Benja Posted January 9, 2018 Posted January 9, 2018 Hi, The bolt connecting my left crank arm to the bottom bracket keeps loosening by itself. The first time it happened I was out on Bottelary Hills track without tools and it caused damaged to the crank arm and bottom bracket thread. I had it replaced, however now it is loosening again.Does anybody have an idea what can cause this? I am a large guy (1.95m 140kg), maybe it could be some riding style.? Benja Sent from my WAS-LX2 using Tapatalk
BaGearA Posted January 9, 2018 Posted January 9, 2018 Square taper crank Or arm coming off the spindle of A two piece/ three piece crank? Blue locktite + proper torq usually solves this issue
Dicky DQ Posted January 10, 2018 Posted January 10, 2018 Is it Truvative or SRAM? If so it is due to a poor design for big fellows. The non drive side is pulled against the BB bearing if there is any wear on the bearing it allows the crank arm to work loose. It is not an issue for the lightweights but for the bigger rider it is an issue. Well for me it was x 3. Changed to Shimano and never had an issue again.
madbradd Posted January 10, 2018 Posted January 10, 2018 Is it Truvative or SRAM? If so it is due to a poor design for big fellows. The non drive side is pulled against the BB bearing if there is any wear on the bearing it allows the crank arm to work loose. It is not an issue for the lightweights but for the bigger rider it is an issue. Well for me it was x 3. Changed to Shimano and never had an issue again.Drop of blue loctite sorts this out too.
Grease_Monkey Posted January 10, 2018 Posted January 10, 2018 Another +1 for blue Loctite and proper torque. I have gotten my bike from many a service with the crank arm bolt not tightened to more than 7 or 8NM of torque (resulting in exactly the same issue you are experiencing) when that specific bolt requires more than 40NM of torque to be tightened properly. Splash some of the blue Loctite onto it, and don't be shy with tightening it properly using an allan wrench with lots of leverage!
Benja Posted January 10, 2018 Author Posted January 10, 2018 Thanks guys! I'll get some lock title on there and tighten it properly! Hopefully no more pushing for me [emoji3] Sent from my WAS-LX2 using Tapatalk
droo Posted January 10, 2018 Posted January 10, 2018 So many solutions offered without knowing what kind of crank it is... So - what kind of crank is it?
sirmoun10goat Posted January 10, 2018 Posted January 10, 2018 I had the same issue with a Raceface Turbine. Initially had an issue with a creaky pressfit BB in my stumpie hardtail, so changed the PF BBto a Wheels MFG BB. This worked for a while but the crank kept working lose. Changed over to SRAM GX crank the other day, with the Wheels MFG BB - so far, no issues.
Eldron Posted January 10, 2018 Posted January 10, 2018 So many solutions offered without knowing what kind of crank it is... So - what kind of crank is it? To be fair he said "bolt" not "bolts" so it rules out new Shimano cranks and that leaves a design where the crank bolts onto the shaft with one big bolt. A little Loctite (or some ordinary paint in my opinion) is always the solution to his design!
Jewbacca Posted January 10, 2018 Posted January 10, 2018 If it's square taper, then yes. If it's SRAM, Lyne, Aerozine or an older Race face single bolt crank set there could be a few issues which a blop of blue lock tite doesn't fix, but can mask, doing damage to the BB/Spindle in the long run. As with all of these, show me the pitchaaas!
Eldron Posted January 10, 2018 Posted January 10, 2018 If it's square taper, then yes. If it's SRAM, Lyne, Aerozine or an older Race face single bolt crank set there could be a few issues which a blop of blue lock tite doesn't fix, but can mask, doing damage to the BB/Spindle in the long run. As with all of these, show me the pitchaaas!I'm intrigued and curious. How can stopping a bolt coming loose mask long term damage?
droo Posted January 10, 2018 Posted January 10, 2018 If everything's working as it should and torqued to spec, you shouldn't need Loctite to keep it from coming loose. Bolts coming loose are usually a sign of not being torqued properly, incorrect assembly or wear on the spline or taper. Loctite can temporarily eliminate the symptom without addressing the cause.
Eldron Posted January 10, 2018 Posted January 10, 2018 If everything's working as it should and torqued to spec, you shouldn't need Loctite to keep it from coming loose. Bolts coming loose are usually a sign of not being torqued properly, incorrect assembly or wear on the spline or taper. Loctite can temporarily eliminate the symptom without addressing the cause. But... I do agree with you though - try loctite once and if it comes loose again there is another problem. Blind holes are always an issue as their is no fixture on the other end of the bolt - especially in systems where there you have a long lever like a crank moving perpendicular to the thread.http://images.jbi.bike/1200/22414.jpg
Kalahari Vegmot Posted January 10, 2018 Posted January 10, 2018 Slight hijack...... I've been thinking of getting one of these so I can use a "normal"(Shimano) bb on my GXP crankset. Is this a good idea? I'm scared that Shimano bb's won't be able to cope with the side stress of the GXP's design. Hijack of...
usxorf Posted January 10, 2018 Posted January 10, 2018 Slight hijack...... I've been thinking of getting one of these so I can use a "normal"(Shimano) bb on my GXP crankset. Is this a good idea? I'm scared that Shimano bb's won't be able to cope with the side stress of the GXP's design. Hijack of...What's wrong with gxp BB (apart from how expensive they are)?
Kalahari Vegmot Posted January 10, 2018 Posted January 10, 2018 What's wrong with gxp BB (apart from how expensive they are)?How expensive they are.
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