Need a nut for my Vivi 20 inch bike

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BWolcott

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I've lost a nut holding the front wheel to the frame. I took the other nut off and brought it to a fancy hardware store for a simple replacement. However, they could not determine its size, whether standard or metric. Model of the bike is MT20UL. Any ideas for what should have been a simple fix?
 
I did a quick look at Vivi's website and did not see a specific nut for wheels called out. They have a nice website with a community page and online support. You could probably get the info you need there. Sometimes I'll buy a couple different sizes at the hardware store to see what will work. Not the most efficient method but it usually works. You'll want to pay attention to the threads. They may not be the standard coarse thread type.
 
It bothers me that they couldn't tell you if it was sae or metric. Did they have calipers to measure it with, or a thread gauge. I just skimmed through an assembly video for a Vivi bike and the fellow was using a 15mm wrench to put on the front wheel. That would most likely be a 10mmx1.5. which would be standard for a lot of bikes, unless you were using a thru axle. At some point you should pick up a cheap, digital caliper. They are very useful and you could measure the diameter of the bolt and check the likely size with Google. For now, I would take in your wheel and start with that nut.
Screenshot_20250309-105047_Chrome.jpg
 
I know nothing about your bike but mine is an M12 X 1.25 which is the finest of the common M12 tread pitches. Hardware store pitch gauges may not have all of the metric thread pitches which may be why the hardware store was lost. I'm almost sure the thread is metric in your case. Since your bike does not have a front motor, I would expect your axle to be smaller, probably an M10 X 1.0 or M10 X 1.25. Could also be a M10 X 1.5 but I doubt it since course threads are not generally seen on axles.
 

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You are right. It could be a different pitch. Bolt Depot has a pdf. chart for the different sizes and pitches. If you print it so a ruler matches the inch scale, and you count the threads, it should give you a sense of what your axle size is. I'll post a picture here but the sizing won't be accurate. You will need to download the chart.
Screenshot_20250309-151818_PDF Reader.jpg
 
major masingil said:
I did a quick look at Vivi's website and did not see a specific nut for wheels called out. They have a nice website with a community page and online support. You could probably get the info you need there. Sometimes I'll buy a couple different sizes at the hardware store to see what will work. Not the most efficient method but it usually works. You'll want to pay attention to the threads. They may not be the standard coarse thread type.
Click to expand...
It was actually a store that specialized in fasteners and my bike nut did not fit on any of their bolts. I suspect it is metric and the problem is in the thread. I bought the bike through the internet because the seat height was specified to be as low as 29" (perfect for my 5' 2" wife). But the lowest setting was actually 33" and it came missing the nut. Therefore, don't recommend Vivi.
 
Could be Japanese.

If I recall correctly there are slight differences.
 
I thought Japan used metric fasteners. There is a JIS standard but that pertains to screwheads an hydraulic hose, maybe more. Bottom line is that there are many different thread pitches and thread forms but, my bet is that it is one of the common metric sizes and pitch.
 
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