THE NEW SE6 & SE5 TEAM ISSUE TLR TIRES
Words by Drew Rohde
Video by Brian Niles/Treeline Cinematic
When Bontrager reached out to use several months ago about an exclusive opportunity to help them tell the launch story of two new tires, we jumped at the opportunity. Like any good mountain biker, we absolutely love fresh tires and when a new tread pattern or compound comes out, it’s almost like a challenge we have to accept. Engineers, much like mountain bikers enjoy a good challenge and the mad scientists at Bontrager’s tire department have been working hard on new recipes, compound application and tread patterns. Today they are launching several new tires and treads, which you can see below, but we’ll be focusing on the SE5 and SE6 as they’re right in our wheelhouse, no pun intended.
The SE line is sort of like Bontrager’s enduro line, you could even say it’s like a super enduro category tire designed for aggressive riders in the 140-160ish-mm range. They’re stout and offer protection against impact without being overly stiff like their G series (Gravity) tires. Construction on both the SE5 and SE6 utilizes Bontrager’s Core Strength casing, which is made of lightweight nylon inserts for sidewall support and protection. There’s a reinforced chafer for added bead protection as well.
Both traction and rolling speed are improved thanks to Bontrager making some moves internally that will yield more control and customization on their own tires. Their TM-Grip grip compound is a soft-dual ply rubber system with a firmer base across all knobs and softer, high grip rubber on top. The 120 TPI construction works with the soft rubber to give great feel and predictability. The new TM-Grip compound is also claimed to roll noticeably faster than the original SE5 while the updated casing also adds 15% increase in protection from punctures.
What users may appreciate most about the updated Bontrager SE5 however is the new knob design. Bontrager eliminated the “float zone” or channel found in the gap between the center knobs and the transition knobs. The tires are now designed to offer a much more predictable feel and give traction as the tire transitions from center to shoulder. A critique many riders had with the SE5 and similar tires, like the Maxxis Minion DHF.
Next up the SE6 is Bontrager’s entry to the most aggressive trail tire category. It’s certainly a monster of a tire. It has plenty of knobs all over for predictable traction no matter which way you’re leaning the bike. We interviewed Bontrager engineers about the tire and it’s similarities to others we’ve seen, and they address that in our interview below. To paraphrase, Bontrager knows that there are popular tires out there that offer desirable traits, and they tested and studied them before making what they thought would be a super aggressive tire for biting traction in any terrain or condition. After just a few months on the tire, we’re pretty impressed with the traction on both sets we’ve been riding, and will report back on our long term reviews coming soon.
One our testers had a few rides on the new SE5 and SE6 tires we reached out to Bontrager with some questions for their engineering team and here’s what they had to say.
Director of Wheels and Tires – Bontrager
TLW: What was the big reason you sought to update the SE5 tread pattern and what were the gains you wanted?
GW: We wanted to accomplish two things with the new tread design. Update the look and add more knob in the transition of the tire to make transitioning from center to shoulder knobs feel more consistent and have less of a dead spot.
TLW: You mentioned that Bontrager made some changes to the new tires beyond just the tread patterns. Can you tell us about the compound, casing construction and facility changes that are helped make your new tires?
GW: For the compound we went from a dual compound that has a harder center and softer shoulder to a dual compound that has the same soft compound across the surface of each knob with a harder compound underneath. This allows the tire to have consistent grip no matter what nob you are on while the harder base compound provides better support for the knobs to reduce squirm on harder surfaces.
The construction went from 60TPI single ply tread overlap with a 3-piece bead to bead puncture protection insert to a 120TPI single ply tread overlap with a bead-to-bead puncture protection insert and additional sidewall protection inserts. The new construction gives us better puncture protection in both the tread and sidewall while keeping the weight and stiffness characteristics similar.
Here’s a handy chart comparing the 2.
TLW: What’s the new compound all about?
GW: (From above) TM Grip is a proprietary dual compound that has a soft (50a) compound across the surface of each knob with a harder compound (70a) underneath. This gives consistent grip across every part of the tread while the harder base compound built into each knob provides better support, reducing squirm on harder surfaces and through hard corners.
TLW: What will a rider notice most if they rode an SE5 last year and hopped on a new one?
GW: A more consistently cornering tire that corners well no matter how hard you push it. The center and side treads work together to get rid of that noticeable transition from center to side tread as you lean the tire over – More consistent through all corners and angles.
The tire also grips better when braking due to the softer surface compound on the center of the tire and the larger biting edges on every other center lug.
TLW: What were important factors when picking the stickiness, or rebound properties of the rubber compounds on these tires? In terms of your team athletes and designers, what’s too soft and what’s too hard? And how did you make that decision.
GW: Ultimately, we chose the surface compound based on our experience with and the performance of this compound in shoulder knobs on other tires. It has a great balance of grip and durability required for a heavy-duty trail tire.
TLW: SE6 is a totally new tread and certainly has some visual queues from other tires on the market. When brands design new tires, are similarities inevitable because there’s only so many ways rubber knobs can be arranged on a tire? Or are there conscious decisions to take things that work and try to improve on them?
GW: Similarities are inevitable when designing tires for certain segments. Especially tires with taller knobs where the knobs have a greater influence on the performance of the tire. For the SE6 tread pattern we did two things to help us zero in on the final tread design. The first was to ride test competitor tires in the segment. This allowed us to identify characteristics that work and we like and those that don’t perform as well in the various tread designs for a given condition.
We then did footprint mapping of all these tires at various lean angles. This allowed us to quantify land/sea ratio of the tread patterns as well as characterize knob pressures at a certain loads and angles. We could then take this data and combine it with our ride test experience to target a certain land to sea ratio and knob design on the tread design. We ultimately settled on a land/sea ratio between the Assegai and the Magic Mary because we felt this would be the sweet spot to allow space between the knobs to allow them to punch through softer conditions while also having enough knob length for decent biting edges.
TLW: Obviously grip and traction come with a trade off, usually in the form of weight and rolling resistance. Did you conduct any tests on rolling resistance between SE5 and SE6? What sort of difference can riders expect?
GW: We tested the new SE5 against the older SE5, and we did get a solid improvement in rolling efficiency there. We didn’t do any formal lab testing of directly comparing the SE5 and SE6 though. That said real world ride testing feedback did indicate the new SE5 felt a decent amount faster than the SE6 though.
TLW: Is there a place or condition where an SE5 front and rear would make more sense than an SE6/SE5 combo or SE6 front and rear?
GW: I like the SE5 front/rear for drier conditions. When things get a little looser it’s nice to have the SE6 up front to bite through and give you improved steering grip. The SE6 front and rear is ideal when things are sloppy.
TLW: Will we see these tread patterns in the G-series of tires?
GW: We are currently working on taking what we have learned with these tires and applying updates to our G-Series tires.
TLW: What did you notice first when you started riding these tires?
- SE5: Wow, the dead spot in the tread is gone. Consistent traction when leaning the tire over all the way through the transition zone.
- SE6: This thing is an awesome front tire.
TLW: Which tire is your favorite in the Bontrager line up and why?
GW: I’d say my favorite combo is the SE6 Front/SE5 Rear. Just a lot of confidence in this setup since the rear breaks traction slightly earlier than the front in corners allowing you to push without fear of losing the front.
TLW: What is your preferred tire set up and what pressures do you run?
GW: Depends –
- Midwest trail on a Top Fuel: XR4 2.4 Front/XR3 2.4 Rear with 24/26 PSI on 29mm inner width rims
- Western trail on a Slash: SE6 Front/Rear with 23/25 PSI on 29mm inner width rims
(I’m 6’0” 180lbs)
TLW: Were you involved with the testing and development process of the tires? If so, what was that like and how many revisions or test samples did you go through to get here?
GW: I was involved in the testing and development of the tires. It was a great experience. We did two competitor ride tests to dial in the direction; one at South Mountain in Phoenix and one in Marquette, MI. Once we got the validation tires we did a series of lab tests as well as a test ride to confirm we hit our mark.
Fortunately, we hit our mark for both, so we got to move these to production, and now get to get them out in the real world relatively quickly. And we hope everyone else is as pleased as we are.