Zippa DH Chain Guide

Either — it covers both. It bolts straight to ISCG05 tabs if your frame has them, and the ISCG05 adapter included in the box lets it mount on a threaded BSA bottom bracket if it does not. The one case it cannot cover is a press-fit frame with no ISCG05 tabs: there is nothing to bolt to and no threads for the adapter to grip.

The bash plate. Both share the same CNC'd AL6061 backplate, top guide and bottom roller; the DH adds a replaceable bash plate underneath and a fully CNC'd AL7075 pulley, and comes in at 175g against the Zippa AM's 120g. Put simply: the AM keeps your chain on, the DH also stops your chainring taking hits. That is why this is the downhill and bike park version.

32T to 38T, single ring. The bottom roller sets the lower limit — it has to sit under the ring and hold the chain wrapped, and below 32T the geometry no longer works. If you run smaller than that, the Zippa Lite ISCG05 covers 26T to 36T as an upper guide only, though you give up the roller and the bash plate to get there.

No — the bottom roller is the reason. It holds the chain at a fixed distance from the chainring, and an oval ring's effective radius changes as it turns, so the roller cannot track it. If you want to run oval, the upper-guide-only Zippa Lite models are the ones to look at: with those you just count the ring as two teeth larger than its stated size when you check the range.

Yes, and it is meant to be — it is the part that takes the hits so your chainring does not. Every component on the Zippa DH is individually replaceable, the bash plate, the top guide, the pulley and the hardware, so a chewed-up plate is a spare part rather than a new chain guide. It is worth checking its bolts after any hard impact.

For most trail bikes, yes — the Zippa AM gives the same chain retention at 120g without the bash plate, and the Zippa Lite ISCG05 does it at 30g if you are counting grams. What the DH's weight buys is a bash plate and an AL7075 pulley, and those earn their keep on downhill and bike park runs where a dropped chain or a smashed chainring ends the day. Match the guide to the riding rather than to the scale.