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  1. #1
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    How much does light xc tire impact race times?

    Just about to do a 4 by 24 hour race with friends (2nd race ever for me), and wondering if switching from my 29" Kenda Nevegals to Small Block 8s will have a big impact. They feel quicker and lighter, but reading such articles as this Lee Likes Bikes might lead you to believe otherwise.

    In a relatively tame race/course (as I think Great Glen is), I believe the SB8s will be much faster (low rolling resistance, lighter) but don't know. I assume the guys winning xc races ride the correct stuff, but don't even know what they ride.

    Question: has anyone ever run heavier vs racylight tires and found significant time differences? Not really looking for weak opinions, but rather someone who tried and has some good data. I'm looking to convince a teammate to ditch his nevegals for something lighter out of the bin.

    Thnx.

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    Re: How much does light xc tire impact race times?

    The difference you are getting with those two besides weight is rolling resistance. A much bigger deal than weight.
    There will be a night a day difference between the SB8 and Crapegal.
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  3. #3
    DLd
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    I dropped a few minutes off a 17 minute (down to 13:15 now) climb when I switched to a new set of carbon wheels with some really light race tires. Nevegals are pretty slow rolling. Are you guys looking to win or just have fun and hang out though? I can see if he doesn't want to lay down the coin for tires he won't use otherwise.

    I have to say I lost a little respect for Lee after reading that article though. He has his little spreadsheets and numbers to make it all seem scientific, but all the numbers he's plugging into them are just assumptions. Cornering twice as fast? Really? What kind of terrain is that on? All flat corners with gravel? I'd give it more creedence if he had just done back to back rides with the different tires and collected actual data instead of all the made-up numbers he had in the article.

    I have to say, any speed gain in cornering or downhills from the tires is really terrain-specific. If it's hard-packed with berms there's not going to be an advantage from big knobbies, same if it's slickrock type conditions. If every corner is a blown-out off-camber mess, well you might need to slow down pretty signifigantly with either. I find even my downhill speeds on XC trails are higher on my light bike with light tires (still RoRo front, RaRa rear, not like furious freds or something like that). I personally don't prefer the SB8's as they don't seem to work well on the loose over hardpack we frequently have here in AZ, but Ikons, Rocket Rons and X-kings are what I see most people sporting at our XC races, which tend to be pretty rocky, sandy, and techy at times (not wet and slippery roots and rocks, that's a whole different beast).

    If he doesn't feel comfortable and is going slow in each corner because he doesn't trust them it might not help. He'll need to ride them before the race to develop confidence in them. There's that point in rider development where maybe you've lost traction and crashed a few times on the tires that came on your bike, so you upgrade to burlier tires and the crashes end up becoming less, but you don't realize the crashes are less because your skills have developed and you could go just as fast on less burly tires if you just gave it a try. In a race a few months ago I was worried about my tires and traction, and I looked at the tires of the guy who won the race, going a lot faster than me even on the downhills, fast guy, and he had some racing slick on the front, like a furious fred, but I don't remember the brand. Technical course with big downhills too. I realized I could have run a racing ralph on the front too and have had more traction than him and a decent amount less weight for the 5000' or so of climbing.
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  4. #4
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    OP, it sounds like you have both sets of tires. Give them both some ride time.

    Bear in mind that it's not all-or-nothing. I've been riding with chunkier tires on the front than the back for ages. A lot of cornering action happens at the front and while I prefer not to skid, the occasional rear wheel skid is recoverable. Meanwhile, on the way up, more of my weight shifts to the back of the bike. Mountain bikes are rear-biased anyway. So I don't think that losses from a front tire with more rolling resistance are as bad as losses from a rear tire with more rolling resistance.

    Personally, I'd go with a tire I was comfortable with and maybe sacrifice a little rolling speed in favor of something a little more forgiving for a 24-hour event. Though, I've never done a team endurance race myself, so I dunno - maybe it's easier to stay sharp in the middle of the night than I think.
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  5. #5
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    How much does light xc tire impact race times?

    Quote Originally Posted by benoksanen View Post
    Just about to do a 4 by 24 hour race with friends (2nd race ever for me), and wondering if switching from my 29" Kenda Nevegals to Small Block 8s will have a big impact. They feel quicker and lighter, but reading such articles as this Lee Likes Bikes might lead you to believe otherwise.

    In a relatively tame race/course (as I think Great Glen is), I believe the SB8s will be much faster (low rolling resistance, lighter) but don't know. I assume the guys winning xc races ride the correct stuff, but don't even know what they ride.

    Question: has anyone ever run heavier vs racylight tires and found significant time differences? Not really looking for weak opinions, but rather someone who tried and has some good data. I'm looking to convince a teammate to ditch his nevegals for something lighter out of the bin.

    Thnx.
    You are always faster on the tire (and other equipment) that gives you the most confidence. You are not very fast if you keep crashing, or need to slow down more to stay on the trail.

    What feels "fast" is not when you actually time/record it. Control and grip can seem slow because you do not have to make as many corrections. I have tested this many times. Not just different tires but also different pressures with the same tires.
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  6. #6
    CB2
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    If it is wet this weekend SB8s are awful in the wet around here.
    I'll be racing Conti Racekings this weekend @ Hodges and next week @ Hampshire 100. They look similar to the SB8s, but hook up in all conditions way better IME (and roll SUPERFAST).


    Good luck Ben!

  7. #7
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    I'll agree with Shiggy in that if you're not confident in your equipment you'll be slower than if you rode the slower/heavier stuff you are confident with.

    This being said, the Nevegal has to be THE slowest rolling tyre I've ever ridden, there are so many other great options out there that offer excellent grip while not rolling like molasses. If you want fast, yet still decent grip I'd venture to something besides the Nevs, but not sure I'd opt for the SB8s unless the course is just hardpack, if there's any loose over, nope. Good fast tyre for the rear could be the SB8 since a little drift isn't bad out back and then something else upfront for good grip.If you can't afford/don't want to spend any more money, then run the Nev on the front, SB8 on the rear.
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    How much does light xc tire impact race times?

    Quote Originally Posted by LyNx View Post
    I'll agree with Shiggy in that if you're not confident in your equipment you'll be slower than if you rode the slower/heavier stuff you are confident with.

    This being said, the Nevegal has to be THE slowest rolling tyre I've ever ridden, there are so many other great options out there that offer excellent grip while not rolling like molasses. If you want fast, yet still decent grip I'd venture to something besides the Nevs, but not sure I'd opt for the SB8s unless the course is just hardpack, if there's any loose over, nope. Good fast tyre for the rear could be the SB8 since a little drift isn't bad out back and then something else upfront for good grip.If you can't afford/don't want to spend any more money, then run the Nev on the front, SB8 on the rear.
    I have ridden much draggier tires, and the Neve has only felt slow on pavement.

    Regardless, rule #1 for races/events: do not use anything new, unfamiliar, or unproven.
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  9. #9
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    Agree that there are tyres with much stickier compounds and that roll slower, but in the 750-850g range the Nev has to be the slowest rolling for the amount of grip it provides. For me with 29ers, the Nev just didn't make the transition from 26" well - used to love the 26" iterations, the 29" always just felt so so to me.
    Quote Originally Posted by shiggy View Post
    I have ridden much draggier tires, and the Neve has only felt slow on pavement.

    Regardless, rule #1 for races/events: do not use anything new, unfamiliar, or unproven.
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  10. #10
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    Nevegals are really really slow. But they corner like crazy.

    If it was me, I'd go for a slightly faster rolling tire than the Nevegal, but not quite SB8 fast.

    What I chose is the Ardent 2.4 front, IKON 2.2 rear combo. That has a nice and sticky, but still ok rolling tire in the front, which inspires cornering confidence. That tire will save your ass. Then the rear is a fast rolling tire with not too much lateral grip. What that means is the back of the bike will lose traction before the front, further inspiring confidence, as that's easier to save than a front washout.

    That sort of combo is available in pretty much any brand (for example, Hans Dampf front, RR rear or Mountain King front, Xking rear or Xking 2.4 front, Race King rear)

    I agree with that article posted in the beginning of the thread. In a 100% singletrack "lap" style sort of race, I take the FR tire all day long. In a race where all you have is straight climbs and straight descents and little cornering (leadville for example) let's go with the XC tire.

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  11. #11
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    I got the opportunity to ride XC with Lee McCormack last year. He didn't climb that good, but he just destroyed on the DH. Holy Crap!!
    He's an excellent instructor and just so enthusiastic about the sport. Great guy.

    His article makes some great points which I agree with. You'll lose a little on the climb but you can gain a lot every corner with a beefier higher volume tire. The only problem with XC mass start racing is that there's always the passing/blocking issue which somewhat negates the advantage of better handling tires. It's always nice to be out front from beginning climb.

    I run Conti Mountain King Front and XKing rear, both 2.2 i think. Run them at 27psi rear, 25 psi front. On our rocky midweek course I'll occasionally feel rim at this pressure.

    Here's some more findings on tire size, pressure, rolling resistance, etc:
    Rolling Resistance | Schwalbe North America
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  12. #12
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    Leeís article raises an interesting point. I donít see a ton of rigor behind his math model (e.g. where did 0.3Gs vs 0.45Gs come from?), but if you take the weight and rolling resistance reduction argument to the extreme and raced MTB on skinny slicks, I donít think youíd make up the speed you lose in the turns by being faster on straights and climbs. So, there seems to be a compromise point somewhere on the matrix of weight, grip and rolling resistance.

    IMO, increasing tire weight slightly to improve grip would be MUCH better than increasing rolling resistance. For example, if you went wider with the same tire to get a little more rubber and knobs onto the dirt even if that means increasing the weight of the tire, thereís likely a net benefit. Some studies even show that wider tires can even decrease RR.

    The reason I think RR is so much more impactful, is because the % difference in rolling resistance between a Nevagal and SB8 (for example) is a lot more than the weight difference as a % of the total bike + rider system. So, also IMO, giving up 200 grams in weight for 20% better cornering is likely worthwhile. I wonder is how compromising RR for better grip would really play out but Iím not ready to go with a downhill tire for XC racing yet!

    Also, some (including Lee) argue that rotating wheel weight is more important than Iíve given it credit for above since itís spinning. I think this argument is 99% bunk. It takes very little energy to spin the wheels themselves up to the typical XC speed of 12mph. Flip you bike over and you can spin the front wheel up to that speed with your little finger. Thatís all the energy we have to work with when we talk about better acceleration by reducing the rotational mass of the wheels. The energy that takes to spin the wheels up is TINY compared to the energy it takes to accelerate my 200lbs of body and bike from 0 to 12mph. This argument is technically correct but practically its negligible. Weight is pretty much weight whether itís on your bike tire or on your spare tire.

    Anyway, I'd love to see someone do a study (Schwalbe?) on how to optimize rolling resistance, grip and weight on a variety of courses!

  13. #13
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    Thanks for all of the feedback - I'm thinking of backing off my original plan a bit and going SB8 in rear, Maxxis Ardent 2.2 in front for a little more traction (it's what I have on hand, seems a bit lighter and less knobby than Nevegal). Will be on site early Friday to give it a test.

    Now for the real question ... should I ride my hardtail or full susp? Just kidding on that last question - I hope to run both and report back.

    Thanks again, and happy riding.
    Ben

  14. #14
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    Quote Originally Posted by shiggy View Post
    You are always faster on the tire (and other equipment) that gives you the most confidence. You are not very fast if you keep crashing, or need to slow down more to stay on the trail.

    What feels "fast" is not when you actually time/record it. Control and grip can seem slow because you do not have to make as many corrections. I have tested this many times. Not just different tires but also different pressures with the same tires.
    This. 100%.

    You will never be able to find good scientific data on something like this because the system of comparing bike rides/bikes/riders/tires/trails/conditions is just too complex and contains too many variables to be able to factor out enough to compare what you want.

    The only thing you can do is time YOURSELF on YOUR trails many times with multiple tires at multiple pressures in similar conditions. What you'll find is that the 200 or so rides you'll have to take to do this successfully will improve your speed much more than switching tires will by itself.
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  15. #15
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    Light? Not a huge affect.
    Rolling Resistance? Big difference.
    Cornering Traction? Probably not much, I would guess I spend about 2% of my race time near traction limit of my tires.
    Durability? Very important.

    All my fastest downhill times are on tires with little rolling resistance, not the grippy high rolling resistance tires. That should say something about efficiency.
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  16. #16
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    Re: How much does light xc tire impact race times?

    I'm no winner or champ but I used to go for the fast rollers with minimal tread because, well, they felt fast! Then I realized that I had to really dial back my descending and cornering to feel confident enough to stay upright on those tires. I didn't do any timing, but I realized that the fast rollers were for the most part less fun to ride. Now I fall into the chunky up front, little faster in the back camp.

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  17. #17
    DLd
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    Well if the question is will the lighter tires have enough grip to make it around the course fast, just look at the tires of the people who end up winning the event or setting the fastest lap. You'll know for sure that they were able to negotiate the same course and conditions faster than you. If they were doing it using tires with less aggressive tread then you know the advantages of more aggressive tread are just in your head.
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  18. #18
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    Quote Originally Posted by DLd View Post
    Well if the question is will the lighter tires have enough grip to make it around the course fast, just look at the tires of the people who end up winning the event or setting the fastest lap. You'll know for sure that they were able to negotiate the same course and conditions faster than you. If they were doing it using tires with less aggressive tread then you know the advantages of more aggressive tread are just in your head.
    That assumes everyone is at the same skill level.

  19. #19
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    Exactly, but some people are just so badass (in their little minds) they have to try to belittle people with lesser skill
    Quote Originally Posted by ewarnerusa View Post
    That assumes everyone is at the same skill level.
    Quote Originally Posted by DLd View Post
    Well if the question is will the lighter tires have enough grip to make it around the course fast, just look at the tires of the people who end up winning the event or setting the fastest lap. You'll know for sure that they were able to negotiate the same course and conditions faster than you. If they were doing it using tires with less aggressive tread then you know the advantages of more aggressive tread are just in your head.
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  20. #20
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  21. #21
    DLd
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    Quote Originally Posted by ewarnerusa View Post
    That assumes everyone is at the same skill level.
    No, actually the opposite. It acknowledges the fact that people are all at different skill levels. In other words, it's not the tires holding you back. Some folks have more experience, some have more time to train, but the fact that it's possible to make it around the track that fast on those less aggressive tires proves they have sufficient grip to do so.
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  22. #22
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    Quote Originally Posted by DLd View Post
    No, actually the opposite. It acknowledges the fact that people are all at different skill levels. In other words, it's not the tires holding you back. Some folks have more experience, some have more time to train, but the fact that it's possible to make it around the track that fast on those less aggressive tires proves they have sufficient grip to do so.
    I interpreted the comment i quoted to suggest that it is a crutch to rely on aggressively treaded tires a means of feeling comfortable for a personal race pace. The justification in that comment was that the fastest people may do it on fast rollers, so anyone should also be able to do their race pace on fast rollers (because as demonstrated by the fastest people, it can be done). I disagree because not everyone feels up to pushing it on low tread tires. I know I don't, I mentioned that in a previous post. We are not all at the same skill level as the people winning.

  23. #23
    DLd
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    Quote Originally Posted by ewarnerusa View Post
    I interpreted it the comment i quoted to suggest that it is a crutch to rely on aggressively treaded tires a means of feeling comfortable for a personal race pace. The justification in that comment was that the fastest people may do it on fast rollers, so anyone should also be able to do their race pace on fast rollers. I disagree because not everyone feels up to pushing it on low tread tires. I know I don't, I mentioned that in a previous post. We are not all at the same skill level as the people winning.
    Exactly. So much of it is mental. We don't have confidence in a tire with less tread, so we go slower, but the race times of the faster guys prove the tire has enough grip. It's our preconception of what the tire is capable of that oftentimes limits our speed.
    "Great things are not accomplished by those who yield to trends and fads and popular opinion."-Jack Kerouac

  24. #24
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    I am by no means a great rider. I spent a 3 week vacation in New-Mexico and Colorado riding on Continental RaceKing Supersonic's ghetto tubeless. Only in dry conditions. Total of about 12 different rides including part of the Colorado trail, Fruita, in Santa Fe, Taos, Buffalo Creek.... the only limiting factor was me, not my tires nor my bike. Some asphalt in there when I climbed to the top of Windsor in Santa Fe. No official downhill runs obviously... But I would not have ridden with these tires in mud, but for everything else, they have been very good.

  25. #25
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    ... just realized the question had to do with racing ...

    I did race a fairly non-technical course with these tires over a few years and again, the tires were definitely not holding me back. The track was really bumpy but those big Race Kings with about 20lbs pressure made climbing faster, I think. Being the only singlespeeder on the course also meant that uphill also means standing and having to go faster than the others... also means that I probably came closer to throwing up more than the others...

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