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What's The Deal w/55mm Cranks?

Lelandjt

adorbs
Apr 4, 2008
2,554
896
Breckenridge, CO/Lahaina,HI
When bikes had 135 or 142mm hubs we had cranks with whatever normal Q factor was and direct mount rings in whatever normal chainline was. When hubs grew to 148mm cranks stayed the same shape, BB axles stayed the same length, and chainrings got slightly different offset to sit 2-3mm farthe outboard. Last Summer I started seeing bikes like my Spark with "55mm" chainline cranks, or what Sram calls "DUB wide". So the chainring now sits farther outboard than a "Boost chainring"? And the Q factor is wider? The extra width (both Sram and Raceface) seems to be in the BB axle.

But why? What changed between '21 and '22 that made frame companies or crank companies decide we need our feet wider apart and our chainring farther outboard?

How did this slip by with no big product announcements or Pinkbike article?

Have any of you put a normal crank on a bike that ships with a wide crank?

I feel like this isn't universal for all new bikes. I think all the Santa Cruz and Ibis bikes I've built this year had normal cranks with Boost offset rings.
 
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Lelandjt

adorbs
Apr 4, 2008
2,554
896
Breckenridge, CO/Lahaina,HI
It’s all about Sram Transmission (in terms of companies producing compatible frames).
I considered this, but new Scott, Santa Cruz, and Ibis frames are Transmission compatible, while only the Scotts come with 55mm cranks (I'm talking non-Transmission builds). Transmission cassettes don't sit any farther outboard, do they?
 

djjohnr

Turbo Monkey
Apr 21, 2002
3,054
1,768
Northern California
I just listened to an old Chris Cocalis interview podcast where he was talking about super boost. The main goal there was to improve packaging around the BB, down tube and seat tube. "From a frame design standpoint, it is a game-changer. We can achieve a much better balance between chainring clearance, tire clearance, chainstay length as well as critical stiffness and frame strength in a critical area because of that additional 4.5mm that SuperBoost gets us over a standard Boost set up." Dub wide may be pursuing the same thing.
 

HardtailHack

used an iron once
Jan 20, 2009
6,952
5,950
So you can buy bikes that you can't just bolt some Saint cranks on and go ride? If so, that sucks.
I enjoy being a simpleton with a simple bike.
 

4xBoy

Turbo Monkey
Jun 20, 2006
7,090
2,994
Minneapolis
Cause, well as the French would say; Le F-U.

Your old cranks will still fit, but the chainring is not ideal, and it won't work with the new chains, probably.
 

SuspectDevice

Turbo Monkey
Aug 23, 2002
4,180
393
Roanoke, VA
I have a Trek Fuel ex gen6 that is spec’d for 55mm and 32tmax ring. When i tried it with a standard boost axle and a 34t ring(so i could run some saints from the basement and get decent mid range gears with Eagle), the chainstays flexed into the ring, point loaded and delaminated. Until the frame broke, the chainline, shifting and pedaling ergonomics were all much better for me than the setup that doesn’t break chainstays…

So, at least in some cases… specs matter.
 

HardtailHack

used an iron once
Jan 20, 2009
6,952
5,950
I have a Trek Fuel ex gen6 that is spec’d for 55mm and 32tmax ring. When i tried it with a standard boost axle and a 34t ring(so i could run some saints from the basement and get decent mid range gears with Eagle), the chainstays flexed into the ring, point loaded and delaminated. Until the frame broke, the chainline, shifting and pedaling ergonomics were all much better for me than the setup that doesn’t break chainstays…

So, at least in some cases… specs matter.
Can't you just use a chain ring with a bit of offset?
I think companies are still making them...
 

Lelandjt

adorbs
Apr 4, 2008
2,554
896
Breckenridge, CO/Lahaina,HI
On my previous gen Scotts a 32 ring cleared the chainstay okay but a 34 ring required me to space the crank over a little and/or run a ring with different offset from Wolftooth. So I guess this was done to improve clearance for bigger rings. Okay, good for me and the few other pros who like 34-38t rings. But I NEVER get customer bikes in the shop with rings bigger than 32 and NO bikes come stock with a ring bigger than 32. So kinda a weird move by the industry. I'm surprised they think this is worth the worse chainline in 1st and 2nd gear.
 

Dogboy

Turbo Monkey
Apr 12, 2004
3,210
597
Durham, NC
It’s all about Sram Transmission (in terms of companies producing compatible frames).
This is correct. And FWIW Ibis is speccing 55mm chainlines on all of their bikes - even though some still get delivered with 52mm chainline cranks. It's got to be a faster wearing setup on a boost rear end and I'm not a fan.
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
16,312
13,622
Don't quote me, but I think the Transmission cassette is slightly further outboard.
 

konifere

Monkey
Dec 20, 2021
577
716
If I am not mistaken, Chris Cocalis also said recentlier that with the downfall of PLUS bikes and the trend for longer chainstays, they did not need to have the 55mm chainline anymore and will spec 52mm chainline cranksets from now on. It's all fucked now.
BFY.jpg
 

Lelandjt

adorbs
Apr 4, 2008
2,554
896
Breckenridge, CO/Lahaina,HI
Installed Tranny on a new Ripmo frame a moment ago. Confirmed the Tranny cassette sits farther outboard than any other cassette. Tranny cassette binded on the UDH before it was removed and replaced with a Tranny derailleur.
 

djjohnr

Turbo Monkey
Apr 21, 2002
3,054
1,768
Northern California
If I am not mistaken, Chris Cocalis also said recentlier that with the downfall of PLUS bikes and the trend for longer chainstays, they did not need to have the 55mm chainline anymore and will spec 52mm chainline cranksets from now on. It's all fucked now.
Yeah, he said the big need was when plus became a thing. He also said that they tried to include SRAM in the Super Boost standard convo's but they were pissed off that someone was coming out with "super boost" when they had just come out with boost and wouldn't participate. So it looks like they just decided to create another "standard" even though super boost already exists.
 

Andeh

Customer Title
Mar 3, 2020
1,087
1,049
Chris Cocalis not only specs Super Boost but also PressFit, so I'm not sure I'd really consider his opinions really relevant to sensible standards. I'm just surprised he's not jumped on board with the headset cable routing yet.
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
16,312
13,622
Chris Cocalis not only specs Super Boost but also PressFit, so I'm not sure I'd really consider his opinions really relevant to sensible standards. I'm just surprised he's not jumped on board with the headset cable routing yet.
T47 headset with through pressfit BB cable routing coming your way!
 

Jm_

sled dog's bollocks
Jan 14, 2002
19,299
9,938
AK
Chris Cocalis not only specs Super Boost but also PressFit, so I'm not sure I'd really consider his opinions really relevant to sensible standards. I'm just surprised he's not jumped on board with the headset cable routing yet.
BB92, the worst of both worlds and the reason for Dub…
 

djjohnr

Turbo Monkey
Apr 21, 2002
3,054
1,768
Northern California
Chris Cocalis not only specs Super Boost but also PressFit, so I'm not sure I'd really consider his opinions really relevant to sensible standards. I'm just surprised he's not jumped on board with the headset cable routing yet.
He went over that in the podcast as well. Summarized - pressfit works fine if your tolerances are in spec, manufacturers just need to prioritize it as much as they do with headset spec. Still not a pressfit fan, but his explanation seemed sound.

 

Andeh

Customer Title
Mar 3, 2020
1,087
1,049
He went over that in the podcast as well. Summarized - pressfit works fine if your tolerances are in spec, manufacturers just need to prioritize it as much as they do with headset spec. Still not a pressfit fan, but his explanation seemed sound.

Even if it's possible to make the frame tolerances good enough that the frame/bearing interface doesn't creak like crazy, PF/BB92 sucks if you want to run larger diameter crank spindles. I know Pivot doesn't give a shit because they only spec Shimano, but if you happen to want to carry over, for example, a set of eeWings from your previous bike... have fun replacing the itty bitty bearings every few months. My buddy didn't think that through before he bought a different bike with PF, and is now firmly in team "Never Again PF."
 

Jm_

sled dog's bollocks
Jan 14, 2002
19,299
9,938
AK
Even if it's possible to make the frame tolerances good enough that the frame/bearing interface doesn't creak like crazy, PF/BB92 sucks if you want to run larger diameter crank spindles. I know Pivot doesn't give a shit because they only spec Shimano, but if you happen to want to carry over, for example, a set of eeWings from your previous bike... have fun replacing the itty bitty bearings every few months. My buddy didn't think that through before he bought a different bike with PF, and is now firmly in team "Never Again PF."
Pivot REALLY sucks because they knew all this and still speced the original 30mm spindle RF cranks on their bikes with totally insufficient bearings. This after they went to all this trouble to develop this 24mm spindle bb standard. And now we have F-ing Dub. Burn in hell.
 

konifere

Monkey
Dec 20, 2021
577
716
I hesitated long before buying my '20 Meta AM frame because it has a BB92, but when I received the frame, I measured the BB bores to make sure they were perfectly round and in spec, otherwise I would have sent it back. Good thing it was perfect.

Then I installed a HOPE PF41 bb that links the cups together by using a threaded sleeve inside joining both sides without rotating them in the frame (which seems better in my mind than the Wheels MFG and other who rotate the cups) and it's been silent since day one. But I had decided from the get go that I'd oly run Shimano cranks or the Race Face Aeffect R that I got for another bike. No 30mm axle sucks, but I prefer Shimano cranks anyway.
Hope-Press-Fit-PF41-bottom-bracket-review-100.jpg
 

Lelandjt

adorbs
Apr 4, 2008
2,554
896
Breckenridge, CO/Lahaina,HI
He went over that in the podcast as well. Summarized - pressfit works fine if your tolerances are in spec, manufacturers just need to prioritize it as much as they do with headset spec. Still not a pressfit fan, but his explanation seemed sound.

This is what I've heard from many engineers in the industry and matches my experiences with many pressfit frames, both good (Scott) and bad (Specialized).
 

Lelandjt

adorbs
Apr 4, 2008
2,554
896
Breckenridge, CO/Lahaina,HI
Even if it's possible to make the frame tolerances good enough that the frame/bearing interface doesn't creak like crazy, PF/BB92 sucks if you want to run larger diameter crank spindles. I know Pivot doesn't give a shit because they only spec Shimano, but if you happen to want to carry over, for example, a set of eeWings from your previous bike... have fun replacing the itty bitty bearings every few months. My buddy didn't think that through before he bought a different bike with PF, and is now firmly in team "Never Again PF."
On principal I'm not a fan of the small diameter and wish every PF92 frame was BB392* (press fit, same width, larger diameter) but in practice I've owned many PF92 frames, all with 30mm cranks and only experienced short bearing life in the Lightning BB. My Racefaces and Srams seem to have the same life as BSAs I've had, which for me means they never wear out with yearly regreasing.

*The one time I discussed this with a designer from a company that uses PF92 he said the larger diameter of BB392 would interfere with pivot placement and swingarm clearance.
 
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Gary

"S" is for "neo-luddite"
Aug 27, 2002
7,959
5,863
UK
Lizards sorted that out back when they phased out Square taper.
No modern BB lasts.
But really. Why 30mm? What do you imagine you're gaining over 24mm?
 
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Gary

"S" is for "neo-luddite"
Aug 27, 2002
7,959
5,863
UK
Nope. That's actually often where the corrosion damage is worst
 

Gary

"S" is for "neo-luddite"
Aug 27, 2002
7,959
5,863
UK
Nah mate. water ingress. from the repeated cycle of riding ~cleaning ~riding ~cleaning ~riding ~cleaning means corrosion often worsens when the bike is sat unridden. ie. go back to grab the bike for a ride find and the shitty poorly sealed BB stiff.
I live in one of the dryest parts of the UK (not saying much I know) and my sheds are water tight. But I keep all my most used bikes in the house anyway
 

toodles

ridiculously corgi proportioned
Aug 24, 2004
5,658
4,999
Australia
Nah mate. water ingress. from the repeated cycle of riding ~cleaning ~riding ~cleaning ~riding ~cleaning means corrosion often worsens when the bike is sat unridden.
You gotta skip the riding and cleaning part and go straight to the shed if you want shit to last. Plus the resale value is so much better and you don't even need frame wrap.