ROB RANTS

BIKE WEIGHTS

Words & Interviews by Robert Johnston

Rob’s Rants Column will be a chance for our tech editor, Robert Johnston to revisit his roots as a Mechanical Engineer and natural Scottish grumpiness to present opinions, raise questions and share his opinion, for whatever it’s worth…Which probably ain’t much.

If we flash back 15 years ago, to the beginning of the Enduro era, we were still finding our stride in the great mountain bike evolution. Cross-country bikes, designed to excel at their intended purpose, were very light but began to fail catastrophically as trails changed and rider’s mentalities pushed the envelope of what could be ridden. It wasn’t just frames that were feeling the strain of these more aggressive riders and terrain.

Punctures were almost guaranteed, as sidewalls and tire development were still in their infancy. Of course, you could overinflate the tires to prevent pinch flats, but considering rubber compounds were still hard as plastic, you’d likely end up on the ground just the same as traction was seriously compromised.

Let’s not forget the angles! Geometry was downright dangerous, with a severe lack of stability that made trails significantly more difficult and likely reduced the potential growth of the sport. As a beginner you were tasked with the struggle of staying confidently on your bike as you attempted to emulate the downhillers and freeriders you’d see in videos on a bike with the stability of a one-legged chair.

As brands began to grow tired of warranty claims, athlete feedback and witness the growth of a new genre of riding, bikes began to evolve and more closely resemble what we’re lucky enough to ride today.

There was a time where a sub-30lb bike was a reasonable target, in my circle at least. You could have a competition amongst friends to see how burly you could go within this weight limit. Compared to the modern crop of enduro rigs, this wasn’t very burly, and I recall a downhill race at Fort William in 2014 when my sub-30lb enduro bike ended up breaking in some form on every single run. Zero completed runs and an expensive repair bill! These days, I’d not really think twice about taking an average “All Mountain” bike down the track with the appropriate tires, so things must have come quite a way.

While the modern crop of bikes have come on leaps and bounds in their capabilities, with enduro bikes rivalling the descending abilities of downhill bikes from not too long ago, it’s come at a price. The weight of bikes has been rising steadily, for example a 2016 YT Jeffsy was a hair under 29lbs, whereas our recent 2021 Jeffsy test rig came in at 31.6lbs. We’re now at the stage where downhill bikes are matching or even undercutting the weight of your typical enduro machines. What gives?! We’re starting to see more and more riders complaining about the weight of “pedal-friendly” bikes rising, but can it be avoided? Let’s try and get to the bottom of what’s happening.

First and foremost, when compared with their downhill siblings, enduro and trail bikes do have a couple of parts that are unavoidably heavier. Droppers and wide range cassettes are partly to blame, and we’re beginning to see in, and on-frame storage become a necessity for riders looking to pedal without a pack. Add in items like remote lockout (or Live Valve/ Flight Attendant) and idler pulleys (with longer chains) and the weight really begins to stack up, but for the most part they are “Essentials” to meet the demands of the modern trail and enduro rider. We’ll let manufacturers off with these.

29ers have taken over almost completely, whether we like it or not. The benefits in roll-over and grip are evident, though it’s not a benefit to all riders and terrain – some can be hindered by the larger hoops, but we’ll leave that for another article. With larger wheels comes higher weight, with extra material required for the tires, rims, and spokes. There are benefits to be had from the larger wheel diameter, so it seems we’ll have to accept this too.

The geometry of bikes has obviously gone longer and slacker over time, and this has a threefold impact (read increase) on the weight of a bike. All else being equal, a longer bike must have more material in between the two wheels to connect it. This increased length then creates longer levers, meaning the frame sees higher stresses for the same applied forces by the rider or terrain and must be reinforced to be strong enough. And finally, the increased stability of a more aggressive geometry encourages riders to go faster, which leads to higher forces applied and therefore further need to add strength to the components throughout. I can’t imagine everyone wants to ride slower, and this kind of geometry is going to continue to evolve (although likely at a slower rate), so this one gets a pass too. Dang.

Component specs for each category are getting more aggressive to keep up with the increased capabilities produced by more stable geometry and better suspension performance for a given travel. The increased suspension demands for each travel class are leading to larger stanchions, a la Fox 38/Rock Shox Zeb, in the forks. Manufacturers are spec’ing bigger rear shocks for more damping consistency and coil shocks on shorter travel bikes. Tire casings are getting increasingly heavy with inserts being added too, as people are favoring the extra grip and puncture resistance over ultimate rolling speed and lower weights.

With social media becoming increasingly powerful, the reputation of companies can be tarnished so quickly by reports of a failure that gets blown out of proportion. With fewer bikes failing as strengths increase, producing a bike that gets a reputation for breaking could have serious and irreparable consequences for a brand. Unfortunately, this means that every rider has to pay the price in the weight of their bikes. Lighter or less aggressive riders will be most impacted by this, likely never getting products remotely close to their stress limits, which could mean a compromised ride. It’s a shame, but it’s understandable.

It all stacks up. A recent weigh-in of a friend’s race setup on his Privateer came in at 39lbs. 39lbs!! Admittedly I don’t think I could break it if I tried, and the peace of mind mid-race would be welcome, but damn. We’re getting close to going full circle back to 2005 freeride bike weights, it’s concerning. Pedaling 39lbs up a hill all day is scary, but I know he’s not alone in that sort of weight figure. This has to stop.

So where and how can we address this? With inserts becoming increasingly protective and weight-efficient, and people requiring the tear-protection of a burlier tire, could we see a shift back towards lighter rims? Do increasingly effective high pivot suspension designs mean we can forget about coil shocks? Will it come down to more intelligent or advanced use of materials in certain areas such as carbon and titanium frames by Stanton or Atherton bikes and fiber spokes such as Berd. Are we adding weight to unnecessary areas of the bike, or could we look to integrate things even more? Integrated cockpits shave a decent chunk of weight, but many dislike the fixed bar roll. An integrated cassette and freehub has potential as Hope have done in the past, but it adds further expense to drivetrain wear. By the looks of it we might need to combine all of the above, and more, to stand a chance of getting the weight of the most capable enduro bikes back down to more pedal-friendly weights.

Then again, maybe it’s just me. Do we even need to address this? For myself, a large 2.25lb or 1kg increase in bike weight adds less than 1% to the system weight, so smooth climbing is essentially unaffected. I can for sure say that my power output and energy levels can fluctuate by more than 1% day-to-day. Technical climbs, where you’re constantly re-accelerating may lead to more energy being used, but the flip side for me is the reduced pressures I’m able to run in a burlier tire mean I get more grip and end up stalling less on a techy climb anyway, negating the need to accelerate quite as often.

Depending on what and how you’re riding on the descents, there’s potential for a heavier bike to use less of your energy to ride down the same section of trail thanks to increased stability (from a greater gyroscopic effect from heavier wheels) and suspension performance. If there is a better sprung:unsprung weight ratio, then perhaps over a ride you may end up saving energy with a heavier bike.

This is all very dependent on the terrain and your riding approach though, with a rider that’s more inclined to be very active with their bike and hop from side to side on the trail, you’ll undoubtedly be using more energy to do so with a heavier bike. And of course, durability is always welcome – I can’t imagine too many people have wished their bike would break more often.

Ignoring efficiency or downhill speed, there’s one clear negative point for the heavier bikes, and one that shouldn’t be discounted from the equation – fun. Not full-speed charging through the rough fun, but the side-hit jib fun; the maximum boost off a tiny lip fun; popping and playing around on a mellower trail and dancing from side-to-side fun. Extra weight sucks the fun from those. And for the times on a technical climb where you’re forced to give it a good bit of body English, a heavier bike will only make things harder, more fatiguing. In the same way that not everyone wants a 63-degree head angle, long travel enduro bike, not everyone wants or needs a heavy bike either, but offering them one to ride may sap enough fun from their local trails that they ride less. I know I’ve shied away from longer XC rides with mates in the past when testing a big burly enduro rig, and I’ve got nearly endless levels of stoke in my fire for any kind of ride.

We’ve learned plenty of reasons to explain why bike weights are on the rise, but to me it still seems wrong to accept it given that manufacturing techniques and materials are only getting better. Maybe we’re reaching a “peak” in the trend, and will begin to see weights drop slowly again as we work back down the scale from overbuilt? To get a look into what the near future holds in the industry, we got in touch with some bike companies to get their opinion on bike weights and what the future might look like.

TLW: What are your personal thoughts on the overall weight of a bike? How important is it and does it keep you up at night? Does it matter more or less in certain categories?
CC: I think bike weight is super important and yes, at times it does keep me up at night. It matters less in a pure park bike situation and most in a cross-country application but generally, weight does affect overall performance, so it is significant in pretty much every category for most riders.

TLW: When you are designing and then spec’ing your bikes for sale, how important is weight versus reliability? Do you think that ratio has changed in the last five years?
CC: Reliability comes first on our list, but you still have to ask the question of how you define reliability and who and what terrain does it need to be reliable for. In no case, with any rider is a frame failure acceptable. The bar is constantly being raised for the level of riding, and therefore, the testing standards that we apply to the frames and complete bikes need to increase. At the same time, there is always a decision to be made of what balance do we want to strike. Is the XC bike truly designed to be a world cup XC champion, or do you go the “down-country” route with the spec decisions? Both are reliable, but there are some performance decisions to be made as to what’s going to perform best for the intended use and the type of customer. The ratio has definitely changed, and slightly heavier bikes in all categories due to changes in overall performance. I would say that it’s just as much a performance choice as much as it is a reliability choice when it comes to increasing bike weight. Will wider rims, bigger tires, a longer dropper, and a shock with a big reservoir shock and high oil volume enable you to go faster in your terrain or are you leaving performance, speed, and enjoyment, on the table by over-biking for the terrain.

TLW: Is weight reduction likely for your future bikes?
CC: Some bikes, yes and others probably not. We are always improving the technologies and lay-up design of the frames so it’s been a trend that we can typically pull some frame weight out between generations of frame models while gaining capability and performance as well as durability. However, the general direction of component development and trends leads to heavier bikes.

TLW: What’s the biggest factor limiting your ability to reduce weight?
CC: In the simplest terms, more material on everything. Longer droppers, wider rims, tougher, thicker tire casings, bigger rotors, larger calipers, and even longer frames. It all adds more material, and you can only optimize the weight out of a part so much when you keep adding material.

TLW: Some say there are certain advantages of riding a heavier bike. Do you agree and if so, what are they?
CC: It’s more planted and stable. There’s corners and situations on my Shuttle E-bike where the bike just sticks and is so planted that I can carry corner speed that my Switchblade simply can’t match. The downside to this is that you still have to stop the bike. There are other corners and situations where the Switchblade is just WAY nimbler, even though both bikes have similar travel and geometry. If you have a chairlift then a bit heavier bike is not necessarily a bad thing. However, if you have to earn those downhills then I prefer the lighter bike in order to make sure that I have plenty of energy left to enjoy the descents.

TLW: What would be your advice for someone who wants to ride longer miles and big climbs but doesn’t want to ride a 36lb bike? Should they go down in travel to a shorter travel bike to save weight? Buy a frame and build it to their needs? Or just quit whining and get stronger?
CC: It depends a bit on your budget, your riding style and where you like to ride. Rotating weight and un-sprung weight are the biggest contributors to making your bike pedal sluggish. If you can get the wheel weight down and still have good durability for your riding style and terrain, then your overall bike weight may not be as big a concern. Generally, you are also able to get a reduction in over-all weight by going down in travel. The components that support a lesser travel can be lighter weight as well. With current bikes like the Trail 429, they aren’t all that less capable in steep, technical terrain, but you will run out of travel faster, so the size of the hits, jumps, or drops as well as how smooth you are as a rider dictate what travel bike you should be on. We have employees at Pivot that need to run, high tire pressure, DH casings and still trash wheels with regularity while on the other end of the spectrum, we have Ed Masters who can pretty much run an EXO+ casing on a light trail bike carbon rim and podium an EWS. You need to know who you are. In some cases, it may be that you don’t just need to get stronger. You need to get smoother! That said, without opening too much debate about wheel size, this is where 27.5 wheels really shine. The Mach 6 and the Firebird are in many ways twin brothers, but one got shorted in the wheel size department. The smaller wheels make quick work of both steep punchy climbs as well as those long drawn out suffer fests because they just turn over easier. With smaller wheels, the bike also gets a shorter axle to crown fork which is lighter and for most riders means they can get away with 36 instead of a 38 chassis, making it even lighter and nimbler, yet overall travel is nearly identical, as is the aggressive reach and geometry numbers making the smaller wheel equally capable when it comes to jumps and big hits. I’m not pushing one over the other, but if your terrain choices and riding style don’t really allow for you to go weight weenie on the wheels and tires, and you spend a lot of time climbing then smaller wheels are also an option to reduce the wheel weight and overall bike weight. Of course, a big budget doesn’t hurt either. The highest end builds also have a more carbon and titanium parts that can often reduce the complete bike weight by a few pounds (1-2Kg) over less expensive builds. In our line, every build is high end and super capable, but the biggest advantage to our Team level builds is lighter weight (and a little more bling).

TLW: What are your personal thoughts on the overall weight of a bike?
JM: Within reason weight doesn’t matter; rider weight dominates, unless we are talking about big differences > 5kg.

• https://www.starlingcycles.com/does-bike-weight-matter/

Wheel weight does matter, although the energy differences to spin up different weight wheels is not significant, I believe that on rough trails, the stopping and starting of the wheels adds up to an increased overall effort.

But this all needs to be countered that heavy bikes/wheels to add to stability. In particular the gyroscopic stability of a heavy wheel/tire adds to control in rough terrain. Downhill tires work better not just because they are tougher, but because they are heavier! So, wheel weight/tire choice is a compromise between pedaling/climbing and rough terrain capability.

TLW: When you are designing and then spec’ing your bikes for sale, how important is weight versus reliability? Do you think that ratio has changed in the last five years?
JM: Personally, I really don’t consider weight too much when designing a bike. Obviously, we don’t spec, silly weight additions; solid tubes for example, but as long as design decisions only have small delta in weight, we do not use it as a design driver.

However, weight is still a marketing metric considered by many as important. So, even if the science says it doesn’t matter, it would be stupid to ignore it as it may affect sales.

TLW: Is weight reduction likely for your future bikes?
JM: Nope

TLW: What’s the biggest factor limiting your ability to reduce weight?
JM: Strength, toughness, and reliability.

TLW: What would be your advice for someone who wants to ride longer miles and big climbs but doesn’t want to ride a 36lb bike? Should they go down in travel to a shorter travel bike to save weight? Buy a frame and build it to their needs? Or just quit whining and get stronger?
JM: Weight doesn’t matter; but as discussed wheel weight does. So, spec a nice lightweight set of wheels.

But then consider all the other effects that contribute to energy losses;

• Tire drag (run fast rolling tires and high pressures)
• Mechanical efficiencies (clean and lube your chain, ensure good chain line, ensure wheel bearings, and bottom bracket run freely)
• Suspension losses (ensure your suspension is not robbing energy, stiffer shorter travel does this effectively)
• Aerodynamic losses (get your head down especially in the wind)
• Good ergonomic efficiency (ensure your bike fits well and is enabling you to pedal as well as possible)
• Fitness (get fit and strong, and fuel yourself well).
• The list could keep going…

TLW: What are your personal thoughts on the overall weight of a bike? How important is it and does it keep you up at night? Does it matter more or less in certain categories?
GB: For us it’s all about intended use — the closer the bike is to being a full-on XC racer, the more we’re concerned about weight, and there is certainly lost sleep over this. The further we venture towards the more aggressive side of mountain biking, the less we worry about pinching grams. In fact, many professional downhill racers add weight to their bikes for certain conditions…

TLW: When you are designing and then spec’ing your bikes for sale, how important is weight versus reliability? Do you think that ratio has changed in the last five years?
GB: We’ll always err on the side of durability and reliability over weight savings. We’ve designed our bikes this way for years and I wouldn’t expect this to change.

TLW: Is weight reduction likely for your future bikes?
GB: Where applicable and necessary, yes– who doesn’t love to ride a peppy little rocket now and again?

TLW: What’s the biggest factor limiting your ability to reduce weight?
GB: Durability. Building featherweight frame parts isn’t outside the realm of possibility these days, but there’s a balance. We build bikes to last a lifetime, and we don’t like weight limits, so we walk the line between reasonable, competitive weight targets, and making sure to build parts that hold up.

TLW: Some say there are certain advantages of riding a heavier bike. Do you agree and if so, what are they?
GB: Sure, a bit of weight down low has the tendency to ‘settle’ a bike a bit, which can be quite nice in certain conditions.

TLW: What would be your advice for someone who wants to ride longer miles and big climbs but doesn’t want to ride a 36lb bike? Should they go down in travel to a shorter travel bike to save weight? Buy a frame and build it to their needs? Or just quit whining and get stronger?
GB: It’s all about priorities. For me, the first priority is to ensure the bike can happily stand up to whatever violence we expect once the climbing is done. Luckily, modern geometry and good suspension design make it so capable bikes are pretty comfortable climbing all day. There’s a nice middle ground — for Santa Cruz this is Hightower and Bronson territory — where aggressive geometry and plenty of suspension travel meets efficient, comfortable climbing. With lighter casing tires (like a Maxxis EXO) you can get into the lower 30’s pretty easily, while throwing on a pair of DH Casing tires turns the same bike into one you could abuse in any bike park. We can’t expect a 150mm travel bike to climb like a Blur, but if descending is a priority… get stronger! Want inspiration? Look to Ben Hildred and Margoux Elliot …

TLW: What are your personal thoughts on the overall weight of a bike?
DS: I think it’s important and definitely a major consideration in the construction of a design, but I do think that it should stay in the place of second fiddle to product reliability.

Longevity of product also includes considerations in relation to sustainability and safety. We saw in our industry an average of 2 carbon frames made to every 1 carbon frame sold from Asia-made bicycle companies, all competing in the weight-race to get an Enduro complete bike under the 29lbs mark. Failure rates on frames were through the roof, people were bikeless waiting for new frames to come through and contention and irritation became a staple interaction between the consumer and Bike Shops who play the mediator.

TLW: In your opinion, does the weight of a trail bike matter?
DS: Yes, but it should not be the single defining factor. I believe Pedal efficiency (light ride feel) can be gained through tight tolerances in the assembly and in the kinematic layout of the design.

TLW: What about an enduro bike?
DS: The same principles expressed in the above question apply across all bicycle frame design.

TLW: When you are designing and then spec’ing your bikes for sale, how important is weight versus reliability? Do you think that ratio has changed in the last five years?
DS: Personally, when spec’ing a bike, I feel that the smartest place to save weight is a good wheel set, as the wheel is at the end of the lever, so Extra weight and poor rolling resistance is instantly noticeable in the maneuverability of the bike.

TLW: Is weight reduction likely for your future bikes?
DS: We are now offering carbon rear end with titanium fronts on our FS (full suspension) frames, this has drastically shed weight off our FS products but without any compromise in relation to strength, in fact the product is stronger! However, the compromise has to fall somewhere and so in the trifecta between price strength and durability it is the price aspect that bears the brunt.

TLW: What’s the biggest factor limiting your ability to reduce weight?
DS: The value of which the market is willing to pay for a product and preconceived cultural expectations in relation to materials.

Although carbon for front triangles can reduce weight dramatically when focused on unidirectional forces such as horizontal and lateral, the real-world application for MTB frames exposes the frame to multiplicity of different forces, and torsional stresses and heavy impacts! Thinning out carbon frames to drastically take out weight makes them prone to damage in real-world scenarios but makes the frame extremely light. However, as I said before the failure rate when used in real world application is extremely high and so now the material has gone back into the frames to stop fracturing and now Carbon bikes are back up in weight.

On our switch9er Titanium FS we’ve spent an absolute fortune on R&D and we’re trying our best to meet the customer at a price point they’re happy with. The direct to the consumer business model helps this as there is no distribution company and no shop to count in on the margin.

This means that you can pay more for the research and design and development of your products and the overall cost of your products.  Our switch9er Ti Carbon is a very light product and extremely durable! The use of titanium for the front triangle means that we can create lifetime products. Dents scratches even cracks can be repaired very simply.

TLW: What would be your advice for someone who wants to ride longer miles and big climbs but doesn’t want to ride a 36lb bike? Should they go down in travel to a shorter travel bike to save weight? Buy a frame and build it to their needs? Or just quit whining and get stronger?
DS: Personally, I think you should buy a Switch9er FS Titanium as my complete bike comes in at 31 Lbs with an EXT coil shock and EXT forks. Titanium in my opinion is a wonder material, it has an extremely high elasticity which drastically reduces Trail buzz, it’s also epically strong and hardens on impact. It’s also easy to repair and looks brand-new after a rub with scotch bright. We went with Carbon for the rear and added extra layers of Twill (multi directional) to its design to make the back end super stiff and super strong in all directions.