We all know, there’s no such factor as a silly query. However there are some questions you may not wish to ask your native store or using buddies. AASQ is our weekly sequence the place we resolve your questions – critical or in any other case. This time we talk about mountain bike tire profiles! Hit the hyperlink on the backside of the put up to submit your individual query.
What tire profile is greatest for cornering, and the way do manufacturers check grip on MTB tires?
Final week, the World’s high mountain bike tire producers joined us to reply your questions on how wheel measurement and tire width have an effect on cornering grip. This week, the identical specialists are again, going deeper into the subtleties of MTB tires that assist us go round corners. Thanks very a lot to Schwalbe, Vittoria, Continental, Maxxis, WTB and Michelin for the detailed explanations!
Folks consult with “rounded” and “squared” tire profiles rather a lot in evaluation articles. My native trails are very pure in character… there are not any berms to talk of. The corners are flat with little to no help. Is certainly one of these tire profiles objectively higher for using flat corners than the opposite? Or, does it merely come down to non-public choice?
Schwalbe: There may be all the time a tangential floor in touch throughout cornering, however the larger the air strain, the extra probably it’s the contact patch (when it comes to size/width) will shift relying on whether or not the tire profile is rounded or squared. That will lead to higher cornering or higher braking/ahead traction.
On the decrease pressures we use for mountain biking, there gained’t be that a lot distinction when it comes to size/width of the contact patch. The distinction in a rounded/squared profile will extra probably lead to a unique feeling in order that it comes down to non-public choice.
Rounded profiles will really feel extra agile. You’ll have to lean the bike extra as you nook to get the facet knobs to grip the bottom and vise versa for the squared profile. Please notice that the broader the inner rim width the extra squared a tire will get.
We at Schwalbe all the time attempt to discover a candy spot in between each extremes, nonetheless so long as you run the proper tire strain each tire may have a roughly sq. contact patch below load.
What can also be necessary for journey feeling is how the a part of the tread sample between the middle space and the facet knobs seems. As you lean the bike, a tire with designative intermediate knobs will make the bike extra predictable as a result of the knobs are distributed uniformly. Some folks like that feeling particularly on exhausting floor. Others like the sensation of tipping over onto the facet (knobs) with a particular “channel”.
Vittoria: In easy phrases, a spherical profile will present an excellent dispersion of tread on a given floor, because the tread is all the time tangent to the bottom. On the different finish of the spectrum, a squarer profile will power the facet knobs into the terrain, offering extra preliminary cornering chunk.
If the tire is just too spherical, there’ll usually not be a agency chunk in mixed-surface cornering. If the tire is just too sq., then the tire will probably wash out on the cornering restrict, because the rider leans previous the sting of the profile.
For the rider that requested the query, I might recommend a combined terrain tire with a impartial profile, and a pronounced facet channel between the middle and facet lugs of the tread. A Vittoria Mazza is an effective instance, because the profile is extra aggressive (sq.) than an XC tire however much less sq. than a mud spike, whereas nonetheless providing a balanced quantity of spacing.
Continental: When you’re using berms, the floor is angled to the wheel and tire. For that reason, elements of the middle studs are additionally engaged and the appliance of power is totally different in comparison with “flat cornering.” This why in berm cornering extra pace could be generated.
In “flat cornering” the angle at which the tire is positioned to the bottom is way steeper, so it’s primarily the outer studs which can be in touch with the floor. For that reason, tires with pronounced and well-supported outer studs are significantly appropriate for flat cornering, as a result of they will higher seize into the floor.
As well as, the transition from the central stud space to the facet stud space ought to be designed harmoniously in order that the transition to the outer studs works easily.
Maxxis: Generally, a rounded profile tire has higher steering stability throughout corning because of the smoother contact footprint change from straight-to-cornering transition. A “squared” profile affords higher right away stability as a consequence of bigger contact footprint, however the transition may not really feel as easy from straight to cornering.
This comes right down to the kind of corners and private using type; in your case a sq. profile would probably work higher.
WTB: This can be a nice query and I believe if we return to the dough (featured in final week’s AASQ) it’ll be somewhat simpler to clarify. If we’re assuming that the entire tires in query had the identical width and quantity, then the majority of the tire’s profile could be formed by the tread design – significantly the facet knobs.
Because the facet knobs get larger, they’ll create a flatter profile. As they get smaller, the profile shall be extra rounded. When tires have a flatter profile, it means you don’t should lean the bike over very far earlier than the facet knobs begin biting into the filth. Massive facet knobs imply large cornering traction.
When tires have a extra rounded profile, you’ll typically get constant contact with the bottom whatever the angle you’re leaning at. This doesn’t imply constant grip although as a result of the extra you lean over, the extra the tire desires to slip out and the smaller knobs simply gained’t have the identical chunk as their bigger counterparts.
Above you’ll see imprints from a spread of WTB tires. Every tire was pressed into the dough, then leaned over to 45 levels. As you progress from left to proper, the profiles get flatter, and you may clearly see how this adjustments the footprint left by every tire. The flatter the profile, the larger the facet knobs, the extra chunk as you lean over.
So, again to the unique query: It’s really fairly a tough one to reply as a result of there are quite a few elements that affect which tire it’s best to select. I might really place tire profile extra within the choice class.
As a rule of thumb, I’d favor a barely rounder profile on exhausting pack or “loose-over-hard” terrain to maximise contact, and a flatter profile when the bottom is softer to maximise chunk.
Michelin: Based mostly on my expertise with riders in my MTB profession, “rounded” and “squared” tire profiles are a matter of non-public choice. Some Michelin riders favor a secure, extra squared tire, whereas others favor a extra reactive, rounded tire.
Enduro riders favor extra pure trails and a squared profile for stability, whereas DH riders favor rounded tires for his or her reactivity and ease of balancing from left to proper. For instance, Adrien Dailly prefers the Michelin Wild Enduro tires as a result of they’re extra secure and predictable, whereas Sam Hill prefers the Michelin DH22 tires for nimble dealing with.
When you’re on flat corners, the predictability of dropping grip is totally different between each squared and rounded profile tires. When you’re on the restrict of the grip on flat corners, the squared tires shall be much less predictable and supply much less suggestions for lack of grip in comparison with rounded profile tires.
How do tire makers check cornering grip? Do they only give a bunch of protos to their professional riders or have they got some form of goal mechanical manner of testing grip in home?
Schwalbe: We’ve got no laboratory check for cornering grip. It’s virtually inconceivable to check cornering grip in lab circumstances and apply any findings to the actual world. In mountain biking, there are such a lot of totally different circumstances and surfaces that discipline assessments are essentially the most applicable.
We check our tires with each professional riders and passion riders to get a holistic impression. We often do blind assessments in order that the riders don’t know what’s new or totally different. Moreover our product administration workforce at Schwalbe is basically hooked on biking. We check the tires ourselves at our native trails or go to particular spots. That is very revealing as a result of we alter wheels in group rides commonly and evaluate tires one to 1.
Vittoria: At Vittoria, we have now a devoted testing facility that simulates numerous floor circumstances, in addition to climate circumstances, throughout excessive temperature ranges.
As soon as the tire is confirmed within the lab, it’s discipline examined by a big roster of athletes in any respect ranges, from the World Cup and Grand Excursions, to native membership groups. No Vittoria tire is launched with out each knowledge units, to validate the purpose of the challenge.
By the point we launch a brand new tire, it has already confirmed itself in competitors. For instance, the Vittoria Barzo gained the UCI World Championships in 2015, the 12 months it was launched.
Continental: At Continental, we consider cornering grip utilizing two strategies. Methodology primary is the lab check, the place we measure the grip of a compound together with a tread sample on machines to judge the power of friction that the tire generates on a particular textured floor in numerous circumstances.
This provides us the chance to judge the grip primarily based on measured outcomes and numbers – but it surely typically doesn’t inform the entire fact. A serious half is the out of doors testing. Right here we consider the tire’s efficiency utilizing athletes and ambassadors all around the world in as many circumstances and terrains as potential. Getting lots of suggestions can then assist us design the tire to carry out greatest for its supposed floor, situation and using utilization.
Maxxis: There are a number of issues to contemplate when an engineer designs a tire for cornering grip. Pc simulation may help examine the footprint form and phone strain distribution at totally different lean angles.
Some lab gear may also measure the lateral power at totally different lean angles. The lateral power is effectively associated to the cornering grip. Nevertheless, brief and long run discipline assessments with our athletes are all the time essential to verify the cornering efficiency because of the actual world path/highway circumstances.
WTB: There are various variables which can be continuously altering as you journey down a path. Subsequently, it’s tough to find out and assign an general grip worth for any tire. We definitely measure the durometer (softness) and hysteresis (rebound) of our compounds, which gives quantitative values for a way a lot traction a sure compound will present in numerous circumstances, temperatures, and many others.
Nevertheless, none of that replaces real-world testing. It merely dietary supplements it. We imagine each compound, casing, puncture safety and general tire requires in depth real-world testing to actually decide how a tire performs.
All WTB merchandise are subjected to in depth durations of testing earlier than we could be sure that we’ve created the perfect product potential. We be sure our tires are examined throughout all forms of terrain, in all climate circumstances, and by a variety of riders too. The professionals are definitely a vital a part of that course of and we’ve had quite a few prototype merchandise on EWS bikes through the years with out anyone figuring out.
Nevertheless, our check roster is just not restricted solely to professionals as a result of it’s not simply professionals that’ll use them. We be sure to cowl all angles in relation to testing in order that once we lastly launch the product, we could be assured it’ll carry out because it ought to. If our testing duped us and we’re not pleased with the manufacturing tire…we’ll even replace it down the road as a result of if we’re going to promote a product with the WTB identify on it, we wish to be sure it’s the perfect obtainable.
Michelin: Michelin has the distinctive skill to make the most of numerous chemists and engineers to develop particular rubber compounds that attribute to a variety of product functions. Michelin follows particular check strategies to judge cornering grip and comparability of consistency.
Along with goal testing of a rubber compound’s grip, check riders present subjective suggestions to outline the ultimate product. Riders utilizing prototype tires will replicate their check runs to check traction on the similar pace in the identical nook, or to extend the pace on the restrict of traction for each options.
If a rider is growing pace with all the identical settings on their bike, traction has elevated leading to sooner cornering. When testing cornering, the sensation of dropping grip can also be necessary, and it’s invaluable for riders to know the place they’re in comparison with the utmost restrict of traction.
Thanks a lot to the next contributors to this week’s Ask A Silly Query:
- James Heaton, European PR Guru at WTB
- Alexander Hänke, Product Supervisor at Continental Bicycle Tires
- Robert Mennen, Product supervisor at Schwalbe
- Aaron Chamberlain of Maxxis, with enter from their engineering groups within the US and Taiwan
- Vincent Ledieu, Michelin bicycle enterprise section supervisor and race program chief
- Ken Avery, Senior Vice President of Product Growth at Vittoria Tires
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