What headsets can be used to replace the FSA No.57/No.61BP headset? I managed to damage the headset on my Merida Speeder 300. In particular, I warped the bottom bearing, and I need a replacement. Normally, this would be a simple matter of looking up the specifications of the model in question, except the FSA website doesn't list a product numbered 61BP or 57/61BP.

I took a caliper and measured some of the parts. The steerer measured 28.4mm at the top, and flared to 39.8mm at the crown. I probably messed up the measurements, and that steerer is a 1-1/8"-1.5". The cups are semi-integrated, the top one measured 40.1 mm on the inside, and 32.4mm inside the lip. The bottom one was 47 and 41 mm on the same. Of course, I couldn't get at the tube because the cups were in the way, and my handling of the caliper is suspect..

So, what is this product and what are the critical measurements of it, with an eye to getting a replacement.
I received an email from FSA customer support:

Thanks for contacting us.
Headset No.57/61BP is a cheeper headset with retainer bearing, we don’t have this Headset in stock and also this type of bearing as spare parts.

We suggest to install the below upgrade version, so in the future you can replace only the bearing:
130-0026            HS SX Pro (I/I) 15mm alloy 1-1/8 1.5
Hope this can help.
Ciao
Stefano

Googling this, I found a headset called FSA Gravity HS No. 55 SX Pro, which has the following specs:

Upper headtube ID 44mm
Lower headtube ID 54.92mm (Follow-up email indicates that this is in fact 55)
1 1/8&quot; to 1.5&quot; tapered steerer
50-61mm headtube outer diameter