I love mid-drives, just read any article I’ve ever written and if you don’t come away with anything else, you’ll feel my love for high power mid-drives shine through. By a far margin, I feel like the best mid-drive on the market right now is the BBSHD with the 2500W ludicrous controller is the best deal to be had ($1200 right now at Lunacycle for the Black Friday sale here). Running 2500W of power through a normal bicycle drive train that is designed for 200-350W is going to wear and break things at a frightening rate. This article is about how to keep that from happening and some of the tricks I have learned in the last 5 years that have kept my bikes on the trail and not in the shop.
Lube the crap out of that chain
There are lots of articles that will say that you’re destroying your drivetrain by over lubing it. I call BS on that, as near as I can tell there is nothing to be lost from lubing your chain before every single ride. I buy chain lube in giant containers and then transfer it into the little expensive squeeze bottles by pouring it into a bowl and sucking it up into the tiny squeeze containers. The lube I always buy is Pedro’s Go! lube in the 1-liter containers available here for <$10 (retail is $45). I’ve tried about a dozen different lubes and this is the one that doesn’t build up on the chains and works well in snow and temps below 0 F.
Bring your bike inside if it gets below freezing
Nothing causes a looser chain than one that is wet and gets left out in the freezing cold to freeze. That water will expand and cause the chain to get a lot looser pretty fast as well as create problems with cable brakes freezing and freezing up derailleur wheels. Get 3 boot trays and put them in a row and bring your snowy slushy ebike inside the house when it freezes, or at the very least bring it into the garage. Garages will stay about 10 degrees warmer than the outside, generally.
Replace your chain and cassette at the same time
A worn chain will wear down the cassette at the same rate so the teeth of your cassette will end up matching your stretched chain. When I swap my chain I generally will swap out the cassette at the same time. If you replace the chain and leave an old cassette it might start skipping, especially in the higher gears. I generally don’t replace the cassette until it starts skipping in 2 gears just because I’m
incredibly cheap frugal.
I only buy all steel cassettes, preferably one-piece ones
There are lots of kinds of cassettes, but I’ve found that the cheaper $30ish all-steel cassettes that are all one piece and not individual cogs last the longest. They are also very heavy, but it’s an ebike, so longevity trumps weight every time. I would also steer away from cassettes with aluminum grannies, as they will quickly taco under serious load and you’ll end up with a giant mess of derailleur, spokes, chain and folded over chainring (true story).
Cheaper chains seem to last longer than the pricy ones
This is something that I’ve noticed, if you spring for a $50 fancy chain it will likely stretch and wear out much faster than getting a $10-15 KMC chain. I’m not sure why this is, but my guess is that the cheap chains are designed for kids bikes that are not ridden that much and left to rust in the lawn, so they are built heavier and more durable rather. KMC seems to make the most durable chains, although sometimes I buy cheap SRAM chains as well. Make sure to use the right size chain for your drivetrain, don’t put an 8-speed chain on a 10-speed drivetrain or it won’t shift right. Single-speed chains seem to last much longer than anything else, which all by itself is a good argument for using an IGH on your ebike.
Go narrow\wide on the front chainring
I don’t generally replace the front chairing unless I get broken teeth or when I start getting chain-suck (chain pulls up past the chainstay and gets stuck and you have to force it back out). I prefer using Raceface narrow-wide chainrings or custom alloy chainrings on my mid drives. Both the Luna Eclipse chainrings and the Lekkie both seem extremely durable and long-lasting. I never use a stamped steel chainring on the front chainring, as I’ve found that I often end up with problems with the chain coming off at inopportune times (is there ever really a good time to lose your chain?)
It’s all about the derailleur
Want a drive train that doesn’t suck? Then its really important to get a good derailleur. I’ve tried a bunch of them and the best derailleur I can find is the SRAM X9 hands down. SRAM keeps trying to replace the 10sp X9 with the GX which I’m not crazy about (although it is a lot cheaper). There are other options out there as well, none of which I can really recommend, even more expensive units. As your shifting cable gets looser over time make sure you twist the adjustment to tighten the cable at the shifter if the bike starts slipping into a higher gear. When you are pumping 2500W though the drive unit, you don’t ever want to be shifting.
Don’t shift under load
Nothing will compromise your drivetrain like shifting while under severe loads. Let up on the throttle, shift, and then start pedaling again. Don’t shift while powering up a steep hill on full throttle. That is just dumb and you will break your ebike.
Freehubs die under severe load, it’s just what they do
Another problem you will come across is trashing rear freehubs. Many lightweight freehubs on expensive bikes will have an aluminum freehub body that will not stand up to serious abuse. Eventually, the steel pawls will push into the freehub body and cause the rear wheel to not spin anymore when you pedal or run your mid-drive. If you can’t find a replacement freehub body then the only way to deal with this is to replace the entire rear hub. If you want to keep your rim then you’ll have to relace a rear hub into the wheel. I would do some research and try to find an inexpensive steel freehub body, which will never fail or get something with ratcheting steel pawls like the DT Swiss Big Ride 350 (reviewed here). A ratcheting freehub will not be cheap, but it probably won’t die on you in the woods when you are 6 miles from your car in a foot of snow (true story).
In the immortal words of Amos, Rocinante’s grease monkey,
“You take care of her, she’ll take care of you”