Saint crank problem

[kim]

I was riding today and my not drive side crank fell off. The cap that is used for tensioning was missing. The pinch bolts were still tight I had torqued them to specs with a torque wrench. I put the arm back on and tightened the pinch bolts very tight and the arm slipped off again. Has anyone else had this problem?I am surprised the pinch bolts wont hold the crank on.

[blunt boy]

You need that cap. Seen it happen before without it. Make sure you torque the new cap to spec before tightening the pinch bolts.

[zahgurim]

Previosly the Saints came with a plastic tensioner cap. It = poo.

You can buy an alloy cap to replace yours, and it's solid forever-and-ever after. Should cost you about $10-12. All the new Saints now come with the alloy cap.

I also recomend replacing the pinchbolts with longer ones, as the stock bolts are pretty short. Longer ones will let you torque down.

[kim]

Thanks it was scary it fell off i was lucky it happened while pedaling down the road

[Jeff M]

Did the splines get damaged when it slipped off the first time?

[DaveM]

The tensioner cap only gets tighten "snug" anyways, the plastic one is good enough. It's just there to slide the cranks onto the splines, it serves no purpose to keep you cranks on, in fact you can remove it once your cranks are installed.

Have a look in the little gap in the crank arm where the pinch bolts are. When they assemble the cranks at the factory they put a little plastic spacer in there to keep the cranks from getting tightened too much (at least that's why I think it's there.) You have to take it out when you put them on your bike.

Same thing happened to both my Saints and Hones.

[blunt boy]

The tensioner cap only gets tighten "snug" anyways, the plastic one is good enough. It's just there to slide the cranks onto the splines, it serves no purpose to keep you cranks on, in fact you can remove it once your cranks are installed.

I used to think that too until I tried it on a friends bike and the arm didn't stay on for even one ride. I think the cap keeps the arm from "working" loose as well as providing the initial snug.



Have a look in the little gap in the crank arm where the pinch bolts are. When they assemble the cranks at the factory they put a little plastic spacer in there to keep the cranks from getting tightened too much (at least that's why I think it's there.) You have to take it out when you put them on your bike.


This could def be the prob as well.

[TheGiggler]

you NEED that plastic/alloy nut. the pinch bolts will NOT normally hold the cranks on.

my plastic nut broke and even though the pinch bolts were tight the non-drive crank started to work itself off the spline. no damage to the splines or anything.

if they now make an alloy cap i would def. go with that. the plastic ones do break now and then, and when they do you have a good chance of losing the non-drive crank.

also, the pinch bolts that come stock on Saints are really short. Lou @ Obsession replaces them with longer bolts so that you can safely put a little more torque on them.

[Oldfart]

you NEED that plastic/alloy nut. the pinch bolts will NOT normally hold the cranks on.

my plastic nut broke and even though the pinch bolts were tight the non-drive crank started to work itself off the spline. no damage to the splines or anything.



Is it possible that the broken preload bolt is a symptom of the crank arm coming loose and breaking bolt off? The preload bolt does not need to be torqued down supertight. I think the torque is around 7 inch pounds but I could be wrong. It is low whatever it is.

How tight were your pinch bolts and did you check them now and again? If memory serves correctly the torque spec is around 100 inch pounds minimum to 130 ip? It is possible to overtighten to the point where the gap is closed completely and the crank pinch is stretched too far and can never be tight enough. Was the torque the same on the two pinch bolts? Did one get tightened too much deforming the crank such that even at the correct torque the other bolt could not make the clamp even? The proper way to tighten those pinch bolts is one then the other in little bits until proper torque is acheived. If you do up one as tight as possible then do the other, that would probably end up with an unven clamp force which would lead to the crank wiggling off and blowing the plastic cap bolt in the process.

That preload cap serves a similar function to the top cap on the stem. It's there to add preload to the headset, but once the stem is correctly torqued, you could remove it and in theory, the headset adjustment won't change. In practice some guys ride so hard or the headset/headtube is not quite square enough and the top cap adds a little bit of assistance to keeping things right. But not much.

[blunt boy]

Was the torque the same on the two pinch bolts? Did one get tightened too much deforming the crank such that even at the correct torque the other bolt could not make the clamp even? The proper way to tighten those pinch bolts is one then the other in little bits until proper torque is acheived. If you do up one as tight as possible then do the other, that would probably end up with an unven clamp force which would lead to the crank wiggling off and blowing the plastic cap bolt in the process. .


This is definately key.


That preload cap serves a similar function to the top cap on the stem. It's there to add preload to the headset, but once the stem is correctly torqued, you could remove it and in theory, the headset adjustment won't change. In practice some guys ride so hard or the headset/headtube is not quite square enough and the top cap adds a little bit of assistance to keeping things right. But not much.


I believe it comes into play a bit more than a headset cap. The amount of side load on the crank arm cap is probably way more than the upload(?) on the top cap.

[the Master Plan Dan]

I was riding today and my not drive side crank fell off. The cap that is used for tensioning was missing. The pinch bolts were still tight I had torqued them to specs with a torque wrench. I put the arm back on and tightened the pinch bolts very tight and the arm slipped off again. Has anyone else had this problem?I am surprised the pinch bolts wont hold the crank on.


See above for an answer but the exact same thing happened to me... but I was jumping of Staff Housing in the Bone yard... pretty scary when your crank comes off then.

Fixed according to above and have never had a problem since!

[TheGiggler]

Oldfart, thanks for the reply, but the cranks were actually installed according to spec and I'm not the only person to every have this happen to them.

fact is, you need that preload cap on the cranks at all times, and should you ever lose it or break it, get another one ASAP. the pinch bolts, even at Shimano's torque spec are NOT sufficient to hold the crankarm on for multiple shuttles of cypress.

[*Pepe*]

i'd have to agree with Oldfart on this one which is to say the cap is intended to adjust the side load of the crank and the pinch bolts hold it in place.

i disagree that shimano's torque specs are insufficient. i've been using mine for years without any issues.

in order to avoid accidentally crushing the cap, after lightly tightening the pinch bolts i've loosened the cap a few degrees so it doesn't get crushed under full torque specs. i've never lost or broken a cap, nor have i lost a crank arm in all my time riding the crank. anyway, just my experience...

[TheGiggler]

you guys know it all. i suggest you all remove that cap, go shuttle the piss out of cyps and let me know how many runs until your non-drive crank is slipping.

thanks.

[the Master Plan Dan]

The cap is needed....

I got the Alloy one from Fanatikco in Whistler...

XTR was Alloy and the rest were plastic.

[Oldfart]

you guys know it all. i suggest you all remove that cap, go shuttle the piss out of cyps and let me know how many runs until your non-drive crank is slipping.

thanks.

Actualy I tried once. You can't remove it with the pinch bolts done up tight. It may help more than a headset top cap because the pinch bolts do hold it in place.

The problem though is probably not related to the preload bolt but pinch bolts coming loose in hard riding. It's no different than checking old school square tappered bb bolts or ISIS bolts or Octalink bolts periodically. Or any crank fixing bolts for that matter. Or stem bolts, axle nuts etc. etc. The harder you ride, the more often you need to check bolts. And frames for cracks while your at it.

When I ran Saint cranks I think one time they were a little loose when I checked them. Once an issue on my XTR cranks too. Just a little play noticed though and it never came off.

[*Pepe*]

you guys know it all. i suggest you all remove that cap, go shuttle the piss out of cyps and let me know how many runs until your non-drive crank is slipping.

thanks.

hey man, it's just a different opinion based on my experience, which for what it's worth, is perhaps a bit more than most on this board when it comes to this topic in particular.

also, IMO it may pay dividends to know a bit about your fellow board-counterparts and the experience they just might bring to the table before you call them "know it alls".

'nuff said.

[kim]

Did the splines get damaged when it slipped off the first time?
No the splines seem fine i got a new cap from Cove today and re torqued everything with lock tight. I am going to retorque the bolts every few weeks. I am thinking the picnh bolts loosened over time letting the cap fall off , the factory bolts are very short with very little thread engagement. I replaced the pinch bolts with longer ones and torqued them to 135 in pds

[thewwkayaker]

Hmmm - it would seem to my limited knowledge that a plastic (original spec) "bolt" is not intended to hold cranks on and if the pinch bolts came loose it's not likley to hold them on for too long. Perhaps Shimano has seen the error of their ways and this is the reason for the newer alum cap? I noticed that you can't (and shouldn't) put too much torque on the plastic/alum cap (nor is the "tool" they sell for it equipt to allow for much torque at all). Without the pinch bolts the cranks would come off pretty quick I'd imagine. I have found the pinch bolts coming loose at times - perhaps using the longer bolts would help. What about some blue locktite??

I can see that perhaps when the pinch bolts are applied the cap is unlikely to come loose easily and thus as long as the pinch bolts are doing their job it would be even harder for the cranks to come loose.

Then again I understand they've redesigned them for 2008?

[blunt boy]

hey man, it's just a different opinion based on my experience, which for what it's worth, is perhaps a bit more than most on this board when it comes to this topic in particular.

also, IMO it may pay dividends to know a bit about your fellow board-counterparts and the experience they just might bring to the table before you call them "know it alls".

'nuff said.

So you've ridden without the cap? Hard?

[*Pepe*]

I am going to retorque the bolts every few weeks.

just some friendly advice to consider backing off the bolts every time before re-torquing.

what i am trying to say is if you tighten, and check them again by tightening them, and check them another time by giving them another nudge, you could ostensibly end up over-tightening over time. this goes for pretty much most bolts on a bike, IMO.

[*Pepe*]

So you've ridden without the cap? Hard?

only on my DJ bike but i wouldn't consider riding DJ's "hard".

however, when i install the cranks on my other bikes, after i set the side load with the cap, i lightly set the pinch bolts, then back off the cap a bit before tightening the pinch bolts again.

the cap does offer some lateral resistance, but it's certainly minor like Oldfart suggests.

[ESHER SHORE]

when Hollowtech II was first introduced an alloy cap was made by one of the small component manufacturers here in UK, and lots of people that "upgraded" to the alloy cap ended up overtightening their preload adjustment and damaging the Hollowtech II bearings

You don't need alot of torque to pre-load the Hollowtech II system, once tightened the load is taken by the twin pinch bolts.

Getting the bottom bracket cups faced, the spacing correct on the external bearings and correct assembley will see your Hollowtech II setup last a long, long time...

the plastic cap is plastic for a reason...

...as the Shimano TL-FC16 (nylon) tool is designed to slip at the correct torque to stop you ovetightening it too.

the hollowtech II pre-load cap end of the BBT-9 Park tool is also designed to slip at the correct torque to stop overtightening

the small plastic plate with the steel pin that came on later Hollowtech II cranks is actually a locking plate, which is pushed down whilst tightening the twin pinch bolts, and the steel pin at the bottom of that plate located into a hole on the Hollowtech II axle.

all the Saints or XT hollowtech IIs we get from Shimano Distrib. "Madison" are still coming with the plastic cap

XTR has a completely different system to Saint or XT and XTR comes with 3 specific tools (1 is nylon,2 are metal) to preload and tighten the crank arm.

[Oldfart]

No the splines seem fine i got a new cap from Cove today and re torqued everything with lock tight. I am going to retorque the bolts every few weeks. I am thinking the picnh bolts loosened over time letting the cap fall off , the factory bolts are very short with very little thread engagement. I replaced the pinch bolts with longer ones and torqued them to 135 in pds


That's the ticket. And in case you didn't know, you should back off bolts to retoque them as pepe says. A few years ago when superlight stems hit the pro road circuit, the pro mechanics ended up stripping a bunch. The typically used small diameter titanium bolts threaded into aluminum or magnesium stems. Few pro mechs had or used torque wrenches but they all checked bolts for tension. Their method was to check all bolts by simply applying a little tightening pressure with a wrench and often it resulted in a little turn of the bolt. Over time those bolts were checked this way so often that they got stripped. Stem suppliers then told the mechs to get and use torque wrenches properly. I read this on velonews or something like that and went out and bought a torque wrench to use on my light parts. Torque measurements and settings are usually for lubricated bolts too. The only dry torque setting on a bike that I know of is the Campy Record seat post.

[Oldfart]

you NEED that plastic/alloy nut. the pinch bolts will NOT normally hold the cranks on.

my plastic nut broke and even though the pinch bolts were tight the non-drive crank started to work itself off the spline. no damage to the splines or anything.

if they now make an alloy cap i would def. go with that. the plastic ones do break now and then, and when they do you have a good chance of losing the non-drive crank.

also, the pinch bolts that come stock on Saints are really short. Lou @ Obsession replaces them with longer bolts so that you can safely put a little more torque on them.


What might be happening is that the plastic bolt deforms when the pinch bolts are done up tightly and that allows the splined end of the spindle to squish and that allows the crank arm to "walk" off the spindle. An aluminum nut is stiffer and maybe allows less or no deformation of the spindle?

[biggles604]

Is it just me, or does this just seem like a design flaw? Why would they put a reliance on an end cap, when the pinch bolts should be able to do the job?

[blunt boy]

I've never had a problem with mine. Only tighten them when after I remove the crank to service the chainring. NOTHING has come loose on mine.

Tried to run a friends without the cap. We used my cap to snug the arm in, tightened the pinch bolts to spec and the arm fell off 1.5 hrs into the first ride. While this friend is a big guy he never even left the ground.

kim, I hope there has been some useful info in here for you and that your crank probs are gone. They are great cranks when set up properly.

[Dan0]

Well you could do what Thomas did and put a headset cap in there with a starnut :P

http://www.declinemagazine.com/Nucleus/media/4/20070507-IMG_0827.jpg

[kim]

I hope everyone running saint cranks checks them on a regular basis a crank falling off could be devastating

[Jerry-Rig]

Vanderhams cranks.....

http://www.declinemagazine.com/Nucleus/media/4/20070507-IMG_0827.jpg

[ESHER SHORE]

something i have noticed with all the custom build's we've done using Hollowtech II cranks, when the bikes come in for first free service (after approx. a month) the cranks have usually slacked off a little with use

when i loosen the pinch bolts i can normally increase tension with a small turn on the pre-load adjuster indicating to me that the cranks have loosened / settled a little

found using a touch blue loctite on the pinch bolts and getting the pre-load "snug" allows you to leave the cranks alone for months with no work ;)


have seen a couple of people overtighten the pinch bolts using grease and too much torque, and stretch the clamps to give a loose fit on the axle splines...luckily can get non-driveside arm as replacement part