc. 7 and 8 usually work okay with the use of a SRAM PC-830 chain. Probably $15.

I have been a mech at a Trek shop for over 20 years and I apologize that I can't give you specific details. There is just WAY too much for me to remember! That plus spec changes within model years.

Let's get these issues resolved before we move on to the Headset. Is that the part that you were referring to in Edit #1 of your last post?

Edit - Dave is correct on the FW. New 820's still use a freewheel rather than a cassette.
Wheelies don't pop themselves. (from a QBP fortune cookie)
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#6
(11-06-2013, 12:50 AM)RobAR Wrote:  Hi xtatic, and welcome to BT! I know Dave and Nigel won't mind if I try to help here.
Let's start with your BB (bottom bracket) and the noises. If you have checked that the crankarms are tight to the BB spindle via the bolts/nuts under the plastic caps, try to rock the crankarms and feel for any play. Also, does it feel smooth when you rotate the crankarms with the chain off? You want to isolate problems as best you can. Hence dropping the chain off of the rings and let it rest on the BB shell.
You can't replace bearings in your BB - it uses a sealed cartridge bearing that you simply remove, recycle and replace. You'll need to first know the width of your BB shell. As the 820 is a steel frame, 68 mm width is my bet. Then, you'll need to extract the arms and measure the overall length of the axle in mm. You should wind up with a number like 68 / 118.

The 820 uses a Square Tapered spindle and has English threading on the body of the cartridge. Most likely a Shimano model UN26 which should be able to be had for ~ $14. You can bump up in quality to a UN54 for ~ $24.

Be warned, though - if you change from one crankset (not Alivio) to an Alivio, there is a real possibility that you will need a diff length spindle. Base your spindle length on what the Mfr recommends for that crankset.

170 or 175 mm refers to the length of the crankarms. Longer for taller people. That's up to you and how you feel with your current length. It's measured C/L to C/L of axle spindle to pedal spindle. I am 5'6" and prefer 175's on my MTBs. That's just me.

Your replacement chain will need to be purchased for use with the number of sprockets at the rear. Example - 8 spd, 7 spd, etc. 7 and 8 usually work okay with the use of a SRAM PC-830 chain. Probably $15.

I have been a mech at a Trek shop for over 20 years and I apologize that I can't give you specific details. There is just WAY too much for me to remember! That plus spec changes within model years.

Let's get these issues resolved before we move on to the Headset. Is that the part that you were referring to in Edit #1 of your last post?

Edit - Dave is correct on the FW. New 820's still use a freewheel rather than a cassette.

This is great info. Took it for another ride and after 11 miles of road, the bb has play. So, ordering the un54 and a new chain. Keeping all the old stock drivetrain. Just gonna clean it up. A lot of the cablrs need replaced. Rusty and need help. Thanks for the help. Im sure if i have more questions, ill be back. :-)
[color=#0000CD][align=center]Trek 820[/align][/color]
[align=center]Love when squirrels dart across the path...[/align]
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#7
So I finallybhad time to buy some tools..enough to get my bottom bracket out. Here it is..no bearings inside the plastic part. Measures at 4 7/8" from end to end. So in mm, what should I be measuring. I don't have a mm tape measure.
[color=#0000CD][align=center]Trek 820[/align][/color]
[align=center]Love when squirrels dart across the path...[/align]
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#8
On my Treks the bottom bracket size is stamped on the frame. Flip the bike over & look. Here's a pic, showing 122.5 UA53. I like Tange BBs rather than shimano.
[Image: BBMarkings2.jpg]
4 7/8" would be a 123.8mm

Here is a good rule to follow. If the rear cogs look worn, you replace the chain AND the rear gears at the same time. If the chain is stretched too much the same applies, you replace both.
Your pedals look fine, but if you need new ones I recommend Wellgo LU-313 which are marketed under a bunch of names. You need a 9/16" pedal. Even Walmart has a version for $20 a set.
Is there play in the headset?
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#9
(03-05-2014, 02:55 AM)1FJEF Wrote:  On my Treks the bottom bracket size is stamped on the frame. Flip the bike over & look. Here's a pic, showing 122.5 UA53. I like Tange BBs rather than shimano.
[Image: BBMarkings2.jpg]
4 7/8" would be a 123.8mm

Here is a good rule to follow. If the rear cogs look worn, you replace the chain AND the rear gears at the same time. If the chain is stretched too much the same applies, you replace both.
Your pedals look fine, but if you need new ones I recommend Wellgo LU-313 which are marketed under a bunch of names. You need a 9/16" pedal. Even Walmart has a version for $20 a set.
Is there play in the headset?
OK. So the bottom of my frame doesn't say what the number is? I don't think anyway. Also how do I measure the smaller number of the bracket. I don't know if I need a 68/123.8 or a 73?
I have teeth missing on front cogs. Rear cogs are severely worn and chain is severely loose.
Headset doesn't have play but from what I'm seeing so far...this bike has never been serviced...ever.
[color=#0000CD][align=center]Trek 820[/align][/color]
[align=center]Love when squirrels dart across the path...[/align]
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#10
The parts on a bike are interrelated, and when you just look at them as individual parts you lose the opportunity to really understand what needs to be done. Having the assistance of someone on hand can give you the info that is often missed when having to type instructions. Not everybody has a local resource - but you do. So get off the Internet and get over to the Des Moines Bicycle Collective! In-person help trumps getting bits and pieces online. http://dsmbikecollective.org/
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#11
Thank you! I'll check them out. :-)
[color=#0000CD][align=center]Trek 820[/align][/color]
[align=center]Love when squirrels dart across the path...[/align]
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#12
You know you need a new chain (a KMC will run you under $20) and new rear gears (about the same $$). You don't choose a BB until you know which crank set you're getting.
That bike collective should help. Great idea.
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#13
" I don't know if I need a 68/123.8 or a 73"

The 68/73 measurement is the width of the BB shell on the frame in mm. So measure the width of the frame tube itself (not including any of the BB cups or other parts).

The 123.8 refers to the length of the axle in your BB. But that is determined by your crank set. So if you get a new crank, the 68/73 won't change, but the axle length may. Note finally that you don't have to be exact on the axle length. +/- a couple mm won't hurt anything usually.
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