Mano a Mano
Is Cushcore Preferable to a Heavier Tire Casing?
Tire inserts have generated a lot of discussion since their debut in mountain biking. It was revealed in 2017 that Aaron Gwin had used Flat Tire Defender for his downhill runs for an entire season without anyone knowing. The factions are polarized, even among riders who have never ridden on an insert. Some riders think inserts are only for racers, but there's another camp that refuses to ride without them. I’ve spent time on both options from Cushcore and, more recently, Rockstop, which I'll have a review for soon. During this process, a question kept coming up over and over: Can a tire with a heavier casing achieve the feel of a lighter one with an insert?
That question has stuck with me and late last year I did some testing to try and find out. After organizing some Maxxis tires – Assegai (front) and DHF (rear) – in various carcass options, I was ready. The Whistler Bike Park provided the best chance at the daunting task of getting the tires tested in a day, and offers a variety of terrain in a single lap. The test track was originally set as Schleyer, Lower Whistler DH and Heart Of Darkness. Come test day in 2019, Mother Nature had different plans and with conditions freezing overnight, Schleyer and its neighbouring trails were shut.
Another loop that remained mostly in the trees with less water was put together to limit encounters with frost and ice. After a short puzzle of what was open, I opted for Upper B-Line over to Ninja Cougar, Karate Monkey, Samurai Pizza Cat, Afternoon Delight to Tech Noir, and finally Heart of Darkness. This was the best loop to provide me with a bit of everything, considering the limited options. Schleyer and Lower Whistler DH have more of the speed that I was looking forward to testing with but after a quick lap of the reroute, I found rim in a couple of spots. The tight, fast corners on Ninja Cougar also provided a great opportunity to test tire support. For consistency, I used the same route when I repeated the test this year.
Unfortunately for me, the wheels I was riding last year during the test threw in a curveball – and left me with very sore fingers. A set of Spank 350/359 Vibrocore wheels adorned my bike during the initial test and the damping qualities of the foam-filled hoops made isolating that same attribute with the Cushcore added, difficult.
I thought the earlier test would have to be binned so a year later and with the perfect set of wheels for the test, I headed up to try again. On the same test loop, but with a set of remarkably unremarkable WTB KOM 29 rims, I was better able to identify the differences between the two combinations. Many of my thoughts from the initial test were validated but it was easier to pinpoint the changes with the WTB rims.
Having spent the last few years mostly on Maxxis tires, it made sense as the rubber of choice. Maxxis offers a strong selection of casings and I decided to go with the EXO+, Double Down, and DH options with the aforementioned Assegai out front, my preferred front tire since its release, and DHF for the rear. The DHF was available in each casing and used to be my go-to front and rear tire. I also spent time on the DD and EXO+ Assegai for a long term review last year.
Cushcore now makes two versions of their insert; the XC which has less volume and weighs around 150 grams and the original, now called the “Pro,” which weighs ~265 grams. I opted to go for the original because it makes a more pronounced change to the feel on the trail. My GeoMetron/Nicolai G1 remained the same as I ride it every day to start with but my suspension settings required adjustments during the test.
Leading up to the test I’d mostly been riding the Assegai and DHF in Double Down casing. I've also spent time on a High Roller II and Aggressor this summer, and more recently a set of Michelin Wild Enduros, but last year and for a good portion of 2020, my tires have remained Assegai/DHF. In the summer and usually in the park, my tire pressures bump up to 22psi front and 25psi rear with the Double Down setup. Once things get wet and slow down they can drop as low as 20psi (front) and 23psi (rear).
Time to Smash
One major difference from last year to this test is that the Spank Oobah rim profile makes insert installation a tad difficult. After plenty of time in the Whistler Day Lot wrestling with setups last time, my fingers hurt for days. Things were easier with the WTB KOM wheels and the above freezing temperatures. Add a set of Cushcore Pro inserts that had been lightly used and I was able to mount them without the hammer handle method.
EXO+ and Cush/EXO+
Before the inserts went in for the first time, I rode a scouting lap on EXO+ casings to check conditions and feel out the bike for the day. Everything was close to ideal and heading for a second lap, I focussed on the tires and keeping my riding at about 80%.
Before the latest test, I'd spent a few rides back on my Double Down tire setup. The EXO+ carcass offered less support with the same pressure so I bumped up to 23 and 26psi. This felt comfortable on the trail but I hit the rear rim once and noticed the bike stall slightly in a couple of the choppy compressions on Ninja Cougar and Afternoon Delight.
With the inserts installed, I was able to maintain momentum better through these sections, highlighting the issue from the previous lap. It felt great and added a sense of seamlessness when connecting sections of the trail on either side of the ugly (or fun, depending on your jam). It felt faster too. The EXO+ tires with Cushcore Pro were also noticeably stiffer and felt similar to bumping up to the heavier casing. When the inserts were installed, I dropped pressure to 21 and 24psi.
Double Down and Cush/DD
With the Double Downs set to the same pressure as the Cush/EXO+ – 21psi front and 24psi rear – the bike immediately felt more comfortable on the first section of the loop, a mildly beaten B-Line. It made the previous run with the Cush/EXO+ through the same section feel rough by comparison – I was shocked. The Double Downs were more than 100 grams lighter than the Cush/EXO+ while tire stiffness felt similar when generally playing around.
As I progressed down the test loop, the lack of an insert became more apparent. While the wheels felt more comfortable in general bike park conditions and terrain, they were less so through rock armour or compressions with rock-strewn throughout. As with the laps on the EXO+ above, the support of the Cushcore was sorely missed in these situations and with the DD carcass, both rims pinged the ground; once in the same spot and another to only the rear.
I didn’t use a stopwatch but the inserts felt quicker, smoother, and more supportive through sections with choppy, sharp edges. Coming into fast rock-armoured sections without the insert, the wheel felt less composed and the rim pinged off the ground. In other situations, the absence of insert was less noticeable and I quite liked the feel in all but the rougher situations. Inserts considerably stiffen the base of the tire and when not pushing hard into the wheels, they felt harsher than the heavier carcass without.
Inserting the Cushcore into the Double Down tires, the added weight was easily felt. The unsprung mass caused my bike to feel sluggish and required changes to my damper settings. Pulling out of the bike quickly – bunny hops and similar, aggressive extensions – resulted in the engagement of the top out in both the Öhlins RXF36 m.2 coil and EXT Storia V3. I slowed the rebound at each end – eventually to a total of two clicks – to compensate while still maintaining grip. If I'd spent more time on the setup further damper adjustments would have been made.
I didn’t go too low with tire pressure, settling on 20psi front and 23psi rear. In other tests, I’ve found 3 psi to be my max change with the Cushcore. When I go lower than that the tread squirms too much and bottoms too quickly into the dense foam material. But the 1 psi change I made wasn’t enough and the tires felt too stiff. They also presented a more dead feeling than the DD without inserts. Similar to the Cush/EXO+, when I pushed the bike hard through sharp compressions with uneven rock, the Cushcore setup was more composed, preserving more momentum and damping more of the feedback.
CUSH/DD to DH
COVID made for a slow lift line and I was quickly running out of time. With more time I would have taken a second lap with the Cush/DD at a lower pressure. With only the DH tire left to install and enough time for one more lap, I quickly ripped off the Cush/DD setup and installed the heavy-duty Maxxis DH casing. Tire pressures started at 20psi and 23psi as with Cush/DD.
On the trail, the downhill casing tires produced sharper feedback than the Cush/DD setup. They felt less comfortable everywhere with the thicker, 60 TPI carcass not able to conform to the terrain as subtly as the lighter 120 TPI casing of the Double Down tires. During other recent tests, I’ve found the higher 120 TPI thread count more comfortable, regardless of the rubber compounds in the tread or layers in the carcass, but that’s for another article.
Despite the tougher tire casing threaded with thicker gauge cords, the rim still connected with the ground and when pushed hard in the wrong situation, quite easily. Grip and support were great but I wanted to see if the feedback could be cut down. The tire also felt quite stiff and I opted to drop the pressure slightly, finishing the run with 18.5psi front (I was aiming for 18) and 21psi rear. This helped with comfort on the trail but the Cush/DD still had more protection and maintained more speed more effectively through the rough.
Both the Cush/DD and DH setups produced more feedback in one section of Afternoon Delight; a right-hander that starts out of a mild compression but has some sharp hits in the corner to jostle the bike. The DD and Cush/EXO+ setups were most comfortable here. This is likely due to the fact that I am used to riding Double Downs.
Conclusions – Sort Of
The most interesting discovery was jumping from the Cush/EXO+ to the Double Down without an insert. I didn't expect the standard DD setup to feel more comfortable in general riding situations. It wasn’t until hitting rock armour at speed or pushing the bike through compressions riddled with sharp edges that I felt better with the insert in the lighter carcass EXO+ tires. This partially answers the question behind this experiment while also making it clear that the terrain you ride in most often is an essential part of the equation. Cushcore's benefits are clear for many riders but if your trails don’t have ample rough terrain and rock-filled compressions, the advantages are less clear.
The Cush/EXO+ and Cush/DD setups damp trail chatter but the stiffer ride they provide also has an effect on feel. Being more experienced with Double Down tires, I preferred the feel of the Cush/EXO+ to the Cush/DD because the added weight and stiffer tire took some getting used to, while the Cush/DD tire setup felt more comfortable than the DH tires alone. I can only put this down to the DH tires stiffer overall carcass and thicker, 60 TPI construction.
While I focused more on trail feel, there's more involved in the decision-making process; cost, personal preference, and rim protection to list just a few. The protection Cushcore offers is a selling point for most riders and while their damping qualities are more pronounced in some situations, it may be that tire support and rim protection are more important.
That’s not black and white either though. Outside of the test, I spent some time on an EXO HR II with a Cushcore Pro installed and fell victim to a classic pinch flat. Thankfully it was at the tail end of the ride because I wasn’t keen to remove it trailside and it would surely have been an issue finishing the trail with it hung over my torso – a disadvantage of Cushcore. Instead, I left it in and bounced down the rest of the trail. I was able to pedal back to the car with minimal problems though which is another advantage of Cushcore.
There’s a huge crowd of people who swear by inserts but recently I’ve come across more riders who don’t feel the benefits are worth the cost or faffing involved. Whether that be installation or dealing with them when something goes wrong during a ride, some riders are moving back to heavier duty tires, sans insert.
Which camp are you in?
Ape Index: 1.037
Trail on Repeat: Changes as often as my mood.
Current Regular: Every test product spends time on Entrail