Tonga

First let me say I have read some posts on here and you people are great, you remind me of boat repair sight I used to moderate.

I purchased my grandsons a used trek 820 mountain bike from one of my guys at work. I cannot accurately tell you the age because it was never used and garage kept.

My grandsons is a large 13year old in excellent physical condition so he put some stress on the bike.

Anyway the hanthebar slipped and rotated in the stem at some point. Now the 13 year old boy continued to use the bike and apparently it happened again, then again. I am sure you all know if this was corrected the first time things would be fine. Instead my grandson tells me the bike is broken. I find the clamping bolts now cannot be made tight enough to prevent the slipping.

Problem if this thing was an evinrude , mercury, Yamah I would know exactly what to buy but I am not a bike mechanic.

I do not know how to find parts or how to determine if they are the correct parts?

I also do not know anything about aftermaket parts for a trek bike? I dont know what brand makes quality parts? what brands are poor quality?

I think what I wouldike is to purchase dtock OEM parts, the parts I think I need are a handlebar and a stem, (not positive stem is the correct name but it attaches the handlebar to the bike..

If OEM parts are not available or they are inferior to reasonably priced after market parts then I gues that is what I would do.

So I need parts HELP! os what I am saying.

M Rose

First off, Trek bikes are very easy to tell the year. The serial number is stamped on the bottom of the “Bottom
Bracket” (BB), HERE is a breakdown of TREK serial numbers (very similar to the way you break down a Johnson Serial number). Once you determine the year just go to https://archive.trekbikes.com/us/en/ and select the correct 820 Model as there were several although they all used the same handlebar and stem.

the Stem is measures 1 1/8” head tube (top portion of the fork that the steering bearing ride in) 25.4mm Handle Bar Clamping diameter, 25 degree angle. All of these measurements are standard moderne day Mountain Bike (MTB) dimensions minus the stem angle. I notice that the stem length isn’t given either. Stem angle and stem length are determined by specific rider fit (Search MTB Rider Fit handlebar and stem selection).

Since the Stem Clamp is unable to clamp properly you need to determine if the fork is also messed up. If the fork is stripped as well as the clamp, it will never tighten correctly. I would go to your local bike shop (LBS) and have them look the bike over and give you the best advice for repair. They may have used parts laying around the shop (most do) or at least give you a place to start looking for correct parts on Craig’s List, eBay, and/or Facebook Market Place as well as directly from Trek.

M Rose

Ohh forgot to mention OEM Bontrager parts are still available for the 820’s.

M Rose

I did a little more digging on your grandson’s 820. There weren’t any noticeable changes between the introduction of the 820 and now. All of the factory parts are listed by part number with a link to the parts on Treks page. Scroll down to the bottom of the page and select Specks. From there you can see the the different bars and stems used for specific sized frames to get you a starting point to decide to use stock parts or look for aftermarket parts.

https://www.trekbikes.com/us/en_US/b...olorCode=black

dedhed

You do know the Trek 820 has been around since the 1980's and has changed drastically since then? It was a lugged steel rigid Mt. bike.
Without knowing general age his stem may be a quill stem for a 1" threaded fork or a 1.125" threadless fork

First we need to know if it's a quill stem or threadless. Either way if handlebars are slipping in the stem a quick beer can shim often helps

​​​​​​https://www.vintage-trek.com/images/trek/Trek88_1.pdf

dedhed

First determine what type of stem you have quill or threadless.
https://www.parktool.com/en-us/blog/...&area%5B%5D=54

wheelreason

If memory serves right the original trek 820s had 1" threaded forks, then went to 1 1/8" threaded, and then to 1 1/8" threadless. sold a gazillion of them back in the 80s and 90s.
OP, A picture will put this baby to bed, while trek did make or source branded stems, any compatible stem from any manufacturer will work. Handlebar will probably need to be replaced as well, same thing applies.

Bill Kapaun

IF it's between 1993 & 2014, you should be able to identify from these links. (they go back at least to 1987) Look at the various parts mix such as shifters, rims....
You can see how drastically different the stem is from early to late.
https://www.bikepedia.com/Quickbike/...k%20&model=820
https://www.bikepedia.com/Quickbike/...k%20&model=820

Notice at the left there is a box for "Years Made". Pick through that to narrow it down.

Shimano also date codes their parts.
https://bettershifting.com/frequentl...acturing-date/

Tonga

wow , that is a lot of excellent information.. Thank you very much. I think you have given me what I need to get moving on this.
I will let you know what I figure out..
thank you again

dedhed

On the older ones a good way to tell is also color scheme.
Trek Bike Models by Year and Color

wheelreason

That crackle yellow they came up with in the early 90s was hideous.

Tonga

OK it's a 2016 and I have the parts list I see parts on amazon that are the correct fit but I dont know anything about the quality. Does anyone know of these brands Fomtor? SanZhi?