How I installed the padded seat from the Schwinn 290 recumbent exercise bike on the less expensive Schwinn 230 model

Caveats:

• YMMV. This advice comes with no warranty. It’s based on the 230 I just bought from Schwinn and the replacement parts diagram I just found on their website for the 290. Maybe your bike is different and won’t match. Maybe you’ll cross thread a bolt and ruin it. 
• I’ve only just installed this, so it’s possible it could loosen up or fail in some unpredictable way with further use.
• I discovered this by guessing and taking a chance. I was hoping that the engineering team adhered to a practical standard. I got lucky.
• This happened because I didn’t want to spend money on the extra features of the 290, but when I received the 230, the plastic seat bottom made me sad. It’s not a bad seat! I just hoped I could do better. It remains to be seen if the padded seat is actually better. 

The padded seat bottom for the Schwinn 290 recumbent bike (about $50 at the time of this writing through the Schwinn Fitness replacement parts site) will fit the bolt hole pattern on the Schwinn 230 (the less expensive model that comes with a hard plastic seat) without drilling, but:

1. You’ll need to buy a set of four coarse thread M8 x 40mm bolts along with matching lock washers and regular washers. Hint: take the new padded seat to your local hardware store to check the fit for all four bolts, because bolts come in different thread pitches and different bolts might even be mixed up in the same parts drawer bin.
2. Leave everything as loose as possible until you get the threads started for all four bolts, because the new seat might be off by perhaps a millimeter and require some finagling.  

Cheers, and happy half-assing,

Chickpea Salad Sandwich Disliker