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Old 01-05-10, 05:43 AM   #1
RayB
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Trek 520 Fork Replacement

Hi,

I need to replace the fork on my 520 and thought it would be great to replace with a disc capable fork. Most decent ones I can find are 1 1/8". I thought the 520 would of been the same but after pulling out the current fork it appears to be a 1" fork.

Probably a stupid question but is it ever a possibility that you can buy a new headset that would get the 1 1/8 fork to work with the 520. I assume it would just be thinner bearings in order to do this.

Otherwise I have to try to find a 1 inch disk capable fork. I want to figure this out before I order the one I really want as shipping is expensive down here to Tokyo to make a mistake.

Many thanks!
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Old 01-05-10, 07:13 AM   #2
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I recently looked into changing the fork on my Trek 520 to equip it with a disc brake, but soon gave up on the idea.

First, I don't believe there is any way to get a 1 1/8" fork into a head tube designed for a 1" fork.

There are a few forks with 1" steerers that can take a disc brake, but the fork on most Trek 520s has a lot more rake than most after-market forks. The steering response on the 520 is already very slow because it is designed for fully-loaded touring, at which it performs very well, but changing to a fork with less rake will slow the steering response down even further, which will make it EXTREMELY sluggish when riding unladen.

If anyone out there can offer a good option, then I'd be keen to hear about it, but I didn't find anything very suitable.
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Old 01-05-10, 07:26 AM   #3
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I'm doing the the same mod. I bought a Dimension cyclocross/disc fork with 1" steerer. It has 45mm rake, your 520 might have 50mm rake, the lower rake will make the bike more stable, less responsive. On my 72* HT angled Schwinn, I prefer the less rake. It's just slightly different but better IMHO. There's no threads on the Dimension fork, you'll have to change over to a threadless headset or have some threads added to the Dimension fork:

http://www.universalcycles.com/shopp...5&category=704
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Old 01-05-10, 02:04 PM   #4
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I thought the same thing about getting the fork in there. What makes me wonder is that I have found references to the 2004 and 2009 Trek 520s coming with 1 1/8 headsets. Mine is a 2008 and cant find any references to headset size but didnt think they would of changed it just for that year and then gone back?? So, with a little luck maybe the headset they used in my model year compensated for the size in some way bringing it down to 1 inch.

That Dimension cyclo fork may be the best option.

Thanks,
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Old 01-05-10, 02:11 PM   #5
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Quote:
Originally Posted by RayB View Post
...What makes me wonder is that I have found references to the 2004 and 2009 Trek 520s coming with 1 1/8 headsets....
Opps, sorry, I'm an old fart, I thought you meant the early eighties 520. You can get that fork in either 1" or 1 1/8" steerer. I assume your Trek has a modern stem and 1 1/8" threadless headset, for that it's easy, buy the 1 1/8" fork and a starnut, cut steerer to lenght, install and enjoy.
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Old 01-05-10, 07:07 PM   #6
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Hi Mr IGH,

Thanks again for the reply. I understand I can get that fork in both sizes. But the thing that I am finding strange and perhaps didnt explain to well is that the specs I find on the web before and after that model year state the frame comes with a 1 1/8 headset from factory. But, in fact when I pulled out my fork, the touring fork that came with my 2008 Trek is a 1" fork. So, I am curious if Trek just installed one of those headsets that can reduce the size from 1 1/8 to 1". So, in the end I am wondering if I can simply go out and get a 1 1/8 headset to work with the fork that I really want.

I dont understand why bike makers just cant list all their specs on their websites. They seem to have no problem dumping pretty pictures and marketing garbage up there.

Oh well... guess the only way is to pull the sucker out and measure.
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Old 01-06-10, 01:50 AM   #7
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I've seen it discussed on here before that although the official steerer size for most recent Trek 520 model years has been 1 1/8", many of the smaller frame sizes came with 1" steerers. This was the case with mine, it's a 2002, and the specs say 1 1/8", but the steerer is 1". There doesn't seem to be anything special about the headset because I changed it a couple of years ago from the stock loose-ball headset to a new cartridge headset, and a regular 1" headset did the job just fine. There's a chance that your 2008 version is different, but I think it's pretty unlikely.

That Dimension fork is one of the few decent-priced options that I found, but the low rake put me off. As I said, I already find the 520's steering very unresponsive, and would not want to make it any more so. If you can find anything with a longer rake, then I'd take that instead, even if it doesn't have disc brake tabs.
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Old 09-22-11, 04:05 AM   #8
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I have a 25" (XL) 2002 520 and it also has a 1" headset, even though the specs list it as 1-1/8". Mine came with a 1-1/8" Bontrager stem with a shim to fit the 1" steerer. I assume all the 520s have 1" headsets.
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Old 09-22-11, 09:58 AM   #9
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Yeah, Trek used 1" on the 520 for quite a while there. RayB, if you want disc capabilities, you might want to just get yourself a Surly LHT Disc frameset, transplant your parts (other than headset) and then sell off your 520 frameset & headset.
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