I need some new calipers on my disc road bike and, as it’s post mount, I am looking at the Shimano MTB range.

I was looking at the difference between Deore, SLX and XT. The money in it isn’t huge, but what are the benefits? Is it just weight? Longevity? Or does the actual braking performance (which is what I am interested in) improve?

Caliper wont contribute to braking performance. All it does is clamp the pads onto the disk. The pad doesn’t know or care what caliper is applying the force to it, all it knows is how much force is being applied. In combination with the lever it will affect how the braking feels to the rider who will then interpret in a subjective way if the new caliper is better performing than the old caliper or not. But that is not necessarily to say that how the brake system feels to the rider is unimportant…just the opposite. I suspect the price difference between the callipers in the Shimano range are 3% weight benefit, 30% bling and 67% marketing.

I swapped out the 105 calipers on my road bike with Hope RSX’s. They are 3% lighter, 90% blingier and 7% better performing in conjunction with Hope floating discs and pads which contribute 90% of the 7% performance improvement. As far as feel goes, which is what is important to me, bite feels more positive than the shimano caliper/pad/disk combo, modulation better. Overall a worthwhile ‘upgrade’ but not that much wrong with the previous setup really. Just felt a bit crap to me, but fundamentally did a good job of stopping me when I wanted to stop.

Most of the difference between Deore, SLX and XT is at the lever end – either more adjustment, or no need to use a separate tool for adjustment.

Not sure about the latest M7100 SLX and M8100 XT versions, but there were some subtle differences at the caliper end in the earlier generations. IIRC, Deore don’t get the heat resistant pistons, so more potential to cook the fluid on long descents. Deore use a threaded hose connection which goes to the inboard side of the caliper vs a banjo connection to the outboard end of the caliper in SLX and XT. SLX and XT get a pad retaining screw as opposed to the split pin you get with Deore (though the hole in the Deore calipers is threaded, so the screw is an easy retrofit).

Caliper hose connection is the most important thing to check, as changing hoses is expensive. If you want some SLX calipers, I have a pair around 1 year old, working fine when removed but recently swapped for some bling bling Hope RX4 calipers, £25 posted.

I’d consider the Hope RX4 over any Shimano calliper other than XTR with its 3 year warranty.