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Demystifying Mountain Bike Wheels: A Complete Guide

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If you’ve ever stared at your mountain bike wheels and thought “I have no idea what I’m even looking at”, you’re not alone. Wheels can seem complicated at first glance, but have no fear – this guide will break down everything you need to know about mountain bike wheels in simple terms even a newbie can understand.

So buckle in and get ready to actually understand those circle things on your bike. You got this!

Wheel Sizes – It’s All Relative Baby!

Back in the olden days (we’re talking 80’s and 90’s here), 26″ wheels were the only game in town when it came to mountain bikes. But wheel sizes have exploded like my uncle Jerry after Thanksgiving dinner (true story). Now we also have 27.5” (also called 650b) and 29ers.

  • 26 inch – The OG wheel size still found on some dirt jump and pump track bikes. Nostalgic but limited in its capabilities. Can make bikes feel more nimble though!
  • 27.5 inch / 650b – The Goldilocks wheel size – not too big, not too small, but just right! Balances nimble handling and capability. Ideal for many trail and enduro bikes.
  • 29 inch – The new hotness. 29ers absolutely eat up terrain and carry speed like teenager eats pizza (it’s freakish). Ideal for cross-country riding. Can feel sluggish on super tight trails.

To figure out your wheel size, read what’s printed on the rim/tire or just grab a measuring tape! Most frames can only fit one wheel size but some modern trail/enduro frames can run multiple sizes which allows for some tweaking.

Rim Material – Atom Boom!

You have two main options when it comes to rim construction material – aluminum alloy and carbon fiber. Both have their pros and cons:

Aluminum alloy rims are bombproof and cheaper but can dent or go out of true more easily. However, they can often be bent back into shape somewhat if damaged. Ideal for hardcore trail/enduro/downhill use where crashes happen.

Carbon fiber rims are much stiffer, lighter and more precise feeling when cornering hard or sprinting. However they are pricier and while repairable if cracked, a big hit can ruin them completely necessitating replacement. Ideal for cross country/racing applications.

Most modern trail/AM/enduro bikes seem to spec aluminum rims for durability while hardcore XC rigs go carbon for competitive edge. Wheel stiffness and responsiveness ultimately comes down to more than just rim material though – the hub, spokes, etc all play a role too.

Lock In Your Hubs, Lock In Your Love

Making sure your fancy new wheels actually fit on your bike seems obvious but getting the details right matters. Here’s what to pay attention to with hubs:

Axle Size – Needs to match your frame/fork specs. Road and older MTBs use quick release while modern trail/enduro trends towards bolt-on thru axles for stiffness and security. Boost and Super Boost hubs spread things out even more.

Disc Mount – Make sure your new hubs match the disc brake mount on your bike – 6 bolt or Centerlock. Converting is possible but can require new rotors/tools.

Freehub Body – The cassette attaches to this. SRAM = XD, Shimano = MicroSpline or HG. Make sure your new hub matches the cassette/drivetrain components you plan to use!

Engagement – How fast the hub catches and drives the wheel when you start pedaling. Faster is more responsive but pricier. Personal preference!

Getting the above details right means your sweet new hoops will seamless lock into your bike’s Rear Triangle of Love. Hub/axle specs are admittedly kinda confusing but just match what you currently have and you’ll be rolling in no time!

spokes – Bringing People Together

Spokes literally connect the hub to the rim, bringing these two critical components together in wheel harmony. Here’s some spoke science to dropped at your next group ride:

  • J-Bend – Traditional shape, easy to source replacements
  • Straight Pull – Slightly stronger theoretically and easier to replace but less common replacement options
  • Lacing Patterns – 2 cross, 3 cross etc. Stronger with more crossing patterns
  • Bladed Spokes – Look cool but really only useful for aero gains on road bikes

Higher spoke counts are generally stronger which is why lightweight XC race wheels can get away with low counts while trail/AM/Enduro wheels often have 28-32 spokes or more. More spokes equals more redundancy if you taco one on that latest send!

Consider spoke nipples too – aluminum is lighter but brass holds up better to corrosion over long term use. And remember kids – always protect your nipples!

Wrap It Up Already!

Phew, that was a lot of info! The key things to focus on when choosing new mountain bike wheels:

  • Wheel size – match your bike/fork
  • Rim width+material – supports chosen tire size+terrain demands
  • Hub specs – axle, freehub, brake mount compatible with bike
  • Spokes – adequate for riding style

Getting the basics dialed in means you’ll be happily rolling on that shiny new wheelset in no time. Did this help demystify mountain bike wheels for you? Let me know in the comments! Ride on!

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