Subcompact options-bottom brackets

[robt57]

FWIW, the Force is highly configurable. I bought 3 sets NIB old stock for 99.00 each with 110 spiders no rings. Sram spider pulls and even new on eBay with and without rings abound on the cheap.

#2 is setup with Oval Rotar 36/53 rings for road, and #3 Red 34/50 rings for road.

As I said above, the GXP version used in BB90 frame with no GPX BB is a great light setup.

[Mark McM]

Originally Posted by rccardr

Anyone here have experience with the IRD Lobo subcompact system? External bearing, 24mm, 110/74, five bolt, come in both silver and black. Recently picked one up online for around $190 shipped, intend to run it as a 50/30 with an 11-28 cassette. Will give me a climbing range close to 34/34, but without the gigantor big cog, which I find less pleasing to the eye.

From what I can see, the IRD Lobo system is very similar to the Sugino OX_01 subcompact cranks, except that the Lobo system has a wider chainline & Q factor. This means that the OX_01 system is more optimized for road bikes, while the Lobo is more aimed at gravel and fat tire bikes.

The Sugino OX_01 and IRD Lobo chainrings appear to be interchangeable.

[Mark McM]

Originally Posted by AngryScientist

marciero,

i know i'm not answering your question directly, but before you go too far down the rabbit hole...

that thread was started before there became available a slew of new, off the shelf subcompact options, and you may be better served by buying something in stock-ish configuration.

easton has a subcompact setup in both their carbon and alloy cranks now

same for rotor

GRX shimano has subcompact available

WI in both ST and outboard BB configuration

finally, absolute black makes subcompact rings for standard ultegra cranks.


point being, unless you want to modify a sram crank, there are new options available that may be easier.

sorry for the non-answer!

As you say, there are now multiple options for subcompact cranks. However, most of these new options offer only slightly smaller chainrings - typically down to only 32 or 30 teeth (as compared to a minimum of 33 teeth for 'traditional' 110mm compact). Engin spider allows chainrings down to 24 teeth, and the XO spiders allows chainrings down to 26 (120/80) or 22 (104/64). Another advantage of the Engin spider is that they use very common BCDs (110/74) for which there are a wide variety of chainring sizes from a large number of manufacturers.

[rccardr]

Originally Posted by Mark McM

From what I can see, the IRD Lobo system is very similar to the Sugino OX_01 subcompact cranks, except that the Lobo system has a wider chainline & Q factor. This means that the OX_01 system is more optimized for road bikes, while the Lobo is more aimed at gravel and fat tire bikes.

The Sugino OX_01 and IRD Lobo chainrings appear to be interchangeable.

Yep, noted the slightly wider Q but am less sensitive to Q width (and crank arm length) than some other riders, perhaps because my collection has such a wide diversity of cranksets. Intend to mount this on an italian threaded BB on a road bike with 30mm Vittoria Graphenes; it will be interesting to see where the final chainline falls. Generally a big fan of running the inside ring as close to the chain stay as possible and working from there. Since the crank shaft os wide enouh to mount on either a 68 or 73mm bottom bracket (68mm uses a supplied spacer), my assumption is that I can use various thinner spacers on each side to get it where I want it. We shall see.

The reason for a subcompact when planning this buildwas to wind up with a bike that had a wider range of gearing that was applicable to the kinds of roads actually ridden. Around here, with a 50 tooth (or a 48) big ring, I can ride pretty much anywhere without using the inside ring. A 30 inside ring makes it easier on some of the rides with more elevation like Southern Wisconsin, Skyline or Thunder Ridge while using a 28 big cog out back. Swapping to a 34 big cog makes it a double with gear inches low enough for Cino or Eroica.

At least...that's the plan.

[kingpin75s]

Originally Posted by marciero

Even the ST VBC is 150 Q.

150mm Q for a chain line of 47.5 on a 113mm SqT BB. A fine chain line in my experience with running a lot of these but not strictly standard for a road double.

If you are looking for lower Q and this is for a 130mm rear spacing road bike, you could drop to a 108mm BB for a 45mm chain line and a 145mm Q. Want to get you chain line even closer to a road 2x at 43.5mm then drop down to a 104mm BB for a 43mm chain line and offset if 0.5mm if you choose.

All assumes you can clear the rings at your chain stay. Referenced standard length Phil JIS BBs available in my examples.

[marciero]

Originally Posted by kingpin75s

150mm Q for a chain line of 47.5 on a 113mm SqT BB. A fine chain line in my experience with running a lot of these but not strictly standard for a road double.

If you are looking for lower Q and this is for a 130mm rear spacing road bike, you could drop to a 108mm BB for a 45mm chain line and a 145mm Q. Want to get you chain line even closer to a road 2x at 43.5mm then drop down to a 104mm BB for a 43mm chain line and offset if 0.5mm if you choose.

All assumes you can clear the rings at your chain stay. Referenced standard length Phil JIS BBs available in my examples.

These are good points, and one forgets the role of the bb spindle in the world of outboard bearings and two-piece cranks. I went ahead and got the EA 90 crank as a quick and dirty, moderately priced, plug and play-along with the Race Face
Cinch bb bearing. Going to install, I notice the bb is 68/73, with spacers for 68. Something about using spacers when you dont need them and the point is low Q does not make sense. I may be sending these back and going square taper after all. Or, the Sugino which has over a month delivery time on ebay and seemingly unavailable elsewhere.