Hi, I have just come into this forum for the first time. I haven't found another better place too seek advice. I have got a kalkhoff Agattu SX 42 one. It is a common commuting bicycle. Its rear wheel got loose by the right bolt. I tightened it but got loose again a few minutes later from cycling. I know there is a given point where you shouldn't tighten the bolt any further with these bicycles. I got this point with the right bolt which was as tightened as the right one and didn't get loose when what I am telling you happened. Could anyone give me any advice, please?
Advice on bolts.
- Thread starter ABM
- Start date
PedalUma
Well-Known Member
- Region
- USA
- City
- Petaluma, CA
Welcome! Many bikes come with bolts that are made out of cheese. This is true of even some brands of components that are in good repute. My advice is to remove the other bolt, the good one, and take it to a hardware store where they will measure its thread count (TPI) and diameter. Buy something while you are there to be nice but not their bolts. Then take that metric information and buy high quality axle bolts using the internet. I have done this with Shimano Nexus and Alfine bolts. When I tighten these Shimano bolts well enough to hold up to the stresses of an eBike, they fail by getting stripped. Cheese. I now use high quality 'BMX' bolts on these axles. These bolts are not only much stronger, but they have a built-in washer that freely spins and has one-way locking teeth to hold against the dropouts.
indianajo
Well-Known Member
You can't use lok-tite on the threads. Lok-tite is released by heating the nut with a torch and that would burn the wire on the motor end. This is the motor shaft, right? If not a motor shaft you can use lok-tite, but then you have to carry a torch to change a flat on the road.
You can use key-tite a plumbing compound on the threads, but you live in Europe and probably can't buy it. It is $24 a can anyway. Permatex #2 gasket sealant is close but again, you probably can't get that in Europe. Clean your hands with Isoprophyl alcohol afterwards.
I double nut my motor axle, counter torqueing the two nuts to lock them. Since the motor axle is short, this involves first buying a 3rd & 4th nut. No easy feat for most hub motors, which are usually m12x1.75 instead of the usual 12x2 or 12x1.5 . Then because the first nut is so thick, I have to saw it thinner. Use a vise & a hacksaw. Then I have to grind a thin wrench to tighten the thinner nut. The result of all this work is I don't have to tighten my motor axle ever. I do have to carry two wrenches of the right size in case of a flat everywhere.
If a regular derailleur shaft on the rear, then those are usually 3/8"x26 tpi nuts. I haven't been able to buy them: suppliers send me all sorts of hex shaped garbage that they give me a refund for. That doesn't lock the bike axle. I bought a 3/8"x26 tpi tap and made some out of square keystock. Use safety glasses with power tools (drilling the pilot hole). Two nuts counter torqued solves the whole problem of the axle loosening and walking forwards in the slot under my pedal force.
You can use key-tite a plumbing compound on the threads, but you live in Europe and probably can't buy it. It is $24 a can anyway. Permatex #2 gasket sealant is close but again, you probably can't get that in Europe. Clean your hands with Isoprophyl alcohol afterwards.
I double nut my motor axle, counter torqueing the two nuts to lock them. Since the motor axle is short, this involves first buying a 3rd & 4th nut. No easy feat for most hub motors, which are usually m12x1.75 instead of the usual 12x2 or 12x1.5 . Then because the first nut is so thick, I have to saw it thinner. Use a vise & a hacksaw. Then I have to grind a thin wrench to tighten the thinner nut. The result of all this work is I don't have to tighten my motor axle ever. I do have to carry two wrenches of the right size in case of a flat everywhere.
If a regular derailleur shaft on the rear, then those are usually 3/8"x26 tpi nuts. I haven't been able to buy them: suppliers send me all sorts of hex shaped garbage that they give me a refund for. That doesn't lock the bike axle. I bought a 3/8"x26 tpi tap and made some out of square keystock. Use safety glasses with power tools (drilling the pilot hole). Two nuts counter torqued solves the whole problem of the axle loosening and walking forwards in the slot under my pedal force.
PedalUma
Well-Known Member
- Region
- USA
- City
- Petaluma, CA
With thousands of bikes it is good etiquette to open with a photo. That helps so much and it takes the burden off the reader to try to do the research. @ABM is new and could not know this, thinking that members of the forum are smarter than we actually are. Here are the nuts I have been using for Nexus and Alfine hubs. They are very strong and precise. I use a drop of oil so that the washer portion spins freely and grease the axil and nut threads.
tomjasz
Well-Known Member
- Region
- USA
- City
- Minnesnowta
Not true! Use Blue! No heat but a good hold.
Thanks for yor help. I feel obliged to tell you all how I have been dealing with my case. My usual technician is on vacation now. So I went to a new bike shop to buy a set of proper nuts this evening. they told me the nuts I had were very good so I didn´t need to buy better ones. They thoght I should bring my bicycle to their shop for inspection, so I did and when they cheked the hub they asked me to leave my bicycle there for mending. I couldn´t understand why; it just needed tightening. I pushed them and, eventualy, they explained to me that a washer was missing and the safe that prevents the wheel to drop completly was wrongly fitted. Now I prefer to say my usual and currently former technician made a still one more mistake. I hope my new technician be the right and definitive one. I had never been into internal change bycicle before I bought the one I own now. I'sorry for bothering you unnecessarily.
m@Robertson
Well-Known Member
- Region
- USA
Ordinarily I caution against using thread locker on any bolt. Its far better to use a good torque wrench and torque to spec. In fact, its best practice to *lubricate* threads in many instances, which allows a bit more torque to be applied without galling the bolt threads. When I was racing we used anti seize on the threads of wheel studs and backed off the torque spec about 10% to compensate. This kept the threaded wheel studs from getting chewed up with the repeated on/off of wheels as the day went on and the months rolled by.
BUT doing this makes it a lot easier to screw up if you don't know exactly what you are doing. The only time I think I see lubing threads commonly recommended for bicycles is on crankarm installations.
With all of that said (sorry I couldn't help but chant the mantra) probably the best form of thread locker is Vibra Tite gel. This is used by a lot of competitors in hi-power rifle competitions where very delicate screws (think scope rings) are subject to violent, repeated shocks. Vibra Tite came out of the aviation industry where harsh, steady vibration is the rule on everything. It is a gel that essentially never hardens, and doesn't actually lock down anything. But the increased resistance provided by the material is just enough to prevent anything from ever backing out.
They make super formulae that require heat, but the blue gel is easy to apply, smear on threads with a fingertip, needs no heat and continues to work even after removal/replacement.
PedalUma
Well-Known Member
- Region
- USA
- City
- Petaluma, CA
I mostly use a little grease for the reasons mentioned above by @m@Robertson. I will use red but only on things like motor mounts. On these I use upgraded bolts so they don't sheer. Using aviation grade nuts and bolts is a great idea if you want something to really hold up. Every hub-drive fat bike I have encountered has had low grade bolts that are made of soft cheese and I wouldn't assemble a wheelbarrow with them. I don't like to touch these bikes anymore because of the likelihood of me being blamed for the failure of their garbage parts. Time to go for a ride. It is 22.5C and sunny here in Coastal N. California.
I have removed bolts with red at night and you see a spark when they release.
I have removed bolts with red at night and you see a spark when they release.
Mike TowpathTraveler
Well-Known Member
john peck
Well-Known Member
An oma without a skirt guard, shocking.
tomjasz
Well-Known Member
- Region
- USA
- City
- Minnesnowta
Thanks. My blue loctite has always needs go to. However this product looks interesting. It’s here on Sunday. Thanks. Old dog, new trick!
john peck
Well-Known Member
The 3 spd + 350w bb interests me, I´ve been looking for something that suits my ´vega mixte.
The stays & fork are too narrow for hub drive, but that setup might be ideal. The ´Vega is
race built with Tange pro tubing. The frame set weighs just 3 1/2 pds. There are carbon frames
that aren´t as light. Kit specifics?
m@Robertson
Well-Known Member
- Region
- USA
sorry for not linking it earlier but it also comes in a little tube that costs a lot less. You get a lot less too but this is how I buy it most frequently. The pump bottle is a lifetime's supply I hope.
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