Subcompact options-bottom brackets

[marciero]

Considering MarkMcm's SRAM Force 22 road subcompact set up discussed in the thread below. Would likely use with Engin spider with TA rings. Frame is a used-to-be standard BSA/English threaded 68mm bb. The SRAM site lists Force 22 as available in both 24 and 30 spindle, while CC simply lists "GXP" as spindle. Other vendors also dont seem to list options for spindle size either for the cranks or for the GXP bottom brackets. What are my options for bottom brackets? Probably buried somewhere on PL but could not find this below. Thanks in advance.

https://forums.thepaceline.net/showthread.php?t=232810

[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!

[R3awak3n]

as far as I understand, sram has 2 systems...

BB30 which is a 30mm spindle and GXP which is a 24mm spindle. On a BSA system you can use either. GXP you will need a GXP bb, the BB30 you will need a bsa 30mm bb like a rotor or something like that, there are a few (don't think sram has any that would work, this is kind of a hack but works fine).

So you can pick either crank, the GXP is a bit heavier but might not matter to you. I like the BB30 one better because will work with more frames, more future proof.

[NHAero]

I did Mark's hack with a Wheels Mfg. product for GXP.

Threaded Road ABEC-3 BB for 24/22mm Cranks (SRAM) - Gray

[marciero]

Thanks all. So it seems the SRam route would be straightforward.

Regarding Angry's remarks-

Am vaguely aware of some of the newer options. I actually have the Shimano GRX on my gravel/camping bike-cheap and awesome. On the other hand, I did not know WI had an outboard bearing version of the VBC. For this bike I have stronger preferences for the low Q, and also the 44/30 ring sizes. It appears the WI has 156 Q which is about like the GRX. Even the ST VBC is 150 Q.

The MarkMcm/SRAM/Engin route had 146 Q but also had the option of TA 5-arm rings, which to me is an advantage. On the other hand, would rather have alloy than carbon...

The Sugino OX 901 would really be what I am after, but aside from the expense, they only seem to be available from Japan and would take like a month to get here. (I broke a spindle on my OX 601 version of these which gives me pause but I think there may have circumstances leading to failure). There are also some crankarm-only versions of the 601 that seem to be available.

I suppose the simplest thing would be to just get another GRX. would not even need to change the BB on the bike.

Edit: Now looking at the Easton... low-ish Q at 149...

[ColonelJLloyd]

I've been using the the Q156 GXP version SRAM XX 42/28 and XX FD and RD for nearly three years now and have been extremely happy. BSA shell. Shifters are Red 22 hydraulic and everything works beautifully together.





My buddy just converted his Force22 crank to 42/28 using an XO GXP spider and rings. He had to grind down the chain peg to the right length, but was otherwise plug and play from what I understand. Finding the right spider took a little time. His bike also has a BSA shell. His drivetrain is otherwise Force22 hydraulic.

[unterhausen]

SRAM changed the spider on the better road cranks, because why not? I went to the lbs to see what arms I could get for the older style spider, and it was only low-end stuff, so I bought used.

I think I would have purchased a GRX if I had to do it all again and didn't find what I wanted used. I'm a lot happier with Shimano BB, the SRAM GXP bb are expensive and my experience with their longevity has been poor

[jtbadge]

If you have rim brakes/130mm rear spacing, the Shimano GRX crank will push your chainline outward and cause extra chainwear when using the larger cogs. I went Praxis 48/32 on my rim brake all-roader.


Also intriguing is this 46/30 set (seen on eBay from "bikinGreen") that mounts to standard 110bcd 5 bolt crank arms.

https://www.instagram.com/p/B85VM4llWz_/

[NHAero]

Mine is on my Litespeed drop bar conversion, and I'm running XO GXP 42-28. spider and rings off eBay. Crank came with the 110 BCD spider. The set-up is such that the 135 rear hub with a Shimano 11-40 11s cassette and Ultegra RD8000 on a Wolftooth puts the 42T ring roughly in the center of the cassette in terms of chainline, which is optimum because I use all 11 cogs with the big ring.

[robt57]

Originally Posted by ColonelJLloyd

My buddy just converted his Force22 crank to 42/28 using an XO GXP spider and rings. He had to grind down the chain peg to the right length, but was otherwise plug and play from what I understand. Finding the right spider took a little time.

I can attest to this setup. I got the 28/42 rings on the spider, so mounting that to the CX1/Force arms was simple, pin shortening required as mentioned. I am using a FD-R8000 [rear R8000GS] and bar cons [indexed carbon microShift] for gravel bike. Almost never use the 28 really. But 11-40 rear without additional hanger drop device needed. I have an 11-42, but not tried it as the 40 is already very low, and not actually use the lowest gear out on the bike yet. other than to test range off bike stand etc.

I also have on another pair/bikes both 5800 and 6800 with 30/46 after market 7075 rings similar to absolute blacks.

The CX1_28/42 was totally plug and play and shifts better by a lot. But you kinda sit in the big ring and only drop for serious climbs. So not than big a deal, but I prefer the SRAM setup. It is not a post engineered add hoc, and it shows in shifting performance.

The 30/46 setup chain line had to be diddled, the SRAM totally plug/play. Wound up with a wavy washer drive side on the 30/46 setups to get the chainline usable.

Re: GXP BB on BSA, not big fan due to what I consider porky. But have a CX1 on two Trek BB90s where your just use the Non drive bearing with a 22mm ID, that without the GXP BB is quite the nice solution for the anti-pork crowd [me].

FYI: the Force carbon arms are nice low Q-factor, there-fore I have had situations where a generous chainstay width frame was either too close to use comfortably, or even hit.

And 30/46 rings referenced: eBay: bikinGreen CNC Road Chainring 46/30T BCD For 4 Arms Shimano 9-11 Speed

CX1 28/42 pic

[ColonelJLloyd]

Originally Posted by unterhausen

I'm a lot happier with Shimano BB, the SRAM GXP bb are expensive and my experience with their longevity has been poor

Hmm. They're at most $30.

[unterhausen]

Okay, I'm cheap and they wear out every year for me.

[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.

[ColonelJLloyd]

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 shipachped, 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.

I would not be interested in a 20t jump. Pretty sure that would throw off my "one shift with each lever" solution to dealing with rollers.

[marciero]

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.

That was mentioned in a 2017 thread that I almost linked to in my OP. If you search "subcompact" in titles only it will come up. But I think it was only mentioned. I wound up ordering the Easton AC90-thanks Nick for calling that one out-and 46/30 direct-mount rings and Race Face BB for a complete proprietary matchy-match.