Nearly every new bike release today includes information about the bottom bracket cups, cable routing, and sometimes the use of a universal derailleur hanger. That’s because a lot of us who have been riding and wrenching on mountain bikes for years harbor strong preferences around those design elements. Some riders wouldn’t touch a bike with a press-fit BB after listening to them creak and crackle for hours, and spending as much time freeing the ones that are seized in place.
Since there are loads of newer riders getting into the sport we wanted to share some of the mechanic-friendly elements that we consider when purchasing a bike. Local bike shops are an invaluable resource for service and information, but if you plan to perform some maintenance yourself it helps to know what you’re signing up for.
The lowest fruit here is how the frame deals with the derailleur cables and brake hose. External routing, as shown on the Deviate Highlander and GT Force pictured above, is the cleanest-looking way to keep everything accessible and ready for service. The ability to remove the rear brake for a full bleed can make a big difference in the bleed quality, though waltzing around the shop with a frame tipped in the air to get bubbles out of the system is also fun. Additionally, having everything on the outside of the frame makes it easy to find and silence rattling cables.
Alternatively, if you prefer the aesthetic of internal cable routing you will still have some choices to make. Frames with internal routing may have what’s called tube-to-tube, or tube-in-tube routing, which means that the cables and hose pass through channels in the frame and reappear like gofer snakes out the other side. This prevents them from rattling around and can make the install process far faster since you don’t have to fish for the end of the cable as it wanders inside the cavernous frame.
The main drawback to a tube-to-tube routing is that it doesn’t leave space to slide the olive and barb on a rear brake hose through. If your brakes use those little bits to attach the hose to the lever you will have to cut off roughly 1cm of hose every time you want to take the rear brake off for any reason, then reinstall a new olive and barb. Eventually the brake hose will become too short and will have to be replaced.
While external routing can simplify maintenance, it’s by no means the superior method. It’s just preference. If you find a frame that fits all the other criteria you’re looking for the cable routing shouldn’t be a deal breaker either way.
The next maintenance consideration for a new frame is the bottom-bracket. A set of external or BSA bearing cups are easy to remove, service, and swap, and if installed correctly they’re silent. Bottom bracket cups or bearings that press directly into the frame can take a little more work to keep quiet. There are thread-fit alternatives to quiet press-fit bottom brackets, but anything that presses into the frame will require some large and often expensive extraction tools. Thankfully the bike industry heard the complaints of home mechanics everywhere, and most bikes come with threaded external bearings today.
Headset bearings function almost identically to those in a BB, though the drawbacks between systems are fewer. Pressed headset cups remain in the frame when the bearings are swapped, making the maintenance process identical to that of headset bearings that slide directly into the frame, and both methods are fairly quiet and simple. Several years ago there were issues with bearings fitting poorly and wearing the inner head tubes of frames, so folks felt that pressed headsets were better because the bearings don’t sit directly on the frame. Those issues seem to have been remedied, for the most part, so the only drawback to one style or the other is that a pressed headset cup requires expensive installation and extraction tools. Since you only need to install the headset cups once this is largely a moot point.
Once you’ve learned to perform most of the maintenance tasks on your bike the pivot bearings will likely start to feel crunchy and beg for replacement. How many different bearing and/or bushing sizes a frame takes and how common the sizes are is another worthwhile consideration. Some frames use a mix of bearings and bushings in the pivots, and while those factors shouldn’t necessarily choose the bike for you it can be good to read some forums and find out what owners have to say about the bike’s bearing and bushing life.
Maybe this should be at the top of this article: mud clearance and overlapping linkage is of utmost importance if you ride mountain bikes in wet conditions. Tight overlapping linkages like that on the Sunn Kern EN pictured above require regular cleaning to keep dirt from building up and causing the carbon fiber tubes to essentially sand one another. The large mud-pocket at the base of the bike’s shock is also worth a close look, as dirt will slowly build up and get packed into the coil. On some bikes, like the Mondraker Foxy, this mud pocket actually feeds trail debris directly into the shock. If you enjoy a good muddy slide and don’t want the frame to suffer for that fun it’s worth considering the crannies that crud can stick to.
While there are several other frame maintenance variables to consider, one final bit we will mention is the derailleur hanger. Loads of bikes are coming with the new SRAM Universal Derailleur Hanger which can easily be found at most shops. It also only costs about $15, so strapping a spare under the saddle is a reasonable move. It was smart of SRAM to design a “universal” component like this, and equally sly for all of us to pack a spare.
Braking and drivetrain components
Some folks say they only want brakes that use DOT-5 fluid, because if it’s good enough for cars and motorcycles then it’s best for their bike. The catch is that DOT fluid is toxic and you don’t want to get it on your skin or paint, while mineral oil is less hazardous to handle. No matter where your feelings lie on this discussion, it’s worth considering. Brake systems that use DOT fluid include those from Hayes, Hope, and SRAM, while brands that use mineral oil include Formula, Magura, Shimano, TRP, and Trickstuff. One benefit of DOT fluid is that you can find it in any auto parts store, whereas top-quality mineral oil will require a trip to the bike shop. These are just a few of the many considerations between different braking systems, which is why we share all of the nuances in our thorough reviews.
Fortunately, drivetrains are all pretty great these days, and there aren’t any real maintenance gains or drawbacks to consider here. If you do build up a bike with a BOX 9-speed or any 10- or 11-speed transmission you’ll want to pack a spare chain in the car or suitcase just in case. As 12-speed systems gain popularity it will become increasingly difficult to find replacement parts for 9-, 10-, and 11-speed systems in small mountain towns while on vacation.
When buying a complete bike, it’s good to check if you can get a direct-mount chainring in the size, color, and roundness you like for the included crank.
Suspension and dropper posts
Apart from the two leading brands, most suspension companies have made it easy to adjust the travel of their forks by dropping the lowers and installing or relocating some spacers. This is another place where designers and product managers heard the requests of customers and created a simple solution. While this may not be a primary concern, it’s a sweet benefit when selling a fork to someone who needs a different travel measurement, or when you want to mount the fork on another bike. Most forks from Fox and RockShox can also be adjusted by swapping the air spring, which requires a little more time and cash investment. Some shock-stroke lengths can also be changed, though it’s a somewhat larger job than that with a fork.
Being able to change fork volume spacers with tools you already own is a fantastic boon for home mechanics. Air spring caps like the one above from an X-Fusion Trace36 allow you to quickly swap spacers with a lockring tool, instead of buying a clunky 32mm socket. This is a favorite feature of home mechanics everywhere, and it would be fantastic if the whole industry moved to this style of air-spring cap.
Dropper posts are exceedingly easy to rebuild and service today, with the Fox Transfer as one exception that has to be sent back to the factory.
With dropper posts growing longer, several companies are also moving to the wider 34.9 option for more robust internals. Trek Bikes’ Ross Rushin explains “we went [with] the wider post diameter on Slash for better strength and durability. The wider diameter better supports the extra length of these long-travel droppers that are so hot right now. That also opened up some extra space in the dropper itself for more robust internals and more oil flow for a faster return speed and easier compression.” Those all sound like positive moves to us.
How the dropper cable end attaches to either a handlebar remote or the base of the post is a variable we regularly scrutinize. If the cable is clamped at the lever you can run it through, set the saddle height, then tighten the cable and cut it all while maintaining light tension on the cable itself. Assuming the housing is already cut to length this method takes less than five minutes for a new post install or cable replacement, and the lever can remain on the bar throughout. Alternatively, if the cable-end is clamped in a knarp at the base of the saddle, you often have to remove the lever and slide the housing through the frame in order to get a precise measurement between the housing and the post-actuator base. Then tighten everything in place and try to guide the housing into the frame without kinking anything. Here most of the bike industry has jumped over to the quick and easy route, with but a few holdouts.
The days of obscure aluminum spokes and nipples that are molded into the rim are largely over, and most wheels now come with relatively standard parts that are easy to find. Even the classic debate of straight-pull versus J-bend spokes goes out the window when you need to replace a spoke before the sun drops behind a mountain. You take the length that can work and straighten or J-bend it to your needs. Most wheels use one of a few different sealed cartridge bearing sizes that are easy to find at any shop and can be replaced campfire side with the right chunk of wood and a hammer. A dwindling number of hubs, like those from Shimano, still use cup-and-cone bearings that are even simpler to service.
Some of the few things left to consider are how the inner rim width relates to your preferred tire size, and which rotor-mount style you prefer. Folks who travel a lot might appreciate the time-saving ease of removing and installing rotors with a cassette lockring tool, while others will prefer the 6-bolt mount for the ability to tighten the bolts with a multi-tool and to steal a bolt and use it elsewhere if necessary. The rotor will work fine with four or five bolts if you need to borrow a few in a pinch, and they fit in many of the holes on your bike.
Now it’s tour turn to share some of your mechanic-minded frame, bike, and component buying considerations. We’ve only scratched the surface here and would love to hear the factors that are important to you as a home or shop mechanic in the comments below.