It's fascinating to see the change that climbing is going through, with so many disciplines to choose from. Indoor climbing has become a distinct genre in itself, and not one that necessarily cross-pollinates with the likes of bouldering, sport or trad climbing outdoors. As such, it's quite a challenge to create a shoe that'll fit the needs of every climber - especially if you factor in that 'urban factor' (i.e. fashion), which will be of interest to some more than others. The Prime goes for looks first and performance a distant second, making it most suitable for the urban environment. It's not the most technical shoe, by a country mile, so it's never destined to be seen at the top of the mountain, but as far as cragging in accessible roadside locations is concerned it's got enough - just.

Functionality

The Prime sits right out at the softer and less technical end of the approach shoe spectrum, with quite a casual appearance and a flat lasted construction. Our recent review of the Fuel, currently Black Diamond's most technical approach shoe, found them too soft and bendy to really recommend for use on UK scrambles and mountain crags, and that goes double for the Prime:

With the current range of approach shoes Black Diamond's designers seem to have gone all out for softness, and we sadly think this makes them only of borderline usefulness for your average UK (outdoor) climber.  

Whilst the term 'approach' was originally used in reference to approaching mountain crags, it could be argued that the Prime was designed with approaching the climbing wall in mind. Yes, their Guide Tennie-esque dotty rubber sole is great on slabby rock; however, in the UK we tend to have to approach said rock through wet, muddy and grassy terrain, and this can be lethal in flat, dotty rubber soles (he says, having skated down various hillsides at terminal velocity wearing them over the years). If you're on tracks or well-drained trails then you're going to be OK, but on rough terrain you're realistically going to want something with a lot more bite underfoot. In addition to this, they're not the most supportive or structured of shoes - to make the understatement of the month - so even if grip wasn't an issue, long approaches probably would be, as there simply isn't enough substance to make it comfortable over distances. 

Fit

The Prime comes in both men's and women's models, so we've looked at both to get a good overview of the fit:

Mens: The Prime come up quite small for their size. I ended up getting a pair that were the same as my street shoe size and they were concerningly snug to begin with, but loosened up after a bit of use. Ideally I'd have liked to have tried on a half size up, as I have a feeling that would have been perfect, but given Penny's feedback regarding stretch (and the fact mine gave) perhaps that wouldn't have been necessary after all. When it comes to width they're pretty much bang on the middle, and ditto for volume. 

Women's - Penny: Unlike Rob, I did go half a size up, and am now unsure as to whether that was the right decision or not. In the short term it made them feel quite comfortable out the box, but in the longer term I think they've stretched a bit, making them feel a little larger than I might have liked. In terms of fit, the Prime are an interesting one, because they're so soft that I'd almost say they mould to the shape of your foot. 

Upper 

The Prime features a lined suede upper and comes in a variety of different colours (two choices for both men and women). All of the stitching is reinforced and, at least throughout the use we've given them, has lasted well. Our suspicion would be that the uppers will last at least a single resole, possibly more - especially given our experience with the Black Diamond Session, which lasted impressively well): 

The flat laces give good adjustment and the padded tongue keeps the shoe feeling nice and comfortable. There's a clip-in point on the back of the shoe, which is useful if you're out multi-pitching, then a large rubber rand around the front, which is reinforced to provide an extra degree of protection for your toes whilst you're climbing, or approaching across rough and rocky terrain.

Sole/Midsole

The Prime features a flat, dotty rubber sole featuring Black Diamond's BlackLabel Street rubber. This is the same compound that was featured on the Session Approach Shoe last year, and this has - for a sticky shoe - worn incredibly well. Soles of this kind are at their best on rock, where they're supremely grippy (think Yosemite, Squamish etc…); however, as we cannot say often enough, the issue is that in the UK we often have to cross fairly unfavourable, wet terrain to get to the rock, which is undoubtedly where the dotty rubber is at its weakest. 

The Prime features a soft EVA midsole, which favours sensitivity over support. Whilst it feels fine on shorter, less technical walk-ins it doesn't feel like it offers enough support for longer, tougher and rougher approaches due to its flexibility - or even middle distances for that matter. As such, if you are looking at these for UK cragging it's probably worth thinking about where you're going before buying them. If it's shorter walk-ins on tracks and trails (think sport climbing at Kilnsey, bouldering at Burbage etc…) they'll be fine, but then a pair of sandals or any old shoe would do here. If you're looking to approach more remote crags over rougher terrain it'd realistically be worth buying something beefier.

When climbing or scrambling their softness helps get lots of shoe onto the rock on slabby ground, but they're so bendy that they feel about as much use as a pair of flippers on small edges.

Aside from the lack of end-to-end support its also worth noting the lack of lateral support from side to side. More technical shoes tend to have a rock plate of some sort, which helps to protect your foot from (as you might have guessed) rocks and stones that stick up, but the Prime doesn't have anything like this, which further cements their role as indoor/urban only in our eyes.

Weight

At 300g (Men's UK8) and 260g (Women's UK6.5) they're actually quite light for an approach shoe, but given the lack of support this may not be too much of a surprise. 

Summary

Whether or not the Prime is for you largely comes down to what you're looking to use them for. They sit right out at the softer end of the approach shoe spectrum, being more casual and urban in nature, and as such they do push the definition of 'approach shoe' towards destruction. If you're off down the climbing wall then that's fine, but on grass, mud and quagmires this extremely bendy, flat-soled shoe performs very poorly, while its lack of support means that it isn't going to be a natural choice for longer walk-ins. In the Session, Black Diamond already had a really decent soft shoe, and one that I like a lot. With that existing model in the range, we think they'd have done better with the Prime, and indeed the Fuel, to concentrate more on support. It looks nice though, which may be the most important consideration for some.

Black Diamond say:

Engineered for ultimate comfort without sacrificing durability, the Prime features a suede upper that allows for an adaptable fit while providing added weather resistance and comfort. The Prime can also handle approaches with ease thanks to its BlackLabel-Street sticky rubber outsole. Rubber toe adds protection, and the webbing loops allow for various tagging and stowing options for when the trail ends and the climbing begins.

• Sizes: 5-13 (men) 3-8.5 (women)
• Durable lined premium suede upper
• Black Diamond BlackLabel-Street sticky rubber outsole
• Rubber toe protection
• Toe shape and upper construction inspired by climbing shoe construction
• Super comfortable molded EVA midsole