Low q, low range 2x cranks

[Adam]

Hi all,

Adjacent to the triples thread, I'm thinking about moving away from a triple to a double in order to get a lower Q.

What are options for double cranksets that are around 40/26 or so? I think that would be doable with the Rene Herse cranks, but too much $$$ for me. Are there any cheaper options that will do that and give me a q in the 140s?

Second, drivetrain stuff is a little new to me. What determines how small a q factor a specific bike can have? I'm assuming chainstays play a role here? This hypothetical project is for a Hillborne, so I'd be curious what folks have used to get low q on their Hillbornes. I'm assuming I may have to change the BB as well.

Thanks!

Adam

[Irving]

Behold, the nerd crank database!

I ordered the La Dixna cranks from AlexsCycle and matched them with TA Chainrings for a 42/26 wide low double. Have been really happy with that combination.

-Irving

SF, CA

[Ron Mc]

Hi Adam, 

take a look at VO Rando crank.  

If you can find them, Sun XCD makes their 50.8 BCD and chainrings, which I'm running on 2 bikes.  .  

I was on SJS Cycles last night looking at rings, and noticed they still have some T/A-5 chainrings.  

[Ron Mc]

adding a ps - another use of your triple crank, there are some virtually weightless bash guards out there if you want to make it a compact double.  

[Adam]

Thanks,

Great ideas already. I have thought about the VO cranks, but want slightly lower gearing if I'm going to the trouble of swapping.

For Ron, or anyone else, does swapping the large ring for a bash guard allow for a lower Q? I assumed that would stay the same?

I'm going to look at the Alex cycle option, your pic is exactly what I want to do. Is there a clever way to piece something like that together from older stuff on eBay? Guessing it may take knowledge I don't have 

Adam

[Bill Schairer]

Since you stated you are a bit new to all of this, I am curious as to exactly why you are so focused on a lower Q?

Bill S

San Diego

[Josiah Anderson]

Uhh... because lower Q works better for some people? That's like asking why someone wants a longer/shorter stem...

Adam, with the VO cranks (if we're thinking of the same ones) if you can get a set of arms without rings, TA rings will fit, which are available in any tooth count down to 26 IIRC. 40/26 is definitely possible with the TA 50.4bcd rings. You could also watch eBay etc for used TA cyclotouriste/pro 5 vis cranks, which is what the VO and SunXCD cranks are copies of.

Josiah Anderson 

Missoula MT 

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[J G]

Adam,

Regarding:

does swapping the large ring for a bash guard allow for a lower Q? I assumed that would stay the same?

No, in fact this would create a higher Q if implemented properly.  Chainline is now between middle and small rings with a bash and need longer BB spindle to achieve proper chainline, resulting in higher Q.

The best use of triples for low-Q doubles are ones where the granny ring has spacers that can be removed.  Cranks like the old Ritchey Logic and Suntour XC Pro (among others) can be run with middle/large rings only and a shorter BB spindle for proper chainline between middle and large in this implementation and lower-Q.

[Bill Lindsay]

Adam asked: "What determines how small a q factor a specific bike can have?"  

In my view it starts with chain line, and a 135mm OLD rear end like a Hillborne "expects" a 47.5mm chain line.  For a bike like that, getting into the 150mm range is pretty good.  Bikes with a 130mm OLD "expect" a normal 43.5mm road chain line and give you a lower floor if you are looking to minimize Q-factor.  I'm kind of Q-factor obsessed, and I maintain a number of 126mm OLD bikes just to facilitate that.  I also have a 120mm OLD custom in the works with an ultra-narrow 41mm chain line to go even narrower.  That machine will end up in the low 130s in Q-factor.  

A lot of people with 135mm OLD Rivendell Road bikes will set up their double with 43.5mm chain line anyway, thinking of it more as a 1x plus granny setup.  Swing the whole cassette in the big ring and only use the larger 4 cogs in the small ring.  Doing that would probably bring <150mm Q-factor into play for your Hillborne.  

Bill Lindsay

El Cerrito, CA

[J G]

This one is a little harder or more restrictive as you cannot use a middle/outer combo for a 94bcd double/triple with the 26t and requires the use of the granny ring for most triples, which works against low-Q:

What are options for double cranksets that are around 40/26 or so?

White Industries VBC road cranks is what I tend to use for doubles in the range of 24/38 up to 28/42 and the Q is not quite in the 140s but a flat 150mm on a 113mm BB.

-Justus

Mpls, MN

[Ron Mc]

Of course I come from low-Q, T/A Cyclotouriste and Strada 

Use of parts-bin low-q Strada crank on my daughter's x9 '86 Team Fuji frame required some special attention, including swapping the embosed-cage stock Spirt FD for newer, flatter Ultegra. 

The crank arms couldn't clear the embossed FD cage on the big ring.  

Old-sck T/A Cyclotouriste crank arms on my Lenton could just be made to clear the Simplex chain guard I wanted to add.  While I made this work, I preferred the slightly flared Sun XCD version of these crank arms, 

On Wednesday, January 10, 2024 at 12:09:37 PM UTC-6 Josiah Anderson wrote:

[J G]

Bill,

As a fellow Q nerd, this is a really good mention:

A lot of people with 135mm OLD Rivendell Road bikes will set up their double with 43.5mm chain line anyway, thinking of it more as a 1x plus granny setup.  Swing the whole cassette in the big ring and only use the larger 4 cogs in the small ring.  Doing that would probably bring <150mm Q-factor into play for your Hillborne.  

If I do not set a perfect chainline on a 2x bike, it is always skewed to the inside for reduced Q and shifting habits as described above.  Although, I generally run a 108mm vs. 113mm for WI VBC as an example so I generally only go from 47.5mm to 45mm chainline and 150mm to 145mm Q.

-Justus

Mpls, MN

[Bill Schairer]

"That's like asking why someone wants a longer/shorter stem..."

Which could be a perfectly valid question to someone who has stated he has limited knowledge of such things.  The reason for the goal may determine the method of achieving it.  If the person I actually asked the question of takes offense, I apologize.

Bill S

San Diego

[Adam]

I tapped the right place for info!

The nerd crank database is EXACTLY what I was looking for. And Bill, Justus, thanks for clarifying the chainline stuff. I think I get it, though I'm not sure if I understand what BB will get a specific chainline, I'll ask that question once I get farther along figuring this out.

I do intend to run it as a 1X + granny. Realistically, where I live, the chances of using the granny are non-existent, but I love climbing and on the rare occasions I travel to bike, want the option.

As far as WHY I'm interested in changing, I have an IRD defiant 46/30 on another bike and I'm finding that I MUCH prefer that feel to the wider stance on the Hillborne. I don't know for sure the exact measurements, but I think the IRD is around 150 and the current triple I have on the Hillborne is 160+

thanks for the info. I'm going to poke around that database later.

Adam

[Nick Payne]

Sugino OX series. Very nicely made and attractive cranks that use 110BCD for the outer ring and 74 BCD for the inner, Q factor 145mm. For some reason they aren't sold with a smaller chainring combination than 44/30, but you can use them with smaller chainrings than that. Here's one I installed on one of my wife's bikes with 39/26 chainrings. The downside of the cranks is that they're rather expensive - a cheaper alternative of the same design with 110BCD for the outer chainring and 74BCD for the inner is the Dixna La. It's about one third the price, and also slightly narrower Q, though to my eye it's also less attractive: https://alexscycle.com/products/dixna-la-crank-arm-set-130mm-to-170mm.

Here's the Sugino OX801 - on Sugino's website it has now been superseded by the OX901, which looks pretty identical.

Nick Payne

[J G]

Adam,

Re:  "...though I'm not sure if I understand what BB will get a specific chainline"

That will be crank and implementation specific.  

Since this is Riv-centric we can use the concept of a square taper triple mountain crankset as an example.  It will require a specific BB length to achieve the proper chainline for the standard implementation, which in this case is 47.5mm for 135mm rear spacing.

I you want to:

 - Run as a double and rm granny, then reduce spindle by 6mm (mountain double/triple and preferred single speed 47.5mm chainline)

 - Run as a triple on a bike with 130mm rear spacing, then reduce spindle by 5mm (road triple 45mm chainline)

 - Run as a double and rm granny plus run on a 130mm rear road spaced bike, then reduce spindle by 11mm (and yes, for some cranks, you cannot find spindles that small)

 - Run as a double with bash, then increase spindle by 6mm

-Justus

Mpls, MN

[Kim H.]

Awhile back, I wanted to have some ultimate "granny gears" as absolute insurance for climbing hills without spending a lot of money. I came across the Avid Micro-adapter 74/58 bcd granny gear adaptor for a 20T ring. 

After sometime of playing around with it and getting a lot of advice from over on the IBOB LIST (https://groups.google.com/g/internet-bob/c/-C-kw8MfM2Y/m/xW5gSLXUAgAJ), I succeeded in doing so.

These are my results. I have a Rivendell 52cm Clem Smith Jr. "L" bicycle with a the standard SILVER 173mm crank set with rings of 34/20T with a SunRace 9 speed cassette 11-40T in the back. My front derailleur is a Shimano CX70 and my rear derailleur is Shimano Deore RD951 9 speed SGS long cage with a Wolf Tooth Road Link. This set-up works very well for me for my cycling needs, after years of running a triple crank set. The last one I ran was a 172.5mm T. A. Zephyr 42/36/20T. I don't feel the need to run a triple anymore.

There is nothing like having a lot of low gears and plenty of water bottles and cages to hold them. One never knows where my adventures will take me.

How low can you go ?

Kim Hetzel.

[Kim H.]

I used a Rivendell chain guard for the outer 110bcd and placed the 34T ring on the inside of the 110bcd. The Avid Micro-adpater is placed on the 74bcd for the 20T ring.

Kim Hetzel.

[Beth Hamon]

An easy DIY affix with basic parts, new or used. I swapped a thin chain guard for my outer ring, installed a 38 in the middle and left the 28 granny alone. Works fine with my refurb’d Suntour 5sp freewheel, and didn’t cost a fortune.

Beth H in Portland

[Bill Schairer]

So, for example, the old TA Cyclotouriste cranksets, which are known for having a low Q, were designed when the rear ends were maybe 120 or 126 for use on frames that could maybe take 32mm  or so tires.  The stays didn't flare out from the bottom brackets as much as a lot of modern bikes built for 135mm rears and accepting wider and wider tires.  Compromises, compromises, you may find that a Hillborne just can't accept a Q of 150 either because of chainring clearance or crank arm clearance.  I don't know. How much clearance do you currently have on your Hillborne between the end of the crank arms and the stays?  How much clearance between the chainrings and the chain stay?  You can go out and buy a narrow Q crank and find that you have to mount it to a longer spindle than it was designed for in order to get the necessary clearance or desired chainline putting you right back where you are now?

I don't know if pedal spindle lengths are standard but maybe there is a pedal out there or replacement spindles out there whereby one can bring the pedals inboard a few mm?  For my wife I had to buy pedal extenders to move her pedals out because she was clipping her ankle bones on the crank arms.

Bill S

San Diego

[Nick Payne]

Middleburn (now BETD) also make what they call an Incy spider, which uses 110BCD for the outer ring and 58BCD for the inner, so you can get down to 20t on the inner ring. But it's not all that low Q at 153mm with 44mm chainline. They used to make the spiders for both their RO1 and RO2 cranks, but now they only have them for the RO2 cranks.

Here's one I have on an RO2 crankset with 38/22 chainrings fitted.

Nick Payne

[RichS]

This has been a good refresher course on q factor. It has also been fun "window shopping" so many nice looking crank arm and chain ring setups.

Thanks everyone!

Best,

Rich in ATL

[John Hawrylak, Woodstown NJ]

VO has a 50.4mm BCD crank in 46-30, but you can use TA rings to get what you want.   Their spec is a 144mm Q on a 116mm symmetric BB with a 43.5 FCL (per email from VO).   However, John Thruston in AK told me he achieved a 141.5mm Q with a 110mm BB, indicating the VO spec is 3.5mm optimistic (the crank should have a 138mm Q with a 110mm BB).  The VO is $200, but they have 20% sales so you can get it at $160. 

Sun XCD is 50.4 with a Q spec of 145mm with a 113mm BB & 43.5mm FCL and can be had with TA rings from Jitensha Studios for about $290.   This is about the same $ as the VO sale after buying TA rings in other than 46-30.   I thought the SunXCD was the better deal and the optimum cost/benefit for a low Q double with low gearing.  The SunXCD specs are from a SunXCD drawing shown on Santucci Cycles site after selecting the crank in their Shop.

As Bill L stated, your Sam is a 135mm OLD, so a 43.5mm FCL puts the Outer ring closer to the middle cog, so the Inner ring should not use the smallest cogs.  This should not be a problem if you watch your shifting.

John Hawrylak

Woodstown NJ

[John Hawrylak, Woodstown NJ]

On 10 Jan Adam asked:   "  I'm thinking about moving away from a triple to a double in order to get a lower Q." 

One option is a 1980's Sugino AT (110/74mm BCD) set for a double, say 46-33, sicne 33T is the smallest 110mm BCD ring out there,  e.g. TA Zephyr on Peter White's site.  The AT was designed as a low Q triple.

*  I have achieved 152mm Q with a Tange 127 cartridge BB and 2mm drive side spacer for a total asymmetry of 6mm, very close to the D-3U Sugino recommended.  The Outer ring FCL is 45mm and the Inner ring FCL is 37mm with a 43.5mm RCL.

*  Others on the I-Bob list have stated 147mm Q. 

The AT Inner 74mm BCD ring uses very very low posts cast in the spider & 5mm spacers instead of higher cast posts using no spacer.  The Middle 110mm DCB ring protrudes further inward than the 74mm holes.  Therefore, removing the 74mm Inner ring and spacers creates a double with the Inner ring chainbolt head being the limiting clearance to the chainstay.

The double has a Q of about 145mm with a 46-36.    The only problem with a 110mm double is the smallest 110BCD ring in 33T.   However, with a 12-36 9 speed cassette, a 46-33 is 1 gear higher than a 46-30 for a No Load low gear (24.1gi vs 20.4gi with 584x38).  

EBay seems to have a decent supply of AT's, I bought 2 a year ago, a 1980 and 1984 one.

So unless you need the very lowest No Load low, a Sugino AT as a double may work. 

John Hawrylak

Woodstown NJ

On Wednesday, January 10, 2024 at 11:15:06 AM UTC-5 Adam wrote:

[Adam]

Thanks for all the help everyone!

I definitely appreciate the V.O. cranks more now that I've seen the alternatives. I am still mulling it all over, but it seems like buying those and swapping the rings may be the thing for me.

FWIW, I've come to prefer more compact cassettes for the FLAT riding around Chicago. I replaced a 11-32 with a 12-27 and much prefer the new setup, mostly because wind is so constant. Realistically, I'll never use the smaller chainring here, but want it for potential travel.

Thanks!

Adam

[John Hawrylak]

Adam

You might want to verify with VO about the actual Q of their 50.4 crank.  They list a 144mm Q with a 118mm BB.  I exchanged emails with one member on the iBob list using the VO 50.4 crank and measured a 141.5mm Q with a 110mm BB.   This would indicated the Q stated by VO for their 50.4mm crank is lower than actual 5mm  141.5 + (118-110) = 149.5 vs a VO claim of 144.   A 149.5mm Double is not quite low Q.

John Hawrylak

Woodstown NJ

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