"Akio Ohtori - RIP Oppo" (akioohtori)
07/20/2018 at 10:51 • Filed to: tooty scooty
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"Akio Ohtori - RIP Oppo" (akioohtori)
07/20/2018 at 10:51 • Filed to: tooty scooty | 3
| 3 |
On last check-in, my motorized 2-stroke bicycle project broke down after 3 short miles, thanks the the rear sprocket slipping and causing the chain to bind. It gets weirder from there...
Disclaimers: This build is for entertainment and learning purposes only. I do not expect to get any practical use out of the end product. I understand this is the worst choice of 2-wheel motorized transport.
At first, the problem seemed p retty simple. The rear sprocket had skewed and was causing the rear sprocket to be misaligned with the chain guide every half rev. This caused the chain to ride up on the sprocket, dramatically increase tension, and casing the whole thing to bind.
Simple enough, just selectivly tighten the nine bolts connecting the sprocket to the spokes to correct the skew. Right?
Wrong.
First off, the sprocket bolts are an absolute pain to access when they’re on the bike. After struggling with that longer than I’d care to admit, I got the skew where the chain wasn’t binding.
This led to the discovery of problem B: the sprocket was no longer centered.
Crap. So after spending even more time struggling to loosen the bolts I had just tightened, I grabbed some scrap wood and attempted to realign the sprocket using a dead-blow.
It wouldn’t budge.
Resigned to my fate, I finally decided to remove the rear wheel, which, in hindsight, I should have done in the first place.
The de-centering was more worrying. Even more so was how tight the bolts were, how easy we were taking it on the engine, and how few miles it took for it to all go so wrong.
Clearly some googling was in order.
With very little googling, I discovered there is a solution to this problem. Pay money more money than you are strictly comfortable with to change the sprocket mounting from the spokes to the hub.
On the surface, this is an excellent idea. The hub is the center of the wheel and therefore is... centered. Further, you’re no longer putting clamping stress or rotational stress on your spokes, which means you’re not going to destroy them as quickly.
The only downside I could see is the thing costs $70.
Goodbye budget! I hardly knew ye.
The new part
The part seemed pretty well made and install was simple. The only thing that had me worried is the screws didn’t have much resistance screwing in. To allay any fears of those backing out, our good friend blue loctite was employed.
Overall I’m happy with the upgrade. The downside is it does introduce another adjustment as the hub clamp can be moved in and out, but this also solves my problem of the chain periodically rubbing on the frame.
Test drive presented no problems outside of the need for further adjustment, so overall I am pleased. Not terribly happy I felt the need to replace a major component so early in the process, but here we are.
M.T. Blake
> Akio Ohtori - RIP Oppo
07/20/2018 at 10:57 |
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After I saw your first post I got curious and started searching. Not only is it easy to find the gas kit but I saw an electric kit and it got me thinking:
HYBRID DUAL MOTOR SCOOTY!!!!!!!!
Best idea evvvvvvvar. Do it.
Nom De Plume
> Akio Ohtori - RIP Oppo
07/20/2018 at 11:15 |
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I’m not going to revisit how low my expectations were for this kit, but holy shit is that a fucking deathtrap mounting the sprocket to a couple spokes. I mean there is no way in this physical world a thin piece of metal whose mechanical destiny is flexing to keep the wheel true should even be a consideration short of tolerance between it and the chain.
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Akio Ohtori - RIP Oppo
> Nom De Plume
07/20/2018 at 11:30 |
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Haha you are not wrong, though it isn’t that bad. The standard kit design uses 9 bolts and two pieces of old tires (I wish I was joking, but hey recycling I guess) to clamp the rear sprocket to the spokes. I was never in love with this, so it failing after just 3 miles helped justify its replacement. (The picture below shows it in the process of assembly, there are three of the metal plates total.
The new system clamps to the hub and should be better in every way.
