Ask Pinkbike: Tire Casings, BB Compatibility, and Body Position
Here at Pinkbike we get inundated with all kinds of questions, ranging from the basic "Can I have stickers" to more in-depth, soul searching types of queries like if you should pop the question or what to name your first child. Ask Pinkbike is an occasional column where we'll be hand picking and answering questions that have been keeping readers up at night, although we'll likely steer clear of those last two and keep it more tech oriented.
Casing Conundrum
Question: Pinkbike user ondrugs asked this question in All Mountain, Enduro and Cross-Country forum: Does anyone else have issues with Nobbly Nic tires and pinch flatting? And yes, I'm running them tubeless! I've had it happen about four times now, where the rim punches right through the side wall, just above the bead. It also doesn't seal up because of the position of the hole just above the bead. I've never had this kind of issue before, so I just wanted to see if it's my bad riding or if anyone else has had the same issue. I might try some Purgatorys again.
 | You don't say what casing type you're having issues with, but it's probably safe to assume that you're not using the most robust option. When I'm thinking about new rubber, I consider four factors: width (and volume), tread pattern, weight, and casing type. There are many tires that use the same, or at least very similar, tread pattern, but vary massively when it comes to the other talking points, so it's up to the rider to match those factors up with their needs. Simply put, it sounds like your casing of choice, and possible the tire's width, doesn't match your terrain and riding style. This isn't the tire's fault, of course, as that'd be like a downhiller complaining about a rough ride while racing his cross-country rig in the bike park. My advice: play with air pressures before moving to tires with a sturdier casing. Get yourself a proper tire gauge to be sure that you're not running them too low, and if you find that you need to run more than 30 PSI to keep them from cutting, then get a tire with meatier sidewalls. If you like the Nobby Nic, simply move up in casing strength from whatever it is that you have now. Schwalbe lists the Nic as being available in four different casing options, with the Double Defense being listed as the most robust and the Liteskin being the least, so bump up to the former. Still not enough? Consider something with a Schwalbe's Super Gravity casing instead. - Mike Levy |
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Will an Eagle Drivetrain Work on My Bike?
Question: Pinkbike user @waltonracing asked this question in the Bikes, Parts, and Gear forum: I have a 2016 Yeti 4.5. I want to update to the XX1 Eagle groupset. I have a PF92 bottom bracket now with Race Face Turbine cranks, and according to the SRAM web site it won't fit the PF92. What is everyone doing to make this set up work?
| SRAM's Eagle drivetrain is compatible with PF92 bottom brackets, along with just about every other style of bottom bracket out there - I'm not sure where you saw that it wouldn't work. SRAM does refer to their PF92 bottom bracket as "GXP Pressfit" - perhaps that's what threw you off? It is true that your Race Face bottom bracket won't work with SRAM cranks due to the spindle designs, but that's typically the case with cranks from different companies. It's worth mentioning that Race Face bill their narrow-wide chainrings as being 12-speed compatible, and although the aluminum Turbine cranks weigh approximately 100 grams more than the carbon X01 cranks, running them with the rest of the Eagle drivetrain would be an easy way to reduce the cost of upgrading. - Mike Kazimer |
It shouldn't be too much trouble getting SRAM's Eagle drivetrain to work on a Yeti SB4.5.
Body Position
Question: Pinkbike user @foxprodigy asked this question in the Downhill Forum: Hi all. I'm practicing body position by holding it on a bike at home. The problem is, in 30-60 seconds my quad and knee on my back leg start burning ... So, I can't stay on a bike more than two minutes in a static position. What can I do with this, or it is ok?
| Other comments responding to your question suggested that some strength training may be needed to solve your achy issues, but if you can't hold a track stand in a riding position for a few minutes, I think you have an issue with relaxing and having a comfortable position on the bike, not a strength issue. If your quads and knees are burning, you may be standing or pushing through your toes into the pedals and tensing; the key, on any pedal type, is to be able to relax your leg muscles so the weight of your body drops into your heels - if you can't drop your heels below the height of your pedal axle this could cause problems with balance and keeping your feet on the pedals in rough sections. Without seeing a picture or video, it's hard to make a full analysis, so you could check this yourself first by comparing your position to that of riders in videos or photographs. Secondly, bikejames.com has some great videos and instruction on body position and the trailtips.ca app offers free advice if you use their app and post your videos on their Instagram page. - Paul Aston |
Pro riders on flats are the best to learn from; there is no hiding weaknesses in technique by clipping into the bike. Sam Hill heels down, relaxed, strong, and charging, all at the same time.
Have some unresolved tech questions? Jump in the Pinkbike Forum and we'll look to answer it for next time.
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I want to try the maxxis agressor rear soon.
@ReformedRoadie Normally I would agree but I have yet to have my XR4's fail even during enduro racing (and I am around the 180-190lb mark) so I'll stick with the XR's better traction until I find an issue.
I want to try the Vittoria's but I have read repeatedly, that they are really bad in the wet.
Think I accidentally neg propped you, sorry.
They do have slightly different rubbers (the XR4 is ightly softer) so it grips a touch better especially in the wet. also I forgot to mention that the XR4 is 120tpi so much thinner sidewall and lighter (about 140g per tire) so if I'm not having sidewall issues I may as well save myself some serious rolling weight.
... Well, I trust Magic the card game to continue being a card game.
I initially thought the wobble was because the way the tire was folded in the box and would ride out once on the bike. But no.
If your quads are burning you're knees are bent too much. Try this - off the bike, squat with a deep bend in the knees and see how long you can hold it. Now stand up and squat down to a point just before your knees start to give way (should only be a slight bend to the knees) and hold it; you can hold it MUCH longer. Keep this position on the bike as much as possible (you'll need a deeper hip bend). Your quads will go way longer without burning and you'll have more pop when pumping as well.
The real question is, why would you want to be in a static position on the bike in the first place? Good body position on the bike isn't static. Watch any video of pro riders (hundreds to choose from on PB) and you won't see any of them going down the trail in an attack position frozen like a statue. A good good centered/balanced position is the starting point that you use to work through your full range of motion. Take pumping through rollers for example. As you approach the top of a roller, your arms and legs are bent to suck the bike up underneath you, and then extended as you pump down the back side. Nothing static about that. The more dynamic you are on the bike (pumping, hopping, manualing, bump jumping) the less burn you will feel from trying tense up and hold a static position.
I don't know about where you live, but here in Utah rocks are whats mostly on the menu, destroying both tires and P-Tex
@LaXcarp: I tend to pull hard in the rock gardens (i.e. Spencer Branch) and just jump all but the biggest ones. Slowing down and picking lines would help but thats no fun haha. Its all about speeeeed... I charge into them and find that at 35PSI i save tires, rims and everything. Been on the same Minion DHR since June. I used to run 25psi but the faster I got the worse off my rims/tires were.
Firstly I'm just done with Schwalbe. They're expensive and Ive had more than one tire blow up in the first 3rd of a ride and the ones that do have sidewalls that survive wear down ridiculously fast. Admittedly I'm a big dude who is not light on my bike and my local trails are extremely toothy in places but Spesh, WTB and Maxxis fare way better.
Secondly. I can't run even close to under 30psi. I have to run at least 35 to avoid pinch plats or rolling my bead off the rim. I'm not the only one that runs high psi's. A couple really fast dudes that I ride with run roughly the same. I just can't get my head around people running pressures in the low 20's
On the other hand, if you are riding smooth high speed berm, flow, and jump trails or smooth rolling cross country, then 30+ psi may be the hot ticket.
Body position is about form, balance and core stability. Without all 3 (core stability being the most important) there is no point.
At no point is it about holding the same position for 2 minutes!
Just saying and I am an OK rider.
Damn.
Maximus.. maxxis wtf