Rocky Mountain Introduces MX Mount for Altitude and Altitude Powerplay
We're excited to introduce the MX Mount for our Altitude and Altitude Powerplay platforms, which allows for a quick and easy conversion to a mixed wheel size setup while maintaining similar geometry to the stock platforms. The MX Mount is available for purchase for $136 USD on www.bikes.com and is compatible with all Altitude Carbon 29" models, and Altitude Powerplay Carbon 29" models.
The MX Mount
Altitude 29
The Altitude combines decades of racing experience with our latest technology innovations that allow you to ride harder and faster than ever before. With the new Altitude MX Mount installed, you’ll be able to use a 27.5” rear wheel to help corner faster, ride more playfully, all while giving you a bit more clearance when you’re behind the saddle on a steep, technical line.
When you install the Altitude MX Mount, you will increase the travel of your Altitude or Altitude Powerplay while also lowering the rate curve. This means you might have to increase shock pressure or go up in spring rate to achieve proper sag and suspension feel.
The Altitude MX Mount is easy to install and maintains similar geometry to the regular Altitude 29. The Altitude MX mount is designed to be compatible with Positions 1-5 of our RIDE-9 adjustment system only. Position 5 is the “Neutral” position, and the bike becomes incrementally slacker and more progressive as you move towards Position 1, the slackest position. Positions 6-9 have less clearance between the back of the seat stay brace and the seat tube and are incompatible with the use of the Altitude MX Mount.
Altitude Powerplay
The Altitude MX Mount is easy to install and maintains similar geometry to the regular Altitude Powerplay. The Altitude MX mount is designed to be compatible with Positions 1-4 of our RIDE-4 adjustment system only. Position 4 is the steepest position, and the bike will become incrementally slacker and more progressive as you move towards Position 1, the slackest position.
 | With the MX Mount, I’m more comfortable on my bike than ever. And because of that I feel like I’m now able to hit my race speed. |
ALN could be seen running a prototype MX Mount during the 2021 Enduro World Series season.
| I like to bring a creative approach to the trails, search for alternate lines, look for things to double up. Ultimately, I like the extra clearance from running my Altitude with mixed wheel sizes. |
Not just limited to the Altitude, the MX Mount is also compatible with its motorized counterpart, the Altitude Powerplay
Thomas Vanderham's custom Altitude with the MX Mount installed
For more information on the MX Mount, visit www.bikes.com/mx-mount
Video by: @scottsecco
Photos by: @Margus
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There's no worries about where to put a water bottle, the seat tube is uninterrupted, it can be single pivot, ABP or 4 bar, you can have a shock with a long shaft length etc.
You can pretty much put a 275 wheel on anything…
Don’t sweat the slight geo changes so much, slap one on, and give it a try.
Was addressing the OP’s comment about mullets. We seem to get fairly caught up in numbers on paper, give stuff a try, see what it’s like, don’t be so concerned with what some article states about optimal seat angles, etc.
Willing to put a 6-pack on the idea that the stated geo for most bikes are very different from reality.
Trying a 275 wheel on your bike?
So you’ll hit a pedal on the ground a touch more often, Jesus.
Who cares, give it a try and see what it’s like, stop worrying so much.
How much have you calculated that a 275 wheel is going to change your bb drop?
If I ballpark some measurements
Totque 275 has a bb drop of 14, 29 is 30
275 wheel dia is 584, 29 is 622
So half of each is 292 and 311
So bb height on a 275 is 292-14=278
Bb height on a 29 is 311-30=281, so the 29 is 3mm higher
SO in theory, if I swap a 275 wheel on to a 29 torque frame, I’m 16mm lower
Add to that that the chainstay is 440 on a 1250 wb, so FC is 64% of overall (med frame dimensions, RC is the same across all sizes, so on a large or XL frame it has less impact)
So like 10.5mm difference overall I think.
I could be wrong, I’m doing this napkin math in my head as I’m typing.
I realize it’s lower, but I’m pretty sure you’ll be fine if you tried it.
slacken the head and seat angle by about 1 degree
lower reach by 10-11mm
drop the BB by about 12-13mm
raise the stack by 7mm
Should technically be similar across any bike, only thing that will change the numbers is depending on the overall height of the tire used. Can mess with this here: madscientistmtb.com/bike-geometry-compare
Could get away with it if your bike has 175mm cranks, and going with 165mms to offset the lower BB. I have 165mm cranks on my bike and it was the best upgrade I've ever done. I had pedal strikes constantly with 175s and I almost never hit them now.
Cool
I don’t think it’s a question of whether or not you could get away with it, cause clearly you can.
My point is, we (me included) stare at numbers and think they’re set in stone. Stop over thinking it, and give it a try, you’re not gonna die.
Some people get real hung up on these things.
Again willing to bet that most of the posted numbers on geo charts are out from what they’re “supposed” to be anyway.
@mammal ease up champ, unless you’re racing at the real sharp end of some race series stop taking it all so serious.
this massive difference you’re thinking of, I’ll bet it’s similar to changing from a worn Dissector, to a new DHR, no one blinks at that.
You made my point clear, when you said you’d done the calculations, so you knew you were right, that it wouldn’t work for you, and your bike (might be true, I can’t tell you for sure)
I’m just saying, the printed numbers have some inaccuracies built into them, so don’t take em as gospel. Dont be so frightened to give something a try, and try to keep an open mind when doing so.
Swapping from a 2.4 DHR, to a 2.4 Dissector has a huge visual difference, and “feels” like it’s a much smaller volume tire. I don’t have a DHR to verify, but I might swing into the local shop and see what it measures out as. I’ll compare it to my really well worn Dissector, but I’m willing to bet a 5mm difference at least, so theres half the bb height difference right there.
I’m not saying you’re wrong, or that your beliefs aren’t valid,
I just think that all of us (me included) have the tendency to dwell on numbers to make valid our beliefs.
Add to that, now I’m making an assumption here, your bike has a flip chip, that you’re prolly riding in low, there’s 8mm of bb height adjustment there, so you have the ability to compensate right at your fingertips
Took actual tire measurements this morning.
The difference between my moderately worn out 29 x 2.4 Dissector, and a new DHF (29x2.5) is 9mm, so 4.5mm effect on height (in theory)
Same difference with a 29x2.4 DHR.
So, based on your comment that 10mm is a significant change, 4.5 should be something to you as well.
@Ryan2949 actual HA change on my bike with a 275 wheel is marginal, .3-.4 of a degree. Prolly well within spec differences of frames and forks, etc.
So again nothing major.
I’m willing to bet, that most wouldn’t be able to differentiate between the geo changes, unsure about the wheel change.
In closing, I believe you can easily put a 275 wheel on the rear of your bike without any sort of adverse handling changes. With so many different tolerance allowances, and bits and pieces going on, I don’t think many of us would notice the geo changes.
I say give it a try if you want, stop worrying about it.
Mostly just illustrating that we make changes without a thought sometimes, and others we believe are going to have drastic effects.
If 2.5mm isn’t a big deal, how much is, you believe 10mm makes a huge difference, so 2.5 should make a moderate difference?
I think we get caught up on the numbers to justify our belief, rather than basing our belief on what we try.
Like a $150 investment on a used 275 wheel is prolly not going to be too big a deal, which you can then go and flip again if you don’t like it.
You just like to spout on about being an authority on things, without your thoughts being challenged.
Cool man, keep being you.
You stated that you hadn’t tried it, that they were just your assumptions.
I provided fairly clear and easy to understand reasoning as to why your original statement might not be valid, and that seems to have rubbed you the wrong way a bit. That’s cool.
I imagine someone along the way told you it wouldn’t work, and you went with it. The. Some clown on the internet challenged that, and you’re re-thinking your position.
You could have just ignored any of my responses, and it prolly would have died, but you’re still here, reading and responding so you’re interested.
Swing by, let’s throw a 275 wheel on her bike, and do some blind testing on trails you’re unfamiliar with, see if it works. It’ll be cool
Not trying to prove anyone wrong, mostly just trying to point out that it’s not going to be that big a deal, and most people make to much fuss about it.
And you’re right, I haven’t tried it, not sure its going to make much difference to me one way or another, but again, giving it a try ain’t gonna hurt.
I’ve got a spare hub lying around, that needs a wheel, maybe I’ll lace up a 275 to give it a go.
What was “bad” about my math or observations?
"mostly just trying to point out that it’s not going to be that big a deal, and most people make to much fuss about it." YES, I know, you've said this 5 or 6 times now. Go try riding a super low BB if you like. I've tried it, explained my findings (which you don't have to agree with). Bikes are fun, but repeating myself isn't, so this is done.
The OP never made mention of what bike they rode, so you just threw uneducated advice out there to voice your opinion.
A stumpy EVO, which is by all rights fairly popular, and seems to be a hit, has a bb height (in medium and low, which is where I’m guessing most have it) of 333, which is 12mm lower than my Sentinel (which was also a fairly popular bike). Gets even lower in slack and low-331.
So I could easily put a 275 wheel on my Sentinel and prolly not have any issue. I still maintain that most could, a quick look at some geo charts puts most bb heights at 340-350, so plenty of room to drop the 10mm by swapping to a 275 wheel to give it a try.
Hell even your Ripmo could swap out to a 275 rear wheel without too much fuss, (cant fix that bent too tube though, just joking)
As you said, bikes are fun, so maybe stop trying to kill people’s buzz! (intentional)
It may be a way to get another season out of the bike... he's growing fast.
I am also looking at the XS altitude for him as the next bike.
Actually, I hope for their sake that their lawyers' retainers are paid up, since they're selling a first-party official modification that can actually cause frame damage in some configurations and the only thing preventing those configurations is "you should've known better".