Replace gearing of road triple on Trek 520.
 

The 1999 Trek 520 came with an 8-speed Shimano 105 chainring configuration of 52/42/30. This gearing is way too high for loaded trekking, even too high for enjoyable joyrides on some of the roads in my area with very long hills. After getting a new bicycle, just this year, I have a better idea of what kind of gearing this Trek should have.

I want something like 48/36/26 (the 26 is just what this config comes with - that ring will be replaced w/20 or something similar), with 70mm crank arms as well as a chainwheel guard.

The first option would be replacing just the chainrings. I've yet to find replacement 130bcd chainrings that surely have pins and ramps. I found a "Brompton" chainring in 50t that includes a chainwheel guard, but I don't know if it has pins and/or ramps, or what speed chain it's for, or whether "Brompton" means that it won't work with other types of bicycles or not. It says that it fits 130bcd. I'd be really happy if this worked for me, because of it having a chainwheel guard.

The next option is replacing the whole crankset. For 8-speed, I've found a Shimano FC-M361 Acera square taper crank. I would only get this if I can switch the 38t chainring to a 36t. Does the fact that Acera sits near the bottom of Shimano's line of "gruppos" mean that I should look for something different?

The next option is switching to 9-speed crankset. On the Harris Cyclery site, it says that the only thing I need for change to 9-speed is a new bar-end shift lever, a new chain and new cassette (2nd product down from the top - Dura-Ace 9-speed bar-end shifters). Would the reason it omits a new rear derailer be, that the idea is to use friction shifting instead of indexed?

I think that I might like to switch to 9-speed, if Harris Cyclery is correct, because then I could have a cassette that goes from 11 to 34 without any jumps bigger than 4 teeth. My Trek 520 currently has a "Megarange" cassette which goes to 34 and I hate the 8-tooth jump from 26 to 34.

For 9-speed cranksets I've found:
Shimano FC-M391 Acera Square-taper crank.
Shimano FC-T4010 Alivio Octolink crank.
Shimano FC-M4060 Alivio Octalink crank.
I don't really know anything about those two different types of fastening systems (Square-taper and Octolink), except that the square-taper is appreciated by a lot of people. Which is more worthwhile to have in this scenario, square-taper or, a higher level "gruppo"?

The next option is switch to 10-speed crankset. My 2020 Kona Sutra came with Shimano Deore FC-M8000/T6010. But like the T8000 crankset, I can't find it available for sale anywhere in the USA. The only places that I can find it for sale are in Europe and they, for some unknown reason, refuse to sell this particular crankset to customers outside of the EU.

Is switching to 10-speed even possible with this old bicycle frame and, is it even a worthwhile endevour, assuming that I'll have to get a new rear derailer in addition to all the other stuff like shift levers?

If I were in your shoes, I'd put on one of the nine-speed cranks you list and ride off into the sunset. Or the 8-speed Acera will work, too. No glamor, just a workhorse crank. That should get your gearing down where you want it, possibly paired with an 11-34 cassette.

Of course, you may need to swap bottom brackets to get the correct chainline. Still, that's pretty cheap.

Or if you want some blitz, get a Sugino triple crank. :)

If the cranks you are looking at are 130/74 bolt circle diameter, you might not get the gearing as low as you want, a 110/74 is a bit rare but they exist and the middle ring could go as small as 34. The five arm 74 bolt circle diameter will fit a 24, but nothing smaller.

My two derailleur touring bikes have a 24T granny gear, that with a 32T biggest sprocket in back gives me a lowest gear of 20.7 gear inches with a 700c wheel. That gets me up plenty of hills.

You could run a 9 speed crankset but keep your rear cassette at 8, thus not changing your 8 speed shifter. My derailleur touring bikes are both 8 speed, but one of them has a 10 speed crank. The crankset does not have to be an 8 speed one.

There is nothing wrong with square taper, all of my bikes except my road bike are square taper. Assuming your 520 is square taper, it might make sense to stick with it. If the new crankset is designed differently you might need a different bottom bracket to have correct chainline.

My most expensive bike, when I built it up I saw no reason to spend a lot on a blingy shiny crankset, bought one on Amazon for $35 and that was seven years ago, that bike is still working great with a cheap crankset. Do not worry about getting a lower end crankset.

The Shimano Deore 9-speed trekking crankset was replaced with 10-speed, and the current 9-speed crankset is found in the Alivio series.
The current trekking-triple Alivio crank is 9-speed, with Hollowtech II spindle and outboard BB compatibility. Stock rings are 48/36/26 with chainguard.
I would replace your crankset with this Alivio trekking crank and BB, and you could swap the inner ring with a smaller size if desired. Get a 9-speed 11-32 cassette or similar, and a set of 9-speed bar end shifters, and you will be all set. Very versatile and durable touring setup.

If you are going to use a mnt crankset on a 520 you will have to replace the bottom bracket with a shorter one to pull pull the chain line to 45-46 mm.

I replaced the cranks on my Bianchi Volpe with a 44/32/22 crankset. The drive train is: Sugino DX500 crank (square taper), 103 mm botttom bracket, 11-34 cassette, LX rear derailleur, Tiagra (9 spd.) 4503 front derailleur, Tiagra shifters. I have this or a similar setup on 5 bikes in our family, and it works great. The DX 500 cranks are no longer available. You can use a Sugino XD 600 which can give you a 46/36/24. It will work with 8 or 9 spd., and your present bottom bracket will probably work.

https://live.staticflickr.com/65535/...97fc52ce_b.jpg

General comment on 8 vs 9 speed. When I built up my first touring bike in 2004, at that time 9 speed was readily available and there were a lot of parts available for 8 speed too.

While the general philosophy of more is better always seems to make sense, I decided to look a bit more at the details of what a 9 speed would give me if I bought 9 instead of 8. I was looking at the 11/32 cassette size, and for comparison chose Sram cassettes. Both 8 and 9 speed cassettes had the same 11, 12, 14, 16, 18, 21, and 32T sprockets. The 8 speed cassette had a 26T while the 9 speed had 24 and 28T sprockets. I concluded that the vast majority of the time I would be riding on the 14, 16, 18 or 21T sprockets, thus it did not matter which I bought, 8 or 9 since both cassettes had the same sprockets that I would be using most of the time.

I am not saying there is anything wrong with a 9 speed, just that in my case I saw minimal advantage to it over the 8. In the 16 years since I built up that bike, I have built up 4 more bikes with the same 8 speed 11/32 cassette, chain, derailleur, etc. I currently have four bikes that share that same 8 speed drive train with 11/32 cassette, two touring bikes, a rando bike and a folder. That keeps my inventory of spares simpler to manage.

If you want to change to 9, go ahead, but if your 8 speed system functions well there is no reason to replace the shifter, cassette and chain. Just get a new crankset and likely a new bottom bracket to give you lower gears. I assume your front shifter and derailleur would work with whatever crankset you get.

If you are doing the work yourself, keeping square taper on the new crank means that you would need fewer tools than if you went with external bottom bracket bearings on the new crank. If you are not doing the work yourself, then cost of tools does not matter.

I would avoid the octalink cranks because of the limited choices of octalink BBs. And who knows what the availability will be on the future. Square was used so widely that it is no trouble to find exactly the spindle size you need at whatever quality level you want to pay for. Hollow tech compatible BBs arealso likely to be available in a range of options for quite awhile.

My Cannondale Quick CX has an Alivio-level crankset in front with 48-38-26 chainrings (I think.... but something close to that) and in back 8-speed Alivio 11-34. It gives me gearing down to 0.76:1 at the low end and 4.6:1 at the high end. I put a couple panniers on it with "commuter stuff" or other times a lot of groceries and head up the hill to home. On my ride home even from the closest grocery I have some 10% grades to climb. This configuration works out fine. I understand a loaded touring bike will be heavier, but I think this gearing ought to be adequate.

new Bromptons have a 130 5 arm spider, you could buy a triple middle, a tripleizer from TA French company with a 2nd bolt circle a 74pcd.. for a 24

You may also put a bashguard on in place of an outer chainring on a triple for a 1 by with a bail out low...
I sold my earlier generation Brompton crank/chainring to someone making a single speed ,
their earlier ones were swaged arm & chainring into one piece..





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Though you might be correct, I wouldn't avoid a crank set that I really liked because of the octo link bottom bracket. They're cheap so pick up a couple of spares, toss them in a drawer and you're set for a really long time.

You might consider going chain guard, 39, 24 on your current crank. Ramp pins are available on t.a. brand chain rings in that size last i looked. If your cassette starts at 11 teeth a 39 is plenty tall for the big ring. You can even make your current 52 into a chaingaurd by grinding off the teeth on a belt sander.

https://www.peterwhitecycles.com/ta-...s.php#ultra130

Go down the list. Peter white has middle ring for 130mm triple in 38,39,40,41,42,43 and 44.

I used a saber saw to cut off the teeth. Then put the ring on the crank and turned it by hand for maybe 10 minutes while holding a file on the cut edge to smooth down the rough cut. The aluminum clogged up one or two saw blades, but I had plenty so that was not a problem.

After the photo was taken, I sprayed it black to match everything else. This is on my Rohloff bike, thus no front derailleur, only a single ring.

https://cimg2.ibsrv.net/gimg/bikefor...49d869f7c0.jpg

FWIW, a better file the vixen file was created for the aluminum aircraft industry .

https://www.aircraft-tool.com/shop/d...ookieSupport=1

While a good idea, the Alivio is a poor choice. The rings are riveted in place which means they can’t be replaced. Nashbar currently has a Deore M6000 for about $95 without a bottom bracket (external ones are fairly cheap). It’s problematic because it has a 40/30/22 chainring set on it. A 48 tooth outer ring will cost around $30 to $40 to replace and a 36 tooth inner ring will cost $15 to $20.

Everything i have read lists the latest Alivio FC-T4060 crank as having replaceable chainrings with a 104/64mm BCD. I think that when the new Deore went to 10 speed, the Alivio line essentially took on the specs of the older 9-Speed Deore lineup, utilizing the Hollowtech II design and offering the trekking gearing. The pictures of the 48/36/26 option look to be built almost exactly like my 9-Speed Deore cranks on my touring bike, which i replaced the inner ring with a 24t, but a 22t could be easily sourced as well. I think this would be the most cost effective option.

If you are running bar ends now, I'd change to friction - I've always disliked indexed shifters, just one more thing to fool with which is totally unnecessary. Then you can run anything you want. I'd leave the crankset alone, but go 53-39-26 using Shimano 10 sp. rings, the 53 intended for a double, the 39 has to be for a triple, and the 26 can be anything with the right bolt circle. Then you can also run any RD and cassette you want, 8 or 9 speed. You'll need an 8 or 9 speed RD rated for your max cog. And a new chain of course. This is quite inexpensive and quick to do. Some people go as low as 24T on the granny, but seems unnecessary with the cassettes available. The 39 might be hard to find, but they're out there.

My mistake. Shimano list Alivio in both the “mountain bike” and “trekking” component lists. The FC-MT210-3 is the mountain bike version and is riveted. The FC-T4060 appears to be bolted.