Dear WETH, The NDS crank is toast given how much time you've spent mashing on it loose. If It won't stay tight, it is trash/recycling. The bb is fine--hardened steel doesn't tend to deform much when it is mated poorly with aluminum.
Next time, grease the tapers, crank it TIGHT (that's 40 n-m, or as tight as you can make it with a peanut-butter wrench) and snug the crank bolts back to torque (a torque wrench is helpful, but hellatight with a 9" wrench is about right) after your first weekend riding. Carry a suitable wrench (either an 8mm hex key, or a 14 or 15mm PB wrench depending on your bolts) until you're confident the NDS has settled in. Resist the urge to keep snugging up the bolt--you can split the 2deg taper.... Best, Will William M. deRosset Fort Collins, CO On Wednesday, May 6, 2015 at 5:26:25 PM UTC-6, WETH wrote: > > Short Version: My non driveside crank arm won't stay tightened after I > took it off to clean and inspect. Any ideas why? > Long version: really it is too long: > Four miles into my eight mile commute at 6:30 on Monday morning last week, > I felt a wobble as I pedaled. The left crank arm had worked loose and was > almost off the bottom bracket spindle. Fortunately the crank bolt had not > fallen out. Taking out my tool bag I discovered I had no hex wrench large > enough to fit the bolt. I pushed the arm on as far as I could, hand > tightened the bolt, and used a needle nose pliers to tighten the bolt a bit > more. A mile later, the crank arm worked loose again. I repeated by > previous repair. This happened twice more before I was able to make it to > work. Worst case scenario would have found me walking up hills and > coasting down them, which would have been fine. I wasn't late and it > wasn't cold or rainy. Once at work, the fine folks in my facilities office > had the appropriately sized hex wrench. I tightened the bolt and enjoyed a > trouble free ride home. > > Four commutes later, or about 64 miles, the same crank arm loosened again. > This time I had the tool and tightened it. > > About 100 miles before the arm came loose the first time, I had taken off > both crank arms to clean and inspect. > > Now I am nervous. Have I stripped the bottom bracket spindle/bolt > interface? Have I over greased the BB spindle and crank arm? ( I have had > no trouble on the driveside) Thoughts? (I have ordered a new crankset/BB as > this combo has 10,000+/- miles trouble free till now) (crankset is a > Nashbar mountain triple (ISIS) on a Nashbar BB (ISIS)) > > Several other questions for the "MacGyvers" and engineers to satisfy my > curiosity: > 1) Any other ideas for tightening a loose crank bolt without a hex wrench? > > 2) With a loose crank arm, is it better to pedal in a high gear and mash > fewer strokes for power, or spin in a lower gear with less force, or does > it matter in regard to how quickly the arm will work loose? > > Thanks, > Erl, who now has a hex wrench that fits his crank bolts in his tool bag, > Houston > PS: on my commute this morning, on a different bike, I broke the chain. I > did have the right tools. Feeling like I have momentarily fallen out of > favor with the cycling gods. > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
