Bike Check: Charles Murray's Pivot Firebird 29

 LoNgEr lOwAr sLaCkRr

 well all my bikes has been size M and my first "new geo" didn't fit me very well so I has to run with a size M (which is pretty much a L in the previous geometry) but with the shorter stem that I could find of 32mm, and still like my previous M with a 65 stem....these numbers just to equal the reach of my actual model.

 I'd be willing to bet most 6ft tall dudes aren't quite 6ft tall, but it's just a hunch.

 @Bro-LanDog: I’m 5-11 now. Once was 6’ even!

 @scotttherider: It's funny, because my height really it depends where I'm at. Normally, I'm 5'10", but in tinderland you best believe I'm 6'0" on the dot.

 @Bro-LanDog: I'm 3mm under 6ft. It bothers me way more than it should. I feel a deep shame ever time I claim to be 6ft.

 @subwaypanda: 3mm?
Do you mean 0¹/8" inches?

 @nozes: I prefer to give my height as 1825.88mm, makes me sound bigger.

 @Bro-LanDog: skinny mirrors conspiracy theory

 He prefers the Medium frame because the bike has ridiculously short chainstays (429mm). With the longer reach of the Large the bike would just be unbalanced. Really pretty obvious!

 @phutphutend: This - spot on. Longer reach must be matched to longer chainstays to keep your weight centered between the wheels - this is what allows you to weight the front of a longer bike properly I'm sure.

 @phutphutend:
See plenty of people on an XL of this bike weighting forward riding exceedingly quick.

If all bikes had long chainstays the world would be a bit boring

 @phutphutend: I tested the large version a while ago and it felt pretty spot on. I guess it's a matter of personal preferences and riding position. I always have problems getting enough weight on the back wheel with all my latest bikes because the chainstays are getting longer and longer. Now with my newest bike I am riding a xl frame to be in a comfortable position between the wheels with my 6ft hight.
However for most riders I guess the increasing chainstays allowing them to ride longer bikes.
So I am actually totally agreeing with you that frame size is not a matter of reach or front center only but always a question of balance between front and back length.

 Rude was running similar set up when he was winning every EWS consecutively...

 @Bro-LanDog: I work part time at a bike shop, and there are plenty of dudes who come in and are 6' tall, give or take 6". Generally men who are clearly under 5-10, say they are 5-10, and those that are 5-10ish say they are 6'. Don't even get me started asking weight for suspension set up!

 @Bro-LanDog: because they hunch...

 @stunnanumma1: me being an inch shorter stems from broken bones and narrowing of joints etc...

 @PauRexs: Rude won all the races he attended on the new SB-150. It's almost like he's a good rider or something...

 @mollow: he was ln a medium 27,5 with 65mm stem for some seasons before moving to L.. and it took him some time to dominate again...

 @subwaypanda: I like to say my wingpspan is 175mm. Makes me sound tall! and here in the USA, I like to tell people I am 170mm tall, makes me sound taller... because 5'7" is SHORT!!!

 @HendersonMike: you’re right, 17cm is short.

 @ddmonkey:

Spoken like someone who has never ridden this bike! it rips. weight distribution on a Large (or even XL) is not an issue...

 @Richt2000: No I've not ridden a Pivot Firebird (I'd like too!) but I have ridden XL enduro bikes with 430mm chainstays and XL enduro bikes with 450mm and I know which I prefer and feel is faster

Riding style, personal preference, whether you are riding for fun or racing, 2cm on the back is not the end of the world either way but I think if you are racing it has a noticable effect. I find my current bike with 450m CS much easier corner at speed. Its not the only factor of course so you can't take it isolation.

Interesting that in the bike check today on PB it says Brook M is running 450 chainstays on his Summum, and he is 5' 9". Sure he's not setting his bike up to do skids and wheelies in the bike park..

 @tobiusmaximum: hahha!! You got me.

 That would be interesting. Let's make it easy, top 20 WC and top 20 EWS riders. Height, reach and stem lenght (stack too maybe). Include the top women too.

 It wouldn't be reprensentative because a lot of pro rider tend to be conservative in their setup. A lot of the time, their skillset let them go away with sub-par setup, something that I, with my mediocre skills and fitness, can't do. I need all the help that I can get to ride the gnarly that I try to ride.

 Medium firebird has a 45.5 cm reach.

 @ORTOGONAL555: definitely stack, also hta, spacers, bar rise, bar roll, bar shape... Am I asking too much? You really do need all this info to compare apples to apples though

 I was just searching for this and could not find a good sample of stem length and stack other than a few youtubers.

 @dagen123: jeeze I wish more people admitted this. Pros can ride more aggressive set ups because they're just better than most riders. Most of us could get on Gwin's DH bike & ride it down the mountain, but I bet it would suck.

 Long reach, relative to size of course, is the traction control of mtbing. Yeah, faster and more in control for most, but the fastest and most controlled riders go without. Fair enough if you want it and it makes you better/faster.

Rally cars don’t have traction control either.

 @dagen123: yes this is true for some racers. However, I thought of this as descriptive info, not as normative. I would't base my choices on this. It would be mostly for fun/entertainment i guess.

 @phalley: all this info would be cool to have, but it might prove hard to collect properly. Actual stack could be easier to obtain (bar height from ground minus bb Height).

 @dagen123: conservative yes, but not “sub-par”. When their whole livelihood rides (pun intended) on them doing well they will definitely set up their bikes perfectly. The key point is that “perfect” set up for a racer is way different to Joe Average. Perfect example is like Gwin’s unforgiving suspension set up... he actively wants this for his speed, whereas I would die. So his set up is definitely sub-par for me, but not for him.

 @dubod22: sounds good , but let's hear it from the horse's mouth. Why Mr. Murray are you on a medium?? What is it that you "prefer"?? As seen as your a pro racer, speed surely precedes feelings??

 The Front Centre:Rear Centre ratio would be cool as it is independent of rider height etc.., I did this for all the winningest bikes in DH history --> its gone from 1.5-1.7 in 2000-2010 period to 1.7-2.0 in 2010-2020 period (AG's YT pushed ratio up to 2) I guess bikes of got longer front centre's but the rear centre has stayed constant. Personally, based on my bikes, I think you need a FC:RC of 1.7 for perfect balance (incidentally its ca. Sam Hills 2007 Iron Horse Sunday ratio ( 1.68 ) and current NP ratio (1.73)).

 @dmitri124: I think manufacturers will dig a bit deeper on this matter in the upcoming years. Dh bikes have longer rear ends than a few tears back (these are the bike I know better), but the increase has not been proportional as can be seen by the ratios you calculated. Big bikes need longer chainstays. Front to rear ratio should stay consistent between sizes too.

 I did this based on the last year worth of EWS bike checks. I’ll post it in the forums later today.

 @Auto-XFil: nice. Any plans about dh bikes?

 @ORTOGONAL555:

www.pinkbike.com/forum/listcomments/?threadid=224438

Nope, I didn't do it for DH. In general they are much shorter, for the few I eyeballed. Maybe I'll put a spreadsheet together if lots of people like the Enduro data.

My current thinking - and I could be wrong - is that for a rider really pinning it, a little bit shorter bike will let them pump and work the bike over terrain with more force. A longer front end will allow higher cornering speeds, IF the rear end is also lengthened, at the expense of pumping and backsiding power. An amateur or lower-end EWS rider who is in "survival more" a little more than the very top-level riders will likely be faster on a bike that's a bit longer, since they are going to want to just hold on and recover sometimes, vs being super active and aggressive. The top EWS riders now ride like DH riders, where they are looking for every tenth of a second and going full gas.

I'd also note that most of the people downsizing are on short-chainstay bikes, like the Pivot in this post, and the SB150 under RR.

So, two aspects: front/rear balance needs to be maintained for max speed (although short chainstays and long front centers can be fun, I don't think they are fast.) This is front-center, NOT reach, so head tube angle plays into this (considerably).

Secondly, the more aggressive and active your riding style, the more you'll likely benefit from a little bit shorter reach. The more you want to be able to hold on and go fast and recover a bit, the better a longer reach will work. This means that reach choice will depend on rider preference, style, course type and conditions, etc. And that XC bikes will keep getting longer, with shorter stems, to let riders recover on the descents with less energy.

 Yep. And now we realize that all this reacher/slacker/longer trend in enduro bikes has no sense in enduro racing...

 @ORTOGONAL555: I agree, bikefit and bike balance will be a key improvement in matching bikes to consumers in the future. As more people buy direct, looking at size S,M,L,XL does nothing to help you understand whether the bike will fit and how it will ride... I pasted my historic "winningest" bikes of DH history analysis into @Auto-XFil thread below plus some anecdotal ramblings on bike fit

www.pinkbike.com/forum/listcomments/?threadid=224438

 @Auto-XFil: thanks for your insight! Can you elaborate a bit more on your 4th paragraph and how the head angle plays into it?

 @jpat22: You can extend the front-center of a bike with head tube angle, reach, or both. Slacker head tubes bring stability because of the change in trail, but they also make for a more stable bike due to a longer wheelbase, just like reach does.

In other words, reach does NOT make for a more stable bike. Wheelbase does. Reach is one way to extend the wheelbase, the other two are head angle (and fork length) and chainstay length. All have their own tradeoffs. I would highly encourage people to try a very slack head tube angle, and long chainstays, but be cautious about going nuts with a longer reach, for all the reasons mentioned above.

 Pretty sure A lot of people use these kind of soft bladders (like a camelbak) that are roughly the size of a small bottle they can be stashed in a jersey pocket/enduro bibs pocket.
Although I have been wondering how they manage with what's probably not that much water, seeing as I'll happily down a tall bottle in an hour if it's warm and I'm pedalling a lot

 Most Pivot riders tuck a water bottle in their pants waistband or put it in a bib.

 @dcrad69: is that not a terrible solution?

 They get to go back to the pits and have places to refill after every stage so it’sa drink for after the climb. Ews has moved away from its origins as a self sufficient big day out

 Whats holding me back is the ridiculous high price over here in europe... Plus the whaterbottle thing

 @CM999: was unaware of this. Yeah most of my hour or 2 hr rides don't have the luxury of pits being provided between the downs.

 @Artikay13: If i was doing a 10km run (training or race) i don't need to take on water.

Yet if i do a 7km (shortest loop at my nearest trails) MTB ride, i feel like i need water (albeit only a small water bottle).

Anyone experience similiar or have any theories? Will accept science or 'science' for answers.

 I've given up on the bottle for enduro racing or enduro-style trail riding. Bladders are so much easier to drink from, carry better on the body than a bottle, don't ever fall off, and I need a pack for tools and food anyway. For casual rides where I don't feel like cleaning a bladder, I use a hip pack that carries a bottle. If my bike had a cage, I'd run a tool wrap where the bottle normally goes.

 @DidNotSendIt: you never stop when running so you don't really think about it. Also biking is faster so the wind dries your mouth more.

 @DidNotSendIt: kinda. I can go wander around town on my bike for an hour or two and jump stuff and not feel the need to drink because I won't bring my hydration pack with me, but if I go out for an actual ride of the same duration and have it I get a lot more thirsty, I figure just because it's there?

 there's bottle mounts under the downtube. I've ridden double black diamonds with it there and never had any issues other than the bottle popping out of the cage when I used a cheap cage with a cheap bottle. I do find it a little annoying that the bottle gets dirty. I don't race, but I use a fanny pack to carry a bottle and a snack and a minimal tool kit.

 @mollow: Think there might something to that. Definitely a case of dry mouth rather than actual dehydration.

Although it was using a bladder in my pack snowboarding where i realised the difference hydration makes. I never used to notice feeling thirsty when i was snowboarding, so generally only had a drink when i stopped for lunch etc.

However, i found that sipping regularly from a water bladder throughout the day (making a habit of sipping on chairlifts etc so you do it automatically) made a HUGE difference to fatigue levels by the end of the day. Muscles still got tired, but i felt fresher and much more alert by the end of the day - when energy, enthusiasm and concentration would otherwise be quite low.

Which is why i'll take a water bladder for any MTB rides 10km+ now. I feel an added safety in keeping alertness and concentration levels up.

 @DidNotSendIt: interesting about the ski. I admit I never hydrate when skiing but I'm sure it would definitely help. Maybe the beer for lunch instead of water is why I always lose my motivation and energy after the break lol. Will try to carry a soft bottle this winter.

 @BenPea: it’s not that bad, I have this bike and racing it with this solution is perfectly fine.

 @Artikay13: they also have aid stations where they can refill periodically

 I just tuck a water bottle into the back of my shorts! Works well, just descend with it mostly empty.

 That’s good to know. Otherwise I would have been even more impressed by his results. I tried those Goodyear tires, yes, they roll rather well, but entering a corner on those in any less than ideal conditions - scary.

 That’s cheating. If your sponsored by a brand then you should be reaching on that brands kit otherwise it misleading at best

 @FuzzyL: yep pretty much the same for me, compared to Maxxis the cornering isn't as reliable. I'll use them this summer at the bike park but I can't use them in winter, not enough tread on them

 Habitual line stepper

 \Who is charlie murphy

 "F yo couch!" Sorry, had to.

 Also glad to see no "Bell Curve" references either

 You can buy a new couch...what am I gonna do about my legs?

 @bman33: love these episodes 3

 @hamncheez: Sam Harris fans know all about this lol

 Sounds like you're basing that theory purely off how pinkbike reviews/commenters say a bike should be designed. If you ask these guys why you will find it's to do with being able to throw the bike around while fatigued.

 Ha ha.
I don’t think people have struggled on bikes with shorter chainstays. Look at mondraker, santa cruz, evil, commencal riders

 @Daaaaaaaan: but doesn't a less stable bike cause more fatigue to start?

 I agree. It's all about weight distribution. Making the front centre longer (i.e. size large) but keeping the CS the same will result in a rearwards weight distribution, making it harder to weight the front tyre.
If you make the CS and front centre longer together then you can keep the weight distribution the same.

The clue here is that he's using a really long stem, which means that he's finding benefits in applying a more forwards weight distribution. I wonder how he would feel about using a longer CS and larger frame if the parts were available for him to test?

 @rojo-1:
He’s using a long stem because the frame is not long enough. I think you’re over keyboard warrioring this. Lots of 27.5 die hards size down on 29 bikes.

 @Richt2000: I don't know the answer, that's just my theory.

He has the option of using a large frame, so the question is, why does he prefer a medium frame, and long stem compared to a large frame and a normal length stem?

P.S. I massively prefer to downsize on bikes, however I am not a racer.

 @rojo-1: I prefer the medium because when you get tired on a race stage it’s a bit easier to control and manoeuvre.

 Man, upsizing frames and going from a 70mm to a 35mm stem was one of the best things I ever did. It's awesome being able to weight the front of the bike without feeling like your face is in front of the tire.

 Burn the witch!

 Earth

 ex3s are brilliant for me

 Also Uranus. Uranus can take a lot of abuse.

 @bishopsmike: I've been to Uranus, the rim I saw was pretty battered.

 I think he’s got a lot of leeway to setup his bike how he likes. If sponsors were running the show, Pivot would probably tell him to ride the large or else Pinkbike readers/customers might get the idea that the new crop of bikes are too long and modern geo is not actually beneficial. If the wheel and tire sponsors were running the show, they’d probably tell him to not run cushcore or at least not talk about it in a bike check as Pinkbike readers/customers might get the idea that the stock rim and tire setup isn’t strong or supportive enough.

I agree privateer bike checks are always the coolest though.