Ihmemies

Hi,

I have a BB with JIS taper, and my Velo Orange single speed JIS left crank worked itself loose over time. I installed the cranks in september 2022. I have not experienced anything like this before so during a bike trip I did not realize what was happening until it was too late. Apparently the left crank is now ruined and I need a new crankset, since velo orange doesn't sell individual cranks on their webpage. I had anti seize on the taper and had tightened the crank bolts to 40nm so I have no idea why it worked itself loose. Search results from the Internet provide tons of threads with the same problem with square taper left cranks, so I guess it's a common problem. Seems my only option is to buy a new crankset.

My rear chainline is probably (130mm/2)-((37.2mm/2)-4) -> 42.4mm. VO crankset has 42mm chainline and it has worked fine.

ROI cycles sells HT2 compatible Swiss bb's: https://www.roi-cycles.com/product-p...-hollowtech-ii

Does anyone sell 2 piece single speed cranksets with 42mm chainline, which do not use a square taper? There are tons of 24mm axle cranksets but they all seem to have a wider chainline

dedhed

Did you check with VO and see if they'd sell a L arm?

Does matching matter to you?
https://www.google.com/search?q=squa...t=gws-wiz-serp

maddog34

you put anti-seize on a taper fit.... you were worried about getting it apart in the future... it came apart on it's own... and much sooner than you were planning on.
did you tighten it until the bolt refused to turn any more, and did so with a long breaker bar?
you may have caused the arm to begin cracking.
the anti-seize didn't allow the two parts to remain stable, regardless of the torque applied.
taper-fits are SUPPOSED TO SEIZE to work correctly... that's the entire idea involved with the engineering.

use this as a lesson to prevent such failures in the future.

i have never had a crank arm work loose on the square taper bb.
i put them together after cleaning the tapers, smearing a small dab of axle grease around, then wiping most of it off.
i have never failed to get a crank arm off of a square taper bb that i put together as described.
i use a 3/8" craftsman breaker bar that is under 10" long, and i don't go crazy with it.
this technique has worked great...... for over 50 years.

i have replaced several cranksets that had the nut or bolt tightened to death by a suspected long breaker bar... and all were greased too heavily or had(yucko!) Anti-seize on them.
I've replaced a few BBs that had broken bolts or studs from WAY over-tightening a crankset.
and i've seen too many Crank arms that were deformed into failure .. they too were "greased"

Sigh.SMH, Facepalm, small tear.
@ 32 to 40ft/lb. torque................
if you don't know what that feels like, buy a torque wrench... get an old "Beam" type torque wrench... they're cheap, and last longer than most people will.

and Lay off the excessive grease or aunti-sneeze, ok?

Addendum.. 40 Nm equals 29.5 Lb/ft torque... AKA: too low... and click type torque wrenches vary dramatically... especially the cheap ones... We had the Fancy ones used for torquing Diesel head bolts and Crank/rod caps retested/calibrated regularly.. they vary too.
****this is a General message for you or Future readers... Most visitors look at past threads instead of signing up and all that fun***... and i'm sure a troop of others will want to argue the torque spec.thing to death.. i simply don't care. one may be the same one that stated that my automotive racing experience with Disc Brakes doesn't relate to bicycles because they are "totally different". Brakes convert Motion energy into Heat energy,.Period.

trashbiker

You could space the middle ring position on a triple. I imagine Hollowtech ii triples would be hard to find if they even exist. Those ifx cranks on ebay are compatible but I think they have mountain triple chainline.

Also a illegal tip you should use at your own risk: A bsa bb cup will thread into a swiss shell. I had an old tandem with french bb shells and I ended up chasing them with a bsa tool and using blue loctite on bsa cups. Its lasted a year despite the pressession issues so I'm qualifying it as a success. French thread pitch is the same as swiss, only difference is the thread direction on the drive side. If you're willing to take the risk, it would open up more options and maybe save you money. You'd probably need to get the tool yourself; no shop I've ever worked at would do this on a customer's bike.

I think maddog34's advice is best though. Square taper is very robust when properly installed. I'd probably stay away from velo-orange and go with something like sugino rd2.

jsdavis

Road doubles are typically 43.5mm chainline.

The 24mm axle cranks you are finding are probably "gravel" single cranks with 47mm chainline meant to be used on frames with 135m rear spacing. So the chain only moves 1.5mm outwards.

Kontact

Don't put anti seize on the taper. Take the arms off all bikes you did that to and clean them off.

grumpus

Well that's easy to answer - square taper cranks should be assembled dry.

kommisar

I have had a similar problem with a square taper crank. This was not caused by anything wrong with the square taper design but rather mischief of a would-be bike thief. I had my commuter bike locked outside a train station, sheldon brown style, with a small ulock around the rear wheel inside the frame. The would-be bike thief didn't have access to an angle grinder and so tried to use a leverage attack on the lock. My left crank arm was adjacent to a concrete lamp post base and when the thief tried to lever off my lock, managed to damage the socket on the left crank. After that day, no matter what I did, the left crank arm would loosen after 30 minutes of riding and fall off. I replaced the crank with another and fixed the issue. Sometimes I see left crank arms on offer on ebay, usually quite cheap. FInd one of the correct length and make an offer.

Broctoon

The SRAM S-300 is a very good crankset designed for single speed/fixed gear bikes. It uses the GXP bottom bracket and gives a 42mm chain line. The only complaint common to it is that SRAM's GXP bearings don't tend to last very long. The good news here is that they're cheap and easy to replace, and there are (expensive) alternatives offered by Chris King and Phil Wood that should last much longer. I don't know how wide of a range of chain rings are available in the 130 BCD that this crank uses.

Bike Gremlin

Based on my theoretical knowledge and practical experience, anti-seize is a good idea on square taper when installing the cranks.
Put some anti-seize both on the axle, and on the crank tightening bolt threads and its "face" as well. This will ensure that you are applying the 40 Nm of torque to push the crank up the taper and create enough preload, not to fight the friction of the axle, or the bolt itself.
(grease is OK also, it just doesn't provide a long-term anti-seize protection)

Left hand crank coming loose is a problem if it's not properly installed. Square taper has some other flaws, but left crank coming loose when installed properly is not one of them.

Regarding the chainline, if you measured correctly, it could be what you got, especially if you are using an 11 or a 12-speed cassette (otherwise, a common rear chainline for 130 mm OLD hubs is about 43.5 mm).

For 1x systems, it's often beneficial to have the front chainline be about 2 mm larger (further outwards) than the rear chainline (especially with wide-range cassettes - it helps prevent the chain from rubbing the adjacent sprocket in some gear combinations, even though it's less than ideal when using the largest sprocket of course).

Having said that, I'm not sure which 1x cranks use the 2-piece system and provide both narrow-wide chainring and a spindle short enough to allow for a 42 mm chainline. Maybe the above-recommended SRAM S-300 - don't know.

Relja

tFUnK

I second this. The S300 SS crank was like a poor man's Omnium for FGSS applications.

Kontact

You're wrong. The particulate in the antiseize is going to act like little ball bearings, preventing the tapered surfaces from getting traction on each other. Tapered cranks are held together by friction, not the bolts.

Bike Gremlin

I disagree.

Never had any problems when using anti-seize.

Also, as far as I understand the interface, it is held by preload, not relying on friction. Friction does keep the tightening bolt from loosening, sure, but with sufficient preload, bolts don't unscrew even when anti seize is used (otherwise, my bikes and motorbikes would not get very far).

Relja

Kontact

You are free to disagree, but you are disagreeing with people and companies with decades of experience that you don't have, and you misunderstand how fasteners work.

Bolts, screws, nails, rivets and nuts keep things together because they tension the two pieces being connected to the point that they are locked by friction to each other. If you built a house with loose screws/nails holding the studs together, the movement between the studs would break the screws off. Same thing with the lug nuts that hold your car wheels on. Fasteners are generally not strong enough to hold structures, just strong enough to provide the tension to create the structure.

On tapered cranks, the bolt creates the wedge fit between the crank and spindle, and then prevents that wedged fit from backing off. Antiseize discourages a wedged/interference fit, which means the crank keeps nudging the bolt. You'll note that crank bolts are normally just greased, so what happens is that the crank walks the bolt out until there is a sufficient gap between the spindle and crank for the hard steel spindle to destroy the soft aluminum - as the OP saw.



So I don't know what licenses you to ignore every manual and mechanic to issue your theoretical and limited practical experience as "advice", but you are just encouraging more people to break their expensive cranks. So I would invite you to keep your baseless bad advice to yourself. Tapered cranks have been in use for most of a century, and anti-seize on them has never been recommended.

Bike Gremlin

Quite rude - but I'd rather not waste time and energy further arguing.

Relja

Kontact

After years of trying to protect bike owners from bad advice, I've grown rather impatient with having to convince people with no practical knowledge that their bad ideas shouldn't be broadly shared along with good practices.

soyabean

That's your problem there.

Anti seize actually has some "thickness" it to, you were mashing in the sandy particles and grain of the anti sieze.

If you must use a lube, use something that will dry out completely like WD40.

Another problem is that your crank bolts may have had grease on them, or grease stuck into the taper threads. That must be clean clean clean bone dry, and locked with red permatex.

Your bolts did loosen eventually, and that gave play to the crank arm that rounded out your square taper.

Also, I think taper bolts are M8, and those can be torqued a little more to like 40 ft-lbs. You don't need specs if you don't exceed the max of any bolt's thickness.

Kontact

This advice won't break anything, but it is also not true. Tapers do not need to be degreased and thread locker is unnecessary.

Grease the threads, wipe the grease off the spindle and tighten. Recheck tightness after a few rides. That has worked forever.

SurferRosa

So, replace it with any other JIS tapered arm that is the same length as the drive-side arm.

After mounting it, don't try to ever retighten it. Ever.

Broctoon

That's what I've always done, and my cranks never come loose. NO grease on the "tapers" (spindle and square holes in the crank arms). A little grease on the threads of the bolts. Smoke them down TIGHT. Check after a few miles, and then never worry about them.

Kontact

Just to be clear, I don't think the tapers need to be degreased, just wiped off. A little rust preventative sheen of grease isn't an issue.

Ihmemies

Hello, sorry for the late reply. VO said they would send me a just left crank, so I guess this will be solved that way. They also recommended replacing the bottom brackcet just in case.

Also won't be using anti-seize with cranks anymore, only with pedals...

Kontact

You don't need it with pedals, either. Anti-seize just makes a mess.