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I picked up a used 2006 Trek 520 for pretty cheap as a project bike. This bike: https://archive.trekbikes.com/us/en/2006/trek/520#/us/en/2006/trek/520/details (specs are on that page).

I took it completely apart to get rid of some light rust in the frame and am going to get it powder coated. Once that's done I want to change the front chain rings but I'm not sure what the best route is. Currently they are 52/42/30. As a disabled rider (amputee, can't stand and pedal) living in a very hilly area, that doesn't really work for me. I'm wanting to install something more like 44/32/22. Perhaps something like this: https://www.modernbike.com/sr-suntour-xcm-sqr-crankset-3x9sp-175mm-44-32-22t-black-silver

I looked through the Shimano Archive for the 2005 line-up (https://productinfo.shimano.com/download?path=pdfs/archive/2005_LINE-UP_CHART.pdf) and specs (https://productinfo.shimano.com/download?path=pdfs/archive/2005_SPECIFICATION.pdf) and I believe that what I have to do is to change the front derailleur from the current 105 FD-5504-LB (triple, clamp, 63-66 degree chainstay angle) to the Deore LX version FD-M581/3 (triple, also 63-66 chainstay angle, dual pull). The rear derailleur is already a Deore LX RD-M570 SGS (long cage) and it has an 11-32 cassette. I believe the required capacity would be (44-22)+(32-11)=43 which is what the RD supports.

Note that the bike has Dura-Ace 9-speed bar-end shifters (SL-BS77) which would be set up for friction shifting on the front so I don't think that should be a problem. I realize I would also probably need to get a shorter chain and a different bottom bracket if I can't find a crankset that uses the current Octalink.

Questions:

  1. Is there something I'm missing or would this approach of using the Deore LX FD work?
  2. The Deore LX FD I'm looking for is no longer produced. I know I can find one used on eBay but is there a more modern FD that's still being produced that I could use instead? I can't seem to find any that would take a top chainring >40T and are 9-speed triples.
  3. Is there a smarter way to do this in general? Would I be better off going with 2x10/11 speed and a bigger rear cassette? My intuition says 'no' since I'm happy with 9 speeds and I can't see it being cheaper to swap out all the components vs just the FD and crankset. But maybe I'm wrong.
  4. Any other gotchas to look out for? It's my first time doing a frame-up build.

Thanks

2 Answers 2

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This was an era where the 52/42/30 cranks were specced often on the few touring/utilitarian road bikes on the market, despite being a bad match for them.

There are a few avenues that people go down in this spot. You've identified one of them, i.e. going to a mountain crank and FD. The others are stay with the existing crank and make the gearing as sane as 130/74 BCD allows, say 26/38/50. Adequate for some purposes but not others. Note that a piece of the puzzle that is easy now but didn't exist at the time is 11-36 9spd cassettes. Not all 9-speed mountain derailleurs can handle them, but if say your cranks were still good but your RD was borderline (as could easily be the case), this could also be a good direction - it depends on what you really want as a high gear, or in other words would the 50/11 be useful.

Many touring type riders have gone with the option of replacing the stock cranks with the various 110/74 options from companies like Sugino and Andel. For example, this can get you into 24/36/48 or 24/34/46. These combinations tend to still work adequately with road triple front derailleurs and a friction front shifter. Getting the more expensive ramped versions of the chainrings helps (this is a category where you have the choice in some cases).

There are some pros and cons to the notion of trying a more modern wide-range 2x or 1x setup of any gearing count (parts do exist to do it with 9-speed now). One major factor is that quality cassettes for those setups are more expensive, don't have individually replaceable cogs, and their no-range-to-spare approach encourages riding a lot on the small end of the cassette, which causes relatively more rapid cassette wear. They're also made of more expensive parts in general. In exchange you can get something lighter and in some regards simpler. This can also be an avenue to getting to a very low q-factor if that were needed.

If 3x9 is fine for you though and the 44t big ring type options are what you want for gearing, then going to a 104/64 mountain triple can make plenty of sense.

Many mountain 9speed front derailleurs past and present can do what you want in this case. Your bike will probably take either a topswing or traditional aka bottom-swing FD without issue, and in those cases the traditional will tend to be a little better-feeling (it's not a major factor though). The exception to this is that if the current road FD is just barely laying in between bottle cage bolts, then going to a mountain high-clamping traditional FD can cause it to want to land on top of the boss, so going to topswing can be needed in those cases. Shimano makes primarily low-end legacy replacements for 3x9 these days, like FD-M371 for traditional and FD-M2000 for topswing, but realistically either of those that fit given the above would be fine for many years if you didn't want to hunt for a vintage part.

You'll only be keeping your existing bottom bracket if whatever you come up with happens to want the same spindle length and/or type of BB. In most cases you'll be switching if you switch cranks. Of the various 104/64 triples you might come up with, many will want a mountain external BB, and some will want a square taper, Octalink, or ISIS bottom bracket of a given length (generally don't get ISIS for this application, but it's on the list of things you might find).

Touring bikes with 135mm rear ends will technically always want the standard "mountain" spindle choice for cranks like that. However, in practice you can typically use a shorter spindle without issue on a square taper or Octalink one, since the chainstays on bikes like that are so long. This can be a good choice to reel in the q-factor a little bit and bring it more into the "road" realm. The limiting factor will likely become the frame clearance with the big ring or potentially with the crank itself.

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  • Thanks for the detailed reply. You bring up some things I didn't think about. Regarding top ring, I really have no use for a 52. Nor a 50. 48 or 46 is probably the sweet spot but I am fine with a 44 as well. This bike is not being built for speed. Regarding q-factor, it sounds like switching to a MTB BB would be a good idea? Since this is my first frame-up build, my goal is to do this in the simplest and most "Shimano-approved" compatible way. So preferably not exceeding RD capacity even if it technically works.
    – Dan
    Dec 16, 2022 at 20:56
  • Another more expensive option I am considering is using the Deore-XT Trekking groupset: bike.shimano.com/en-US/product/component/deorext-t8000.html . I am not sure if the Dura-Ace 10-speed bar-end shifters would work with that rear-derailleur though. Also seems really hard to find from US retailers.
    – Dan
    Dec 16, 2022 at 21:15
  • @Dan I edited my answer to address the BB question. In your case, for the 105 cranks listed as stock, you presumably have an Octalink v1 BB that is not compatible with almost any mountain triple crank you might find. Generally speaking all you're going to do is choose your crank, and then choose whatever BB is listed as the normal or default option if it's a mountain triple. Dec 16, 2022 at 22:25
  • The XT trekking cranks would work and then you would just use any of the Shimano mountain external BBs. You may need to tune the ring spacing with teeny chainring spacers under the small and large rings to work with 9-speed without the chain rubbing. That is a change you could make later if needed, and it's not a big deal - you just buy 8 of the Wheels Mfg 0.6mm chainring spacers and slip them in, then re-adjust the FD. Dec 16, 2022 at 22:28
  • Very good info, thank you. I need to spend some more time researching and seeing what I can find. In my earlier comment I was actually referring to switching the entire groupset (FD, RD, crankset, etc) to the Deore XT Trekking version. It would be pricey but it would be the modern version of how I'm looking to set up the bike. Would a 10-speed cassette fit on a 9-speed rear Deore LX hub? But it's also good to know that it might be an option to use a 10-speed crankset with a 9-speed derailleur. Most likely though, I will get a mountain triple, a mountain FD and BB.
    – Dan
    Dec 16, 2022 at 22:39
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For a 44/32/22 crankset, you'll need a 3x9 MTB Front Derailleur. Current Altus line-up does have such front derailleurs. Or, you can buy LX second hand; but LX is nothing special. Some tourers like it, but it's just Deore level stuff, effectively. By replacing the crankset to an MTB one, as 44/32/22 is MTB specific, you' re also changing the chainline, but will work unless you buy very fancy, new cranksets meant for MTB's with bigger chainline. I'd suggest buying 3x9 Deore from eBay. They are robust, easy to live with, quite light and cheap. Also, chainrings can still be found, at least on eBay and AliExpress.

Going 10 speed is OK with friction shifters. I advice you to change pulleys on your rear derailleur to 10 speed ones, like this one: https://loveforbikes.com/gt3_gallery/shimano-grx-rd-rx-400-pulley-set/

9 speed crankset will work "meh" with 10 speed groupset, but you have to adjust front derailleur incredibly precisely - otherwise chain will drop between chainrings, and get stuck.

Let me know if you have further questions, and I admire you,sir.

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  • Thanks for the reply. Regarding friction shifting, I would only use that on the front, not on the rear derailleur. Not sure if that was clear. As mentioned in the other comment, I'd prefer everything to be "compatible" and designed to work together so nothing works "meh". Any specific suggestions for 3x9 Deore derailleurs?
    – Dan
    Dec 16, 2022 at 21:02
  • There is no compatible new Deore front derailleur now; as current Deore is 10-11s. However, you can still buy new-old stock Deore's, or Altus, if that's unavailable. This will work, as it's top pull compatible: bike.shimano.com/en-EU/product/component/deore-m610/… Dec 17, 2022 at 14:13

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