Long term test: BH Lynx 4.8 29

Words by Chris Southwood | Images by Flowtographer

The not-so-minor details

Product

BH Lynx 4.8 29 (frame only)

Contact

BH Bikes Australia
www.bhbikes.com.au

Weight

2.35kg

Please note

Weight is frame and shock only.

Positives

Low weight.
Spot-on geometry.
Attention to detail.

Negatives

Rear end displays some flex.
Shock is exposed to debris.

Back in September we took delivery of the BH Lynx 4.8 29 as a bare frameset. Nude. Curvy. We built it up with a stack of high end parts for a long-term test, and now over four months later it’s time to deliver the report card.

BH Lynx 4.8 29 frame-9

The BH might strike you as an obscure choice – why not opt for a frame from some of the better known manufacturers? While the brand is still on the rise in the mountain bike world, after testing the complete bike in mid 2013 we were quickly convinced that this machine had the cred to hang with the big boys. The bike has simply wonderful geometry and impressive attention to detail that is not normally found in the first generation of a bike.

The combination of very low weight, 120mm of very supple travel, a slack head angle and the shortest chain stays we’ve found on dual suspension 29er make for an amazingly fun ride. It climbs with the best of them but simply floats in the rough incredibly well.

We’re not going to dwell on the ride of the bike too much here – as it’s normally available as a complete bike only – but we’ll focus more on what it’s like living with the BH long term and any quirks or real highlights we uncovered.

BH Lynx 4.8 29 frame-28

The headset bearings sit directly in the frame – Lighty Mclight.

Our frame was supplied without a shock and we opted to run a Rockshox Monarch RT3, rather than a FOX CTD that comes standard on the complete bikes. With shock, hanger, rear axle and seat post collar fitted, the frame weighed in at 2.35kg. If you’re not the kind who keeps a track of comparative frame weights, this is a seriously impressive figure, only a couple of hundred grams more than the industry leaders.

BH Lynx 4.8 29 frame-29

The only significant bits of metal in the whole frame are the aluminium rocker links.

The only frame element that is not made from carbon is the upper suspension links (and pivot hardware, obviously). Even the headset bearings sit directly on carbon and the bottom bracket is a press-fit too, so there’s no need for a threaded alloy insert, saving weight.

BH Lynx 4.8 29 frame-23

Let’s Torx about it. The pivot hardware is all alloy with Torx fittings, excluding the upper shock bolt which is steel.

All the pivots and shock bolts use Torx head fittings in a variety of sizes which required the purchase of a few extra Torx bits of for our ratchet set! A tender hand is needed as much of the pivot hardware is alloy – don’t over-tighten it.

It’s interesting to note the offset of the rear end. In order to squeeze in the front derailleur with short stays, the rear shock has asymmetrical mounting hardware. Crafty. We never fitted a front mech, running SRAM’s XX1 drivetrain instead.

BH Lynx 4.8 29 frame-12

The shock is rather exposed to debris, sitting in close to the rear wheel. As you can see, it’s not actually mounted to the mainframe, ‘floating’ between the chain stay and the upper link.

The shock is situated very close to the rear wheel and this does raise concerns about durability and potential damage to the shock shaft from rocks or lumps of wet clay etc. We toyed with the idea of fashioning some kind of guard to protect it, but it proved too tricky. So far our fears have been unfounded, but we’d recommend giving this area around the shock shaft a regular clean to prevent build up of mud. The shock itself is only a little fella too, with a 1.75-inch stroke (44mm) to help fit everything into the constricted space.

BH Lynx 4.8 29 frame-32

There are external cables mounts for the rear brake and the shock lockout, while the gear cables are all internal.

All the cabling, save for the rear brake, is internal routed with guides inside the frame so threading the housings is easy. There are also external cable stops for a remote shock lockout if that’s your bag. We like the fact the cables and brake lines are routed right over the main pivot, minimising the amount of bending the lines undergo during suspension compression.

BH Lynx 4.8 29 frame-25

Internal cable routing for the dropper post exits the underside of the top tube, making for quite a tight bend.

Like other interrupted seat tube frame designs, the BH is not compatible with ‘stealth’ style internally routed dropper posts. Instead, the dropper post cable ducks in on the left side of the head tube and pops out about three quarters of the way along the top tube. This works ok, but it does force the cable into a pretty tight bend which adds friction at the lever. Keep the cable well lubed for slick running, or run a hydraulic post instead.

One area where the frame is underdone is protection. There is no chain slap protector included and the fat down tube is awfully exposed to rock strikes – fit a Frame Skin kit at a minimum to give the bike some protection.

BH Lynx 4.8 29 frame-21

The rear shock pierces the seat tube. This arrangement allows for a compact overall bike, while still providing room for a water bottle.

To get the most out of the BH on the trail, set up is important. With the relatively slack head angle (for a 120mm 29er) a short stem is best to keep the handling nice and responsive. We went for 70mm stem. The slack seat angle can potentially cause problems too if you need to run a lot of seat post extension, pushing you back behind the bottom bracket. Look for a post without any offset, so you’re not too far off the back, or you’ll be running the saddle rails right forward in the post.

BH Lynx 4.8 29 frame-24

Dave Weagle is the man behind the Split Pivot suspension design. It uses a pivot around the rear axle, identical to Trek’s ABP system.

Our frame was a pre-production model and we did notice the rear end had loosened up a little after a few months, with some flex evident at the Split Pivot assembly. There have been revisions to the carbon layup on production bikes with a little more beef added here (and in the seat tube / top tube junction). Because of the rear end’s feather light construction, this will never be the stiffest frame out back and heavy riders will want to keep an eye on the Split Pivot hardware which is secured with a 12mm Allen key – solid stuff!

BH Lynx 4.8 29 frame-19

Keep the Split Pivot hardware tight! We found this to be the only real area of significant flex in the bike.

BH Lynx 4.8 29 frame-27

Swoopy, like a porpoise.

After four months of riding, we’re still as impressed by the BH 4.8 29 as we were on that very first outing. Living with the bike day in, day out we’ve found precious few niggles with the bike that could dampen our enthusiasm for the way it rides. With the weight of a cross country race bike, the geometry of an all-mountain beast and a level of attention to detail that isn’t often seen, it’s a real standout.

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