Please help - 2002 Shimano Deore LX Rapidfire SL

[Retrorockit]

I would say that bike probably came with a 48t chain ring. if you get a 48x104BCD ring you should be OK. I've run 48t with a 32t mid ring and it shifted just fine. I did bump the small cog up to 28t, but it might not have been needed. Touring sets came with 48t back in the day, but MTBs went to 44t and those became the standard. In the US Surly makes some nice stainless steel ones. Shimano in that size has always been kind of scarce. The Shimano inner, and mid rings do have a different size register on the crank set. Many modern cogs are sized for the mid position. But I ran a 48t LX ring on an XT crankset on my street XC bike. The radius on the front derailleur cage is larger too to match the bigger cog. The LX stuff was steel, the XT was alloy.
I see a lot of 10 speed LX 48t rings for sale. The inner dimension of the 9,10,11s chains are all the same. Should be OK.