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  1. #1
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    disc brake adapter for '99 Trek 8500 LT

    I've got a '99 Trek 8500 LT and want to put a disc brake on the rear. It has 22mm disc caliper mounts on the Chain Stay. Does anyone know if there is an adapter that will allow you to use a 51mm caliper. I have heard different things...some say you have to use a 22mm Hayes hydraulic disc brake, and some say there is an adapter that will allow you to use any 51mm caliper. I have a 51mm mechanical disc brake that I would like to be able to use. Any info would be much appreciated. Thanks!

  2. #2
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    Ummm...I used to have a 99 7000...

    Quote Originally Posted by buhastings
    I've got a '99 Trek 8500 LT and want to put a disc brake on the rear. It has 22mm disc caliper mounts on the Chain Stay. Does anyone know if there is an adapter that will allow you to use a 51mm caliper. I have heard different things...some say you have to use a 22mm Hayes hydraulic disc brake, and some say there is an adapter that will allow you to use any 51mm caliper. I have a 51mm mechanical disc brake that I would like to be able to use. Any info would be much appreciated. Thanks!
    and one of the reasons that I got rid of it is that there was no way to use a 51mm brake on it. There is no adapter that will work. If you look carefully at the positioning of the mount on the frame you will notice that it is on the chain stay, not the seat stay like most bikes!!! It was designed specifically to direct mount a hays 21mm caliper. Being on the chain stay, there isn't enough room to get an adapter and caliper in there. Why Trek did it like that I have no clue. The 2001 bikes had the mount moved to the seat stay (even though they were still the 21mm direct mount) but the position allowed for an adapter to be used. Trek used to sell those too. Granted the mount set up on the 01 bikes were marginally stronger than the "normal" tabs that were used by the rest of the industry, but they weren't all that! And in some cases set up a harmonic vibration between the frame, caliper and adapter that would raise the hair on the back of your neck. You usually only hear howls like that in B horror flicks. The reason that there are those that say there is an adapter that you can use is that this set up was only used for 2 years and is not that wide spread now. Most people don't remember it or don't even realize that they were made that way. Anyway you can't use a "regular" caliper on that frame. If you can find an old 21mm hayes caliper you'll be in business, but other wise....

    Good Dirt

  3. #3
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    I have the same bike

    I got it at the end of '98 and upgraded to a rear disc brake in early '01. I have a direct-mount Hayes caliper that I got real cheap (at the time) from my LBS that I am assuming is a 21mm. From the sounds of it, I'm glad I got it when I did. The location of the caliper mount is less than ideal, as I have screaming fits every time I replace the pads and try to re-align the caliper to stop that awful rubbing.

    Good to see someone else still riding an 8500 LT. Black and red, I presume? I have replaced just about every part on this bike. The Judy 100 fork that came on it lasted about 2 years before it was replaced with a Marzocchi and the list goes on. The concept behind that bike was odd - kind of like an all-purpose hard-tail trail bike - but a great bike nonetheless. One of the first mass-market hardtails w/ a long travel fork and disc brakes, I believe.

    Upgrading to f/s this winter, but will keep this bike around for smoother trails.

  4. #4
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    Quote Originally Posted by Mike679
    I got it at the end of '98 and upgraded to a rear disc brake in early '01. I have a direct-mount Hayes caliper that I got real cheap (at the time) from my LBS that I am assuming is a 21mm. From the sounds of it, I'm glad I got it when I did. The location of the caliper mount is less than ideal, as I have screaming fits every time I replace the pads and try to re-align the caliper to stop that awful rubbing.

    Good to see someone else still riding an 8500 LT. Black and red, I presume? I have replaced just about every part on this bike. The Judy 100 fork that came on it lasted about 2 years before it was replaced with a Marzocchi and the list goes on. The concept behind that bike was odd - kind of like an all-purpose hard-tail trail bike - but a great bike nonetheless. One of the first mass-market hardtails w/ a long travel fork and disc brakes, I believe.

    Upgrading to f/s this winter, but will keep this bike around for smoother trails.


    It has been a great bike, and I have put it through so much. I rode it really hard for about 5 years and bought a new bike last year. I was moving and the 8500 was taking up too much space, so I stripped it. Now I am building it back up for my brother to use. Now almost everything on it will be new, so I am ready to get back on it and see how it rides. I guess I'm gonna head to the shop to see what kind of brake system can be found to fit this frame. It seems like such a weird idea, putting the caliper mount on the chain stay, I haven't heard of many other bikes that were built that way. Thanks for the input.

  5. #5
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    My Klein Attitude also has the small Hayes caliper mounted on the chain stay, probably the same setup as your Trek. According to my local Klein dealer, Hayes still makes that size caliper in the HFX Mag style. He had some there at the shop so I got one and put it on the bike. It's easy to put on and not that big a deal to adjust the positioning if you have some patience. If your Trek dealer doesn't have it, try your Klein dealer, or contact Hayes directly. The dealer told me Hayes still make it but dont list it and you have to ask for it and order it. Good luck with it.

  6. #6
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    adaptor

    Try 'a2z components' I think that they do an adaptor that fits this chainstay disc mount and then allows you to fit an int std caliper - make sure you have the smallest brake you can as clearance can be a little tight - but it works!!

    I actually got a local machine shop to make me a bracket to fit a int caliper for about £50 for my old 99 Mantra - but you need to produce a V.V Accurate drawing and measurement's.

    Hope this helps mate

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