Turtle Speed

Getting some apparent oddities with the wheel-truing process on a kid's bike. It has 18" wheels, really inexpensive department-store stuff. The rim braking surfaces flare outwards, like \_/, and aren't parallel like most wheels, |_|. The spoke pattern seems normal to me. I have successfully trued other wheels before in hobbyist-style, flipping the bikes over and using brake pads as a guide. I don't have a truing stand yet.

The main issue is, it seems like tightening or loosening one spoke causes major changes elsewhere. I know that adjusting spoke tightness can cause minor reshaping of the rim outside the immediate area, but this is beyond what I'm used to. I feel like a cat chasing its tail, trying to get one part straight and suddenly another part looks bent!

The weird thing is that while I was eventually able to get the left side of the \_/ rim in not-too-terrible condition, the right side still looks a lot more wobbly! Is that normal for this rim shape? Am I just going crazy? Any particular tips or things to keep in mind?

xenologer

You can't polish a turd.


Just make it work well enough to last the 2months before next growth spurt and it gets thrown away.

JTGraphics

The only time I see this is when spoke tension is way off, I have never had trouble truing cheep kids bike wheels for the grandkids. You may want to loosen them all and start over so you know what's going on with the tension as long as the rim isn't physically bent.

blown240

Generally kids wheels have a lot less spokes than a 26" or a 700c. And the rims are definatly not held to as strict of standards. So its alot harder to perfectly dial in a wheel. As mentioned above, tension is a big issue. Is the wheel is round and just not straight, You may need to take the tire off and "adjust" the rim itself with a couple well places "taps" of a hammer... If its not round and seems like the hub isnt centered in the rim, then the tension may be off.

Hope this helps.

speedy25

Unfortunately xenologer has it right. The cheaper a bike is the more headaches it causes to try and make it right. DO the best you can and leave it at that. Cheap parts make it almost impossible to do a job well.

-SP

jolly_ross

If the left side runs true (ish) and the right is still wobbly to a greater extent - then the rim cross section must be inconsistent. If this is the case then it will be very very hard to get both sides running within the same tolerance. Like xenologer says - make it work "well enough". The kid isn't looking for a TdF win on it - probably just wants it to roll down the driveway and do a passable skid at the bottom.

bradtx

Turtle Speed, I recently went through my 3 YO grandson's Christmas coaster brake bike. All I could really do was make the bike somewhat better for any possible training wheel bike races at the park. Don't become too OCD about it, bikes at this level are good for their intent, but a bit crude.

Brad

reptilezs

if the wheel spins in the frame without obvious wobble leave it alone. just make sure the bike is safe. cones adjusted and bb. coaster brake. stem/bars tight. hand brakes are hit and miss usually you need to replace the housing. if it has a coaster brake you can take the hand brakes off

Turtle Speed

Alright, thanks for the tips, everyone. Maybe I was just obsessing too much and expecting too much. I'll keep at it but try to relax my standards a little.

Now I need to start studying the mechanics of coaster brakes ASAP. I like to service everything when I work on a bike. Otherwise it feels like going to bed without brushing your teeth.

Will probably be back with more dumb questions in the future...

mrrabbit 

With these small cheap almost "v" rims, just get it good enough as suggested by xenologer...the kid will be too busy babbling with his buddies about the next insane stunt to even pay attention...

=8-)

Turtle Speed

Bump!

I see some weird stuff with the way the cabling is set up on cheap kids' bikes. Since the hand brakes are usually in poor working condition (never felt so many crunchy levers in my life), and I'm about to start fixing some up, I wondered if maybe there was a better way to route the cables.

For the bikes with one hand brake, this is how a lot of them are set up:



Would it be possible, and a good idea, to put the lever on the right side? Couldn't I remove the grips, take the lever unit off the left side, flip it around, put it on the right side, put the grips back on, and then redo the cabling with a straighter approach to the brake, like this?



If it's possible, the only downsides I can think of is it's technically inverted, so that the 4mm hex screw which adjusts lever position and angle would then be on the underside. I don't see that as a big deal, plus I doubt anyone has the tools or inclination to change it anyway. Or it might get the kid used to the right handbrake affecting the front wheel, so that way down the road when they ride a "normal" bike and the left brake affects the front, suddenly it's the reverse of what they're used to. But isn't that worth it for the straighter cable approach?


.........


Here are how a lot of the 2-handbrake setups are cabled:



Again I had a similar idea of redoing the cabling. I could run the right side to the front and the left side to the back, something like this. The idea would be to eliminate that weird question-mark-shaped route which is currently going to the front wheel, and hopefully the route to the back wouldn't be any worse off.



Good idea? Bad idea?
I'm redoing the housing anyway, so it wouldn't really be much more work.

jsharr

Left is front, right is rear is pretty standard. I would keep it that way. I would run the front cable in front of the steerer tube though.

Kimmo 

That was my first thought, but a wheel is a wheel and the most important component is its build, so when the OP described chasing his tail I realised because they're tiny wheels they're low spoke count, and remembered a 16h wheel (well actually a 32h rim on a 16h hub) I built recently.

I was having a similar experience with that wheel for a while before I stopped and had a think about it, and I figured somehow the inverse relationship between a spoke's influence and the number of them is nonlinear.

In other words, a spoke in a 16h wheel has more than twice the job of a spoke in a 32h wheel. Don't ask me how, this is just intuition and a bit of experience talking. Even if it's thoroughly incorrect, that understanding helped me to finish the wheel.

Tiny tweaks make big differences; tread lightly when you get close.

Turtle Speed

Bump again!

Can anyone give me some insight about what's going on with the fastening devices on the rear wheels of many kids' bikes?

Some of them are simple and just have a 15mm axle nut.

Others have a 3-piece setup, and those are the ones that confuse me:
- 15mm axle nut on the outside
- Some sort of "plate" just inside
- 17mm nut further inside of the plate

It looks like this:



What's the purpose of the plate piece? It's not acting as some sort of washer, is it? I've seen kids' bikes where it looked like the plate fit over the training wheels some way... but what exactly is the plate doing?

Also, why 3 pieces instead of just a single axle nut? In those cases, is it really the 17 that's securing the wheel in place? And that way you can add/remove training wheels by popping off the 15 on the outside without worrying about screwing up the alignment of the wheel?

I want to understand everything about how they are set up, all the moreso because occasionally a bike will be missing one of the above-mentioned parts (like have a plate on one side but not the other).

Andrew R Stewart 

Photo shows the brackets used with training wheels. Thin (usually 17mm) inside nuts hold the wheel in the drops. Brackets have a tab engaging the slot to keep them from spinning. Training wheel arm would (if they were present) have a channel cross section, fitting over the brackets. Outside nuts (usually 15mm) hold the training wheel arms tight against the brackets.

If training wheels are removed I like to use the standard 15mm nuts to hold the axle in the drops and return to the customer the rest, zip tied to the training wheels for future use. Andy.

metalpossum

I did a full restoration on a kids bike, I'd never suggest it in my entire life unless the kid was worth the swag value of something vintage like the one I did.
This one was for my eldest niece.

When it comes to "working" on them, if it's single speed/coaster brake, keeping good chain tension and the coaster brake strap secure is a good starting point for safety.
It's really no different to working on most department store bikes, they're all made in the same inferior manner. Just learn about quill stems, threaded headsets and non-sealed bottom brackets and you'll be good to go.

Turtle Speed

Thanks everybody!

I'm having a blast working on these bikes, and the kids love them too.

bikeman715

The problem in your photos is the cables are way to long for the bikes . Raise the handlebar (stem) to it max , leave enough cable so the can turn in both direction , cut to size then the lower the handlebar to where they need to be.

Turtle Speed

Bump again. Any reason I can't join together sections of multiple chains to 1 new chain?

Sometimes I replace a rusty old chain with a new one. Because kids' bikes are so small, I get a lot of extra links left over from when I break the new chain. Couldn't I save up 3 or 4 sets of these extra leftover links and join them all together into one fresh new chain? I would make sure they're all of the same make and model of chain, and they would all be brand new to avoid mixing chains of different wear amounts.