profile crank bolt keeps falling out

You’re probably thinking of galvanic corrosion. I don’t know if galvanic corrosion is going on since both the bolt and axle are steel. But galvanic corrosion is why you grease aluminum seatposts before putting them in a steel frame and why you anti-seize the threads of titanium bolts before putting them in your fancy new bicycle (or fancy titanium unicycle frame).

Sorry for the threadjack, but where do you even find this stuff? Is there a brand name you look for? When I asked my LBS, they muttered something about just having a big industrial-size tub, and couldn’t say how I could buy any.

Go to an auto parts store if your LBS won’t help you. There are a variety of anti-seize compounds. I think the most common is a grease imbedded with molybdenum disulphide. There are copper compounds and nickel in some of them. Loctite makes several varieties.

You know better than to give me choices :). JC, step in here…I need some ordering around.

Go to a NAPA store and get a little 4 oz jar of copper colored anti-seize. They’ll know exactly what you need. 4 oz will last you a long time. A little anti-seize goes a long ways.

Copper anti-seize is for sissies. Get uranium hexaflouride.

Thanks all for clarifying the issue. I will try out some medium strength Loctite (once my replacement bolt arrives :frowning: ), give the uni a good thrashing and report my results.

Another quick question… could I do much harm riding my Profile wheelset without the bolt in the axle?

Besides the fact that I’m letting dirt and dust in, it seems like the axle / crank interface isn’t lacking in strength (I’m not talking about doing drops here, just riding down a staircase or two)… could I do any damage? I just need to get a little trials “fix” while I’m waiting for new hardware.

Without the bolt, there’s nothing holding the crank on except the friction (or galling) between the crank splines and the hub splines. I don’t think you’re likely to damage a Profile hubset by riding it that way, but I would be surprised if it stays on for any length of time.

One thing to worry about is possible damage to the frame. With the bolt gone there is nothing holding the bearing in place. The bearing will be free to push outwards which could bend the leg of the frame, in addition to pushing the crank off the axle.

If you’re really anxious to ride you might be able to get a standard bolt and washer at a local fastener shop. A fastener shop is a fancy word for a shop that specializes in screws and bolts. Check the phone book. Bring in the flush mount bolt so they can find a bolt with the same threading and the same length and a washer with the right OD.

Here is a picture of the standard bolt (non-flush mount) that Profile uses. It will stick out and could hit your ankle, but you’d be able to ride.

ProfileBolt.jpg

Thanks for the info, great knower-of-all-things!

The picture, however, taunts me in its pixellated brilliance.

Every time I try to reach out and grab the bolt my fingers whack the monitor… so close… yet so far… must… get… bolt! :angry:

Don’t ride it without the bolt. Not only can you damage the splines, you will. It won’t be catastrophic, but the splines wear enough as it is, take the bolt away and you will greatly increase the wear on the equpiment. To give you and idea of what the bolt does, on my trials uni with the SH hub, the cranks move about 0.010-0.020" as measured near the pedal threads, when there’s no bolt. With the bolts fully tightened, the cranks don’t move at all. I would say the friction of the interface adds measurable strength to the system.

All splines will wear, even those in a semi-permanent interface like our uni hub/cranksets. My muni hub/crankset was amazingly tight when i got it, now it’s super loose, even though I keep the bolts as tight as possible. It’s best to avoid as much wear as possible.