[Gary]

Do Saint crank arms have more material around the pinchbolt/spline area than an XT or deore arm?

I ask as since HTII came along I have used pretty much nothing but Saint crank arms and had very little problems with them. Recently I've been riding a couple of bikes with XT HTII and another with shimano non series HTII cranks.
What I'm finding:
The XTs need the pinchbolts re-tightening from time to time. (No biggie but I never have this problem with Saints)
The L/H non series crank actually worked its way off the axle while riding and ejected itself taking the plastic pre-load bolt out with it. All were torqued correctly when installed and have the plastic spacer in the pinchbolt gap.
I've replaced the arm with carbon paste on the splines, replaced the pre-load bolt with an alu one and torqued the pinchbolts as tight as they'll go with the spacer in but am not super confident it's going to stay put.

Any input on this appreciated.

Cheers.

 

[Udi]

Remove the bolts, preload cap, everything else.

Clean out all the grease, if there's a lot of gunk it's better to use oil first to dissolve the grease and then detergent or degreaser to remove the oil, followed by isopropyl if you want to be safe.

Use blue (242, 243) loctite on the bolt threads , and if problems continue, switch to red (262, etc) loctite.
You should alternate between the bolts numerous times while tightening.

Also, are the cranks second hand? If they've come loose once - even just being subjected to the events you describe - it's possible (in fact likely) that permanent damage has been done to the splines which will make it harder to get a proper install ever again.

The correct lube for the splines is a light coat of grease (making sure it doesn't get near the threads), certainly not carbon paste because particles will hinder proper clamping torque in the interface.

 

[Gary]

.

Thanks Udi.
Yeah/ I already cleaned everything . I know how to fit/torque pinch bolts
Nothing is secondhand but a few of the bikes are used by others (work bikes)
The crank arm that came off is 5 weeks (300miles) old and it's on one of my bikes. Only ridden by me.
Carbon paste was kind of an experiment. I'm not so sure about your opinion on not using it seeing as I'm attempting to create more grip between the spline and the crank. I thought it was worth a shot. The crank arm splines do have slight damage. I'll blue loctite the pinch bolts too. A new l/h crank is the next port of call if it doesn't stay put.
The work bikes are regularly bolt checked/serviced so like I said it's no biggie for those (I was more using them as an example)

Any idea if Saints actually do have more meat where it's needed? (Ie, less flex/clamp the spline more securely) I suspect flex may actually be part of the problem here allowing the arm to 'walk' off the spline.

 

[6thElement]

Any idea if Saints actually do have more meat where it's needed? (Ie, less flex/clamp the spline more securely) I suspect flex may actually be part of the problem here allowing the arm to 'walk' off the spline.

Yes, Saints are deeper than XT's with a wider clamp area.

I discovered it when I needed to replace the spacer safety thing with the small pin, bought an XT and it wasn't wide enough, pin however transferred to the Saint spacer thingy no problem.

 

[Gary]

Yes, Saints are deeper than XT's with a wider clamp area.

thanks.

 

[kidwoo]

Yes

 

[HardtailHack]

Also agree with Udi about the carbon paste.

 

[Gary]

View attachment 128932

How much experience do you have with loctite 660?
is it a liquid metal filler? or an adhesive?
If used on crank splines how easily would the crank arm come off again? and how difficult is it to get the loctite off the axle spline to fit a new crank arm? (the axle splines are not damaged)

 

[Wuffles]

Hey! Someone else who has popped Shimano crank arms off!

Sprained my ankle pretty bad when my circa 2012 XT NDS arm came off out of the blue. Pinch bolts were loctited (blue, not red, guess that's what I get for using the weak stuff). Sold them and have never run a crank without positive retention ever again.

 

[Gary]

Hey! Someone else who has popped Shimano crank arms off!

Sprained my ankle pretty bad when my circa 2012 XT NDS arm came off out of the blue. Pinch bolts were loctited (blue, not red, guess that's what I get for using the weak stuff). Sold them and have never run a crank without positive retention ever again.

Did yours also have the STUPID plastic pre-load bolt?

Luckily both times it's happend to me I've felt it while sat down pedalling rather than anywhere rowdy.

I actually pulled an old headset headlock out of a spares drawer and was contemplating how to modify it to go through the hollow axle. Hmm... i wonder... does anybody make such a thing?

 

[Wuffles]

Did yours also have the STUPID plastic pre-load bolt?

Luckily both times it's happend to me I've felt it while sat down pedalling rather than anywhere rowdy.

I actually pulled an old headset headlock out of a spares drawer and was contemplating how to modify it to go through the hollow axle. Hmm... i wonder... does anybody make such a thing?

Why yes, yes it did. After thinking about it in the several weeks off the bike I was forced into, it really started to piss me off. Actually, it still fucking pisses me off. The entire crankset is basically designed on the hope and prayer that the pinch bolts don't come loose- which is an hideous warpage of the correct usage of pinch bolts.

 

[StiHacka]

Did yours also have the STUPID plastic pre-load bolt?

Luckily both times it's happend to me I've felt it while sat down pedalling rather than anywhere rowdy.

I actually pulled an old headset headlock out of a spares drawer and was contemplating how to modify it to go through the hollow axle. Hmm... i wonder... does anybody make such a thing?

Get an aftermarket alloy preload bolt and you won't drop the NDS crank again.
The plastic one is stoopid, 100% agree.

 

[rideit]

Did yours also have the STUPID plastic pre-load bolt?

Luckily both times it's happend to me I've felt it while sat down pedalling rather than anywhere rowdy.

I actually pulled an old headset headlock out of a spares drawer and was contemplating how to modify it to go through the hollow axle. Hmm... i wonder... does anybody make such a thing?

 

[Gary]

Get an aftermarket alloy preload bolt and you won't drop the NDS crank again.
The plastic one is stoopid, 100% agree.

Yeah. I've now fitted an alu one I had in a spares box.

Hmm.. Yeah. You can't be too careful.

 

[toodles]

If your pinchbolts are loose enough for the crank to come off the end of the axle, then it will strip the spline first hard landing and fuck the splines anyway. Get a metal preload bolt if it adds confidence, but all that will do is stop you losing the crank arm on the side of the trail. It would be like installing a headlock to keep your stem on so you didn't have to tighten the pinch bolts.

 

[Gary]

The pinchbolts weren't actually very loose at all @toodles
Probably read through what I've already said and what i'm asking. I'm actually trying to figure out HTF it's managing to slide off.

FWIW The problematic crank is a Shimano E8000.
If it were possible I'd have thrown them in the bin and fitted Saints. Unfortunately that's not an option (for obvious reasons). Shimano make an E8050 but it just seems to be an XT hollowtech (the E8000 isn't hollow)

 

[toodles]

The pinchbolts weren't actually very loose at all @toodles
Probably read through what I've already said and what i'm asking. I'm actually trying to figure out HTF it's managing to slide off.

Yeah I get that, my point is that you will munt the axle or crank if the "pinch" isn't tight enough - the preload bolt might stop the arm coming off, but the splines will strip and the crank will rotate. Its a false sense of security 'upgrading' the preload bolt for retention purposes. For me having the arm fall off is only just worse than having an arm that can spin on the spindle on a hard landing.

I wonder if the pinchbolt thread or bolt is damaged or something so that you're torquing them out but the pinch isn't closing on the axle? I don't use my torque wrench on mine, I just tighten the crap out of them and they've always been fine. If they're cleaned and loctited they've never come loose in my experience and I've run Shimano cranks exclusively for about 15 years now.

 

[Gary]

Yeah I get that, my point is that you will munt the axle or crank if the "pinch" isn't tight enough - the preload bolt might stop the arm coming off, but the splines will strip and the crank will rotate.

Yeah. trust me. The bolts weren't loose enough for that to happen. ie. There's absolutely no way I'd have ever gotten the crank back onto the splines without first losening the pinchbolts by quite a bit.
An alu pre-load bolt will at least give me some warning if it starts to loosen/creak etc.. The dumb as fuck plastic one just stripped out its threads allowing the crank to eject itself.
pinch bolt and the crank threads are fine. I did check. I'm not new to this sort of shit. Just a little confused as to how it's happening in the first place.

Pinch bolts were (and are now) torqued down tight as fuck. Thinking about this though. I wonder if there's maybe a chance the plastic spacer that sits between the gap to stop you overtightening them is perhaps somehow slightly thicker than it needs to be.. I'd happily remove it on old Saints but I'd imagine there'd be a pretty good chance of stretching the crank by overtightening on these things. Hmm...

 

[gratefulbiker]

Pinch bolts were (and are now) torqued down tight as fuck. Thinking about this though. I wonder if there's maybe a chance the plastic spacer that sits between the gap to stop you overtightening them is perhaps somehow slightly thicker than it needs to be.. I'd happily remove it on old Saints but I'd imagine there'd be a pretty good chance of stretching the crank by overtightening on these things. Hmm...

Could be wrong, but I'm not sure the spacer is there to keep the cranks from being over tightened as much as it's there as a "lawyer tab" type deal. If the cranks have been tightened to the point of completely sandwiching the spacer, then they've probably been stretched and could be the cause of the problem. Ten plus years using Shimano cranks and have never needed to tighten them to that degree to keep them snug and noise free. Pretty much set and forget even without the use of a proper torque wrench.

 

[iRider]

Pinch bolts were (and are now) torqued down tight as fuck. Thinking about this though. I wonder if there's maybe a chance the plastic spacer that sits between the gap to stop you overtightening them is perhaps somehow slightly thicker than it needs to be.. I'd happily remove it on old Saints but I'd imagine there'd be a pretty good chance of stretching the crank by overtightening on these things. Hmm...

I never had problems with Shimano cranks. I, however, always remove the plastic spacer thing because it does really nothing and, like you said, it seems on some crankarms it stops proper tightening. When the cranks are new the pinch bolts lose torque after short usage although tightened to spec with a torque wrench. I guess it is a stretching of the aluminum that you see with many components. Therefore I initially bolt check them after every ride and after they have settled in you don't have to touch them ever again. If they have been overtightened you will have a hard time getting the cranks to stay tight, so always use a torque wrench.

 

[HardtailHack]

How much experience do you have with loctite 660?
is it a liquid metal filler? or an adhesive?
If used on crank splines how easily would the crank arm come off again? and how difficult is it to get the loctite off the axle spline to fit a new crank arm? (the axle splines are not damaged)

No I haven't used that one but I have used a couple of the other bearing retainer type products and they work well unless you go beyond the maximum gap. I will be using some 620 tomorrow to put a pulley back on a crankshaft as at some point the key has fallen out and the pulley has spun.
Normal red loctite may do what you want, it's usually not too hard to get off, just comes off in chips.

 

[Udi]

I'm not new to this sort of shit.

I know how to fit/torque pinch bolts

You are the self-proclaimed expert on everything here including riding and being a mechanic.

You are doing something wrong to have these problems - because I can guarantee that you are not the fastest nor heaviest rider using these cranks.

I would say that you and/or the previous owner/s have damaged the splines, and the interface will never be the same again. You can try my suggestions (I would use red, not blue loctite in your case), however the best bet is to start with a new set and follow the instructions again from that point. I would also stick with XT as a minimum standard, the lower-end cranks may use an inferior alloy and I can't speak for them.

It's okay to remove that plastic tab - if you need to tighten beyond squeezing that, then the splines are damaged anyway, so you may as well try it before replacing the set (or just non-drive crank, if set uses steel/chromo thin-walled axle ala Saint). Its actual purpose is to stop the crank falling off entirely if the pinchbolts come loose, the plastic tab has a small metal pin that goes into the axle.

My suggestions on not using carbon paste stand.
If you think that will help, you don't understand splined interfaces.

Everything toodles said is 100% correct.
Read his posts again: if you think switching the preload bolt from plastic to alloy is improving retention, there is user-error at pinchbolt installation stage and/or irreversible damage done to the spline interface.

 

[HardtailHack]

Is there any chance your crank arm is going on too far or not far enough and that may be the issue? I used to go through at least a set of cranks a year on the hardtail and my Zees are both the cheapest and longest lasting crank I have owned, I went from them to Profile Elites but they are a seriously shit design for mountain bikes so I went back to the Zees.
I have worked on a few friends' bikes with XT and even Deore cranks, I'm not a very good bike mech and I just use a bit of bearing grease on the splines and no loctite on the bolts and none of the few bikes I have worked on have had issues with the cranks loosening.

 

[Gary]

@Udi - The XTs are on a 3 yr old fleet of bikes used by hundreds. and maintained by a few. (Not all savvy). These were used as an example.

the lower-end cranks may use an inferior alloy and I can't speak for them.

My crank is an E8000. (look them up) it's 5 or 6 weeks old. I am the original owner but I didn't originally fit them to the bike.

As already stated. The alu tension bolt will give a little more security instead of stripping it's stupid plastic threads and failing! I'm not sure how you don't get this.

 

[Gary]

Is there any chance your crank arm is going on too far or not far enough and that may be the issue?.

There's a chance it was assembled with the crank not far enough on. Yes. Bike was bought complete. Bolt checked before I rode it but because of the axle being part of the motor it may well have not been on quite far enough from the factory. Causing the initial problem (crank coming off) I have wondered about this. and contacted the supplier/shop. I'm yet to hear back.

 

[Flo33]

That's what you get from the Cycling Gods for e-moped riding. You asked for it, you got it.

 

[Gary]

I know.

 

[ChrisRobin]

Doesn't Gary have an E-bike?

 

[Sandwich]

Isn't the plastic tension bolt specifically designed so that nutters can't overtighten it? Even the tool is designed so that you cannot physically go over hand tight. It's a small plastic wheel with a shitty grip on it specifically so that the bolt remains hand tight. I thought that was part of why the interface works so well. It's tensioned "just enough", then the pinch bolts hold it in place. Tension and securing are two separate, unrelated functions, unlike almost every crank on the market where they are handled by the same single bolt?

 

[Gary]

L/H E8000 cranks don't take up BB play like a normal HTII set up @Sandwich

 

[Gary]

Doesn't Gary have an E-bike?

Yes he does. but he also still has 10 other non E bikes. 2 of which are actually DH bikes.
I ask here because a lot of E bike riders seem to be either weird or scarily un-knowledgable/inexperienced.

 

[ChrisRobin]

Hahaha ok.

 

[Udi]

As already stated. The alu tension bolt will give a little more security instead of stripping it's stupid plastic threads and failing! I'm not sure how you don't get this.

If you want to gain anything from your thread asking "for input" you'll have to open your mind to the possibility that you don't already know everything there is to know on the topic.

I'd suggest you carefully re-read every post by @toodles in this thread, followed by @Sandwich's post #29, except this time with an open mind - because those are the facts - and your stubborness is stopping you from understanding them.

Any "security" added by an alloy tension bolt is a "false sense of security". There is nothing stupid about the plastic bolt, only stupid users who don't understand how the system works. As Sandwich states, the bolt AND its tool were designed specifically to stop people using the bolt for retention purposes. It is used purely to remove axial play from the system before the pinchbolts (the sole retention device) are tightened.

This is because if the pinchbolts are ever allowed to come loose enough for the crank to move across the spindle, the splines will see plastic (i.e. permanent) deformation. Of course if the alloy preload bolt is overtightened OR secured with loctite, it will be a safer failure mode, because the crank won't fall off when the pinchbolts come loose (the plastic tab is another line of defence against this, same reason why they did switch to / offer an alloy preload bolt later), but the point is: the pinchbolts should never be allowed to come loose in the first place, because if they are ridden with the bolts loose the cranks won't be the same again. The system is very clever, because small amounts of spline damage can be offset with increased torque on the pinchbolts, which is why many people who do let their cranks come loose can still use them without issue - but obviously not always the case - especially under more demanding usage.

As for the cheap cranks, they are often painted and don't have anodized spline surfaces (you'll see they are silver on the spline surface, if the cranks are black) - which means a much lower surface hardness - so when the owner runs the cranks with the pinchbolts loose, permanent damage to the splines is far more rapid and of greater magnitude. Saint and XT are both anodized at that interface IIRC, so they are a little more tolerant of poor installation, and have better chances of still working fine afterwards.

 

[toodles]

Self drilling screw through crank arm into the spindle. Solved.

 

[Gary]

@Udi Instead of fixating on one irrelivent point how about actually reading what I said?.
I understand completely what the pre-load bolt is for on Shimano HTII mtb crank and how it works. Even so as far as I'm concerned there is no fucking place for a plastic thread ANYWHERE on a high end bicycle and I will be using alloy pre-load bolts from now on. (Possibly for no other reason than to piss you off).
As already covered. The crank pinch bolts were nowhere near loose enough for the arm to rotate on the spline.
Thanks for the less condescending and as usual hugely informative part of your reply.
you'll also be happy to know I've taken your advice and removed the carbon paste from the spline.

Going from emails with CRC and the fact that the chainring lockring also came loose earlier this evening I now have a very strong suspicion as to what the real root of the problem was.


Thanks everyone else.

 

[rockofullr]

Going from emails with CRC and the fact that the chainring lockring also came loose earlier this evening I now have a very strong suspicion as to what the real root of the problem was.

Come on old chap! I didn't read to the end of this thread for a cliff hanger.

 

[Udi]

The crank pinch bolts were nowhere near loose enough for the arm to rotate on the spline.

I didn't say for the arm to rotate on the spline, I said to slide along the spline (i.e. axially). For this to happen the interface must be below correct torque, which means the moment from the rider mass on the crank can cause permanent damage to the splines. Just because you can't see rotational movement doesn't mean there isn't any, it only needs to be miniscule to cause damage.

As I explained, high-end cranks are less prone to this damage, but either way, they should never be allowed to come loose. After they've come loose once, peak interface friction may be permanently reduced. That's why I suggested red loctite for those pinchbolts on current (and more importantly, future/new) cranksets if you are having problems. Shimano grease the threads from factory hence the cleaning.

If you're on board so far, you'll now understand why it's even more critical that those bolt torques are maintained on the cheaper cranks with potentially weaker alloys and un-anodized spline interfaces. The cheapies will never be Saints, but they'll have a better chance of survival if you follow my steps, ideally from new (eg. if you score a warranty set).

I understand completely what the pre-load bolt is for on Shimano HTII mtb crank and how it works.

You think you do, but many things you've written indicate you don't.
Sandwich and toodles both posted things worth re-reading if you don't like my delivery.
The E8000 crank uses the preload bolt for even less than regular HT2 cranks (bearing preload managed internally), the problems displaying at the preload bolt are likely being created at the pinchbolts. Everything I said still applies!

and I will be using alloy pre-load bolts from now on. (Possibly for no other reason than to piss you off).

Red with rage

(circa 2009)