I currently have a Zee chainset that’s running an oval 32t AB ring.

From what I have read it’s unlikely to fit my new frame that is “boosted” 🙁

I would need to forgo the oval ring as it’s already offset but could I just run a 104bcd chainring in the outer posistion to help clear the chainstay?

NO …  The Spindle is the wrong length.

You have a 640 (68/73) the Boost is a 645.

I’ll swap you if you like … seriously I happen to have a Zee Boost (645) not being used.

I’m away for a week from tomorrow AM then back and away for another week so let me know if you are in a rush!

Edit: Its 170mm crank length BTW

So how does a longer spindle work in a 73mm shell?

I thought the “boost” bit was down to the chainring for direct mounts and the spider dishing or 4bolt etc.

Not seen mention of spindle length anywhere 🤔

So how does a longer spindle work in a 73mm shell?

It doesn’t … if you look at the Zee Cranksets there is  640 and a 645.  The spindle part is pressed in and not changeable (without a huge press)

The 640 is a spindle for a 73mm “shell”… so if you used with a 68 you’d want 5mm total spacers

http://www.chainreactioncycles.com/shimano-zee-m640-10-speed-chainset/rp-prod82416?gs=1&sku=sku319010UK&pgrid=39252756840&ptaid=aud-111606983596:pla-142933416288&utm_source=google&utm_term=&utm_campaign=Chain+Reaction-UK-PLA-PLA-All-DT-SE-Shopping+QLB+Product+Desktop&utm_medium=base&utm_content=mkwid%7Csb6QICfRU_dc%7Cpcrid%7C161850334074%7Cpkw%7C%7Cpmt%7C%7Cprd%7C319010UK

The 645 is for the boost “shell” so its 83mm

http://www.chainreactioncycles.com/shimano-zee-m645-10-speed-chainset/rp-prod82417?gs=1&sku=sku319012UK&pgrid=39252756840&ptaid=aud-111606983596:pla-142933416288&utm_source=google&utm_term=&utm_campaign=Chain+Reaction-UK-PLA-PLA-All-DT-SE-Shopping+QLB+Product+Desktop&utm_medium=base&utm_content=mkwid%7Csb6QICfRU_dc%7Cpcrid%7C161850334074%7Cpkw%7C%7Cpmt%7C%7Cprd%7C319012UK

“theoretically” you could stick 15mm of spacers on a 645 but chain line would be way out … but you can’t go the other way even ignoring chain line as the spindle is not long enough… it wouldn’t go into the NDS crank.

The NDS cranks are identical… they are labelled M640/M645 its basically only the spindle that changes.

Ermmm 83mm BB is not boost related. It’s just a wider BB found on DH bikes usually.

OP, if your new frame is standard 68/73mm BB you should be able to adjust your chainline by spacing the chainring or moving BB spacers.

Err,ahem,…..I’ve just built up a boost frameset and used my old crankset (pre boost) , I only realised a week ago that boost cranks were available, result, chain line isn’t noticeably bad, and never dropped a chain, I’d say, give it a go, but others on here won’t…..

Just try it, your chainring will either foul the chainstay or not…

Yep that 645 Zee is indeed for an 83mm shell and nothing to do with boost.

My BB is 73mm so I guess adding a second spacer to the DS it would cause an issue with the NDS crank attaching …. Thinking of the lawyer hole in the spindle of a Shimano crank.

I understand that 30t is doable with a non boost chainset but that’s problematic in 104mm format 🤔

Where im going with this is could I just run a chainring on the outer posistion ….. Its stay clearance rather than chainline that immediately concerns me!

LOL M640 and M645 are nothing to do with Boost / Non Boost – it is to do with shell width.

Boost chainsets chainline is 3mm wider than non boost to make up for the wider rear end. You can get away with running a non boost chainset on a boost frame but the chainline will be slightly off. Alot of people run this with no noticeable issues, its gonna be down to your specific set up / chainring size.

If you run the ring in the outer position, that is more than 3mm extra, maybe if you left off a spacer on the drive side it might get it back to a boost like chainline.

But the recess for the bolts would be on the wrong side so you would have to reverse it and the angle of the ovality would be a bit off.

I just changed my non Boost chain ring (6mm offset) AbsoluteBlack oval to the same in Boost (3 mm offset) and that was it.

Sometimes you will get say with changing nothing depending on frame clearance etc.

You can get away with running a non boost chainset on a boost frame but the chainline will be slightly off.

Actually, it’ll be better.  The boost chainline shift is about clearance, rather than improving chainline.  Assuming we’re talking 1x, if you’ve got enough clearance to run a non-Boost chainset then do it.

See: https://www.wolftoothcomponents.com/pages/boost-chainline-and-chainrings

The ideal boost chainline is actually ~49-50mm if you have adequate chainstay clearance and don’t run plus-sized tires.  This means that in most cases the current Wolf Tooth Drop Stop (TM) chainrings are perfectly suited for Boost rear hub  bikes.

^^

As above.

My chainline was better with the non Boost but frame clearance was minimal unfortunately.

Fitting non boost depends on your frame. I have done it on my Sonder Transmitter but I have boost on my Chameleon.

thread resurrection

I have a non boost  raceface aeffect crank, can I just fit a boost chainring to make it work OK in a boost frame?

Just fit as is firstly as it might be fine.

If not then you should be able to fit a Boost find to give you the extra 3mm clearance. I don’t have the Aeffect crank,I have the Turbine but should be the same/similar I would think.

Running non boost cranks on SC Bronson 2 – no probs at all

Looking at buying the Sram NX1 eagle 1×12 but it aint boost and its going on a Boost frame will I get away with it?

Rich

Aeffect and other cinch cranks the boostness is in the ring offset not the arms so just swap ring.

Looking at buying the Sram NX1 eagle 1×12 but it aint boost and its going on a Boost frame will I get away with it?

Rich

Nah, you’ll almost certainly burn in hell… Can I watch?

+1 if the (non-boost) ring clears the chainstay okay then a (non-boost) chainline is often better than a boost chainline, on a boost bike. If that’s all clear.

Put another way, you only need a boost ring if you need chainstay clearance.

Erm, curiosity… what’s a Boost? Besides the nice chunky chocolate bar…

148mm rear hub, rather than 142.

110mm front hub, rather than 100.

Can I hijack this-

Been looking at some SRAMM carbon cranks and the non-boost ones can be had at significant savings.

Am I right in thinking the arms are identical and you could just buy the non-boost cranks heavily discounted and fit a boost chainring and they will be identical?

@chilled76, Not 100% about SRAM’s own chainrings (expensive anyway) but yep there are definitely rings (AB etc) that will let you boostify a non boost SRAM crank.

The issue is all about chainline, non boost was 49mm and boost is 52mm. It’s not a universal fix as obviously it’s up to the chainset designers if they choose to put the 3mm offset in the tabs, ring or add some spacers.

I run non-boost cranks with 32t in my SOlarisMAX LS.
Clearance and chainline are fine. For some boost frames, non-boost actually gives you a better chainline.

Give it a go with your current setup before wasting money.

I was just looking at Santa Cruz historic stuff a few days ago working out how old my old Chameleon was and noticed they said the bike was designed for a 50mm chainline (although the old chams were slot dropout proper SS friendly which may have bearing here). So possibly it is worth checking the frame manufacturer agrees with the drivetrain manufacturer about how things should be installed… (unless there’s some arcane 8/9sp thing I’m missing there)

I’m also running non-boost cranks in a LS Solaris Max, with a 34T and no probs, so as suggested, try wat you’ve got first and see how you get on.

I run standard non boost slx cranks in a boost frame (surly KM) just fine. I tried it with all 3 rings fitted and the big ring (42) fouled the chainstay, so I removed the big ring and it works just fine.
The answer in all cases, if you already have the cranks then try it and see, you might save a few quid.
Personally, I’d wrap the rings in a cloth to avoid paint or carbon damage, as it would annoy the life out of me to damage a frame before it’s even been ridden.

Isn’t part of the picture dependent on if you have a boost rear wheel or not, rather than the frame?

I’ve just moved my non boost chainset and non boost rear wheel (from a Codiene) to a boost frame (Pace RC129). All i had to do was use the velosolo (via ebay) spacers on the rear axle and disc and everything has worked perfectly. I just needed to adjust the limiter screws on the rear mech – that was it!

A lot of the time it’ll fit, but it might not as the chain line and crank will be 5mm inboard on the non-boost version.
FWIW I put a non-boost ring on my gf’s bike and it works fine, probably better in fact as the chain line is more central on the cassette and better aligned with the lower gears that undoubtedly get more use.

I’m running an Absolute Black non-boost chainring on my “boosted” SC Hightower LT and have plenty of clearance – however back pedalling causes the chain to jump a little when on the 10T sprocket – from memory using the original boost chainring made the drivetrain pretty noisy on the 50T sprocket

Anyone else found anything similar?

One reason chainline is set slightly outboard of the centre of the cassette is that, if it is too far in, you get graunching when in the smallest cog like you say @yoshimi. (That is according to something I read from either Wolf Tooth or One-Up.)

I noticed it when running a spaced-in One-Up ring on a spider for an old school triple, so quite a few mm further inboard than the standard non-boost chainline, with a boost spaced cassette. Not just when back-pedalling, when pedalling also. That was between the 11 and 13 on a Shimano cassette.

Bloody minefield the so called cheap drivetrain just got more expensive as the cranks use a Dub bottom bracket and you need a special tool to fit!!!!

If you go too far inboard with the chainline then when on the smallest sprocket the chain will catch on the second smallest. Apparently this is more of an issue on 12sp.

I’ve gone 4mm inboard of “normal” on 11sp, and it’s not an issue, and is noticeably better on the larger sprockets.

FWIW, the chainline on SRAM’s road 1×11 stuff is much closer to the centre of the cassette (and is better for it).

But the road cassettes only have a 1 tooth gap at the small end, making it less of a problem?

Rich – I have one you can borrow

Great now I know who you are YOSHIMI