I had a hybrid that I broke two spokes on in two separate occasions.

So, under the advice of some LBS I got a mountain bike - Giant Upland SE, but I got it 2nd hand from ebay. After about 100km on the MTB I broke another spoke.

I have another wheel that I bought from the local op shop because I thought it looked really solid and it was only $5. Is there any way of knowing if it would be stronger than the original wheel? Here is the only writing on the op shop wheel:



My other question is I seem to 'bounce' sometimes without realising it for a while. When I do realise I change to a higher gear but could the bouncing be putting too much pressure on the spokes?

I am really enjoying cycling but I can't spend much more at the moment, and I definitely can't keep replacing spokes every few weeks.