Information

SHIMANO ROAD TRIPLES

Bolt circle diameter 130 / 92 mm: 

Bolt circle diameter 130/74 BCD: Shimano 105 Silver Triple 5703 10 Spd Chainset

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Yes Shimano sells 50/39/30 triples but the current 105 triple (FC-5700) has a 74 mm bolt circle for the granny so you can fit as small as a 24T granny ring in place of the 30. 

•  Differences: 50 - 30 = 20; 50 - 28 = 22; 48 - 28 = 20; 46 - 26 = 20.

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Road Triple Cranksets 130/74 BCD

Classic Touring Triple Cranks and Cranksets for Bicycles 110-74 BCD

http://harriscyclery.net/page.cfm?&PageID=49&Description=crankset

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Shimano FC-R563 triple, 50/39/30T - 105

Bolt circle diameter 130 / 92 mm

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To get a "real" Shimano triple road crank (130/74) in Hollowtech II you will have to find an FC-5703 (105) or FC-4503 (Tiagra) NOS as these aren't in current production.

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Shimano 105 Silver Triple 5703 10 Spd Chainset, Shimano, Shimano CHAINSETS ROAD

Definitely has the 74 ring

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http://www.sheldonbrown.com/harris/chainrings/74.html

74 mm BCD Chainrings from Harris Cyclery

We stock a wide range of chainrings for modern and older crank sets.

For more technical detail see the B.C.D. entry in Sheldon Brown's Bicycle Glossary

74 mm bolt circle (Full size MTB/Touring Triple, also "Road" triple.)

This is the standard small chainring bolt circle used with:

110 mm "touring" cranks, older mountain bikes, most everything that has a 46 or 48 tooth big ring.

130 mm "road triples" including Shimano Ultegra, 105, Tiagra, Sora. Although "road triple" cranksets commonly come with a 30 tooth small chainring, it is very easy to replace this with something more reasonable, such as a 26 or even a 24. If you go with a 24, you would also be well advised to add a chain deflector such as the N-Gear Jump Stop.

Using one of these devices allows you to set the low-gear limit stop loose enough to provde positive downshifting, without the risk of the chain overshooting and falling off inward.

This is by far the cheapest and best way to lower the gearing of a stock bike with a road triple crankset.

See also our options in custom cassettes.

This will exceed the official "capacity" of your derailers, but generally works fine with original stock "road" derailers as long as you don't make a habit of abusing the small chainring by running it with the smaller rear sprockets. See the"Capacity" entry in my Bicycle Glossaryfor an explanation of this.

24, 26, 28T

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Chainrings for 130 BCD

Sizes: 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 |52 | 53 | 54 |

ABOUT CRANKS (RIVENDELL): https://www.rivbike.com/kb_results.asp?ID=54

I was able to change my 105 triple to 50-39-24 and a 11-34 cassette, with the same chain and dérailleurs.

Works fine.

IF your 105 crankset is 110/74, not 130/74, you could use a 48/36/26 set-up. You could also use 48/38/29

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Front Derailleurs from Harris Cyclery

Double

Full SizedDouble

CompactTriple

Full SizedTriple

Mid SizedTriple

Compact

There are more complications involved in choosing a front derailer than with a rear:

Mounting

There are 5 different mounting types for front derailleurs, depending on the seat tube diameter of your frame, among other things:

• • 1 1/8" (28.6 mm) clamp on. (This is the traditional, standard type for most road bikes and older MTBs.

  • 1 1/4" (31.8 mm) clamp on for mildly oversized seat tubes.

  • 1 3/8" (34.9 mm) clamp on for oversized seat tubes, common on aluminum frames.

  • "Braze-on" units mount on a special slotted tab, which may be brazed, bolted or glued onto the frame.

  • "E-type" Shimano units have a bracket that is held on by the bottom bracket retaining ring. These also use a special braze on to stabilize the derailer.

Cable Pull

• • Traditional front derailleurs are "bottom pull", operated by a cable running up from the bottom bracket area to the derailer.

  • "Top pull" derailleurs are operated by a cable running down from above. This design is mainly used on mountain bikes, with the intent of avoiding running the cable under the bottom bracket, where it is exposed to spray kicked up by the front tire.

  • Some older designs use a loop of cable housing running from a stop near the bottom of the down tube. This design hasn't been used since the mid 1970s, but we stock a couple of derailer models that are compatible with this cable routing.

Large Chain Ring Size

Front derailleurs shift best when they are mounted as low down as is possible without having the cage foul the teeth of the chainrings. In particular, the bottom edge of the outer cage plate should be closely matched to the curvature of the largest chainring.

If you use a front derailleur with a larger ring than it is meant for, the rear of the cage will get too close to the chainring before the front of the cage is close enough to provide crisp shifting.

If you use a front derailleurs with a smaller ring than it is meant for, the front of the cage will get close to the chainring while the rear of the cage is still far away from it. This won't hurt shifting, but will require excessive "trimming" of the front derailer as you change gears at the back.

Mis-matched derailleurs/chainrings may be satisfactory with friction shifting, but will likely cause problems when used with indexed shifters, such as Shimano STI units.

If you have unusual gearing requirements, and are handy, you can re-shape the outer cage plate with a grinding wheel to match a non-standard large chainring.

Double/Triple

Modern derailleurs are optimized for either double or triple chainwheels. The shape of the shifting cage is tailored for the application intended.

• • "Double" front derailleurs have inner cage plates that extend down slightly farther than the outer plates.

  • "Triple" front derailleurs have extended inner plates that go down considerably lower than the outer plates.

"Double" front derailleurs will work with triples, but if the middle ring is much smaller than the big ring, they will be balky shifting up from the small to the middle chainring. They do, however, work well with "half-step-plus-granny" setups, where the middle ring is only 3-5 teeth smaller than the outer ring.

"Triple" front derailleurs may have interference problems between the extended inner plate and the inner chainring.

Indexing Road/MTB

The ratio of cable movement to derailleur movement differs with Shimano's "road" vs. "MTB" front derailleurs. This can cause indexing problems if you use a "road" front derailleurs with upright handlebars or a "MTB" front derailleurs with drop handlebars.

For more on front derailleurs, adjustment and troubleshooting, see my Derailleur Adjustment Article.