Help-My BBSHD ebike eats chains and breaks gear teeth ~50 mi

idair

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Dec 31, 2016
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I built an electric "Mongoose Paratrooper" folding bicycle to use for transportation and its ability to fold and fit in the back of a small aircraft. It's worked great so far for this purpose, but every 50-100 miles or so the chain starts skipping gears. Usually it starts in the middle gears and higher gears under load (4-5-6), but it has done it on all gears except the lowest one.

When I bring it to a bike shop, they replace the chain and the cassette, and send me on my way. This works great, sets be back $30-40, and I have the problem again a few months later.

What is the proper fix to improve the reliability of the bicycle?

This bicycle is used to get me into town or around the campsite, but not much more.

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Look up user craneplaneguy
He has set ups like yours and may have info.
 
Don't skimp on the chain and cassette quality next time you have to replace them.

Bicycle components are designed to take human power, which is generally limited to under "400W"

Running 1200W+ through these parts will stress them greatly. If you are buying cheap parts, they don't last.

The last one I did, I used the most expensive SRAM chain (Solid Pins, NOT hollow) and Cassette. These generally last 500+ miles.
 
I'll give this a try my Approach was to go into my local bike shop and request the most heavy-duty thing they had. Maybe this is generally not commercially available off-the-shelf
 
I've had really good service (BBS02 only) using three speeds 11-17-28 spaced 8-speed; with this arrangement the "17" is straight and each smaller and larger gear is one click away. Shifts well, inexpensive components and minimal chain wear since it's not operating at impossible angles.
 
Make sure the chain is actually the right length, and not too long. It should have just enough length to be able to shift to the largest rings you use at the same time; if it has a lot of extra it means the derailer can't fully tension it when it's on smaller rings.

also, the derailer itself should have a tension adjustment, usually a third screw (first two being limiting), that will pull the jockeywheel section back, to tighten the chain.
 
Get rid of rear multicogs that use thinner chains and replace with a 3 speed internal hub wheel with a strong single speed chain.
 
My guess is that you ride in too high a gear all the time. This maxes out the stress on your chain on startups, which stretches it right away, then the stretched chain is wearing out your gears. Back when I was young, I pedaled hard enough in high gears to do the same thing, in a summer.

It also hammers your motor and battery into dogshit. Gear down, and don't ride so hard. Ease into that throttle more.

I think you can get "ebike chain" now, though I'm not sure where they sell it. Cheap generic replacement chain is not what you want. Find something better.
 
KMC makes a specific ebike chain, but I haven't used one yet and SRAM has an eMTB specific group (there are some detractors of SRAM on the site, but I've had excellent success with their chains on single speed MTB's for years).
 
Lots of good advice here. One thing that wasn't mentioned is the derailleur quality, tension adjustments and alignment. You'd think the bike shop would already be looking at that, but perhaps not.

A strong internal gear hub would be a good upgrade (as was mentioned), set up with a straight chainline and properly tensioned good quality chain.
 
dogman dan said:
My guess is that you ride in too high a gear all the time. This maxes out the stress on your chain on startups, which stretches it right away, then the stretched chain is wearing out your gears.

I'll second this comment.

Your goal with a mid-drive should be to minimize stress on the motor and chain. This means always starting from a dead stop in the lowest gear, and shifting your way up to high gear.
If you don't want to do a lot of shifting, eliminate some gears as others have suggested.

I recently built a BBSHD fat bike with a Sturmey-Archer 3-speed IGH and I absolutely love that set-up. The gearing isn't quite as wide as a cassette/derailleur would be, so lower top speed but it shifts like a dream, particularly with a gearsensor installed.
 
I second (third?) the keeping the strain down by using correct gearing. I pooched my first chain/cassette combo in a couple hundred miles with my BBS02, the second (identical) set has lasted me over 2,500 miles. It's an 8 speed SRAM cassette, and I use the biggest 6 most of the time under electric power. I live in a very hilly region, and haul everything with my bike, others could probably get by with less gears.

Maybe a reprogram of the controller as well especially if you're using PAS, the stock settings are pretty brutal under certain conditions.
 
If your drive train is always dirty, it will wear down quickly also. I try to clean especially after dirty ride.
 
I would start treating your chains with machine wax.

https://www.grainger.com/product/LP...m/rp/s/is/image/Grainger/4KK73_AS01?$smthumb$

I have a hot plate with an old coffee can. Every 2-3 weeks when my chain starts making noise I do this:

1) Heat up the whole tube of wax in the coffee can
2) dunk the chain with a wire for 10-15 minutes in the can on the hot plate.
3) hang the chain up, let cool for a minute or two
4) wipe excess wax off the chain as it starts to congeal and cool

It won't prevent chain stretch but it will keep your chain from wearing out faster. I usually push about 6 months per chain this way at 100 miles a week.
 
You go with an old Sturmey Archer or new.


teslanv said:
dogman dan said:
My guess is that you ride in too high a gear all the time. This maxes out the stress on your chain on startups, which stretches it right away, then the stretched chain is wearing out your gears.

I'll second this comment.

Your goal with a mid-drive should be to minimize stress on the motor and chain. This means always starting from a dead stop in the lowest gear, and shifting your way up to high gear.
If you don't want to do a lot of shifting, eliminate some gears as others have suggested.

I recently built a BBSHD fat bike with a Sturmey-Archer 3-speed IGH and I absolutely love that set-up. The gearing isn't quite as wide as a cassette/derailleur would be, so lower top speed but it shifts like a dream, particularly with a gearsensor installed.
 
As well as the excellent advice of always starting off in a lower gear, also try pedaling a few turns before applying the power. I always do this, and it's easily achievable by slightly applying the brake cut-off lever, then releasing when you need the power to kick in. Obviously only works if you've got the brake cut-off sensors fitted.

3300 miles+ and only replaced one chain and one cogset in that time. Ok, mines only a BBS02, but it's maxed out on 'Keep Current' and at 50% on 'Start Current'.
 
That looks like my new project right down to the Surly Singulator chain guide/tensioner. The chassis is close to complete and will carry a BBSHD with ERT's Phaserunner/CA3 kit at 52v until Luna begins to sell 72v packs again. By coincidence, I installed and rigged/tuned the cable and thumb shifter just minutes ago.
 
On top of what Dan and others have said, get off the power when shifting gears. Modern derailleurs and sprockets can shift under full power, but it tears them up. You want the chain to be moving with minimal force on it.
 
teslanv said:
New Sturmey Archer 3-speed for Fat Bikes / cruisers.

http://www.sturmey-archer.com/en/products/detail/sx-rk3
I wonder if they made all the gears wider (more surface area on teeth/roots) with the extra space/width in there? That should make them stronger, too (useful for projects like my trike).
 
I don't believe Karl has broken his. Yet....... :lol:


Which argues for high durability and reliability.

It is a heavy bugger and just offhand it feels like it weighs more than the new SA 5-speed in 135mm. The cases are both alloy so the the three gears must be sturdy to be close to the weight of the five in the rotary hub.

BTW, I had to remove the 5-speed due to a chain derailment breaking the rotary shift hook/cable holder. Having the gear change mechanism inside of the frame is great if you are worried about it being hooked by rocks or brush, but it's not so good if the chain can catch the shift mechanism and break it on a simple derail. The SA 3-speeds in both widths as well as the Shimano Nexus use a hollow axle to pass the shift mechanism out to the cable and while it seems vulnerable to brush, it hasn't ever been an issue and it is well clear of the chain.
 
Well, my usage would be to run a motor (and pedals) thru on my SB Cruiser heavy-cargo / dog-hauler bike, so it would be slammed with power enough to launch me from 0-20MPH in about 3 seconds, on a 300lb+ vehicle (sometimes with trailer, too) with 180lb rider and 250-300lbs of dogs (or even more than that cargo).
 
Remember some eBike chains will not run on narrow wide chainwheels. I m not smart enough to sort why but I have been disappointed with Connex chains.
 
Another way to extend the chain life of a BBSHD is to use the largest chainring available to you. However, that makes it doubly important that you shift the thing into appropriate gears. Start in your low gear and work your way up as you gain speed. Climb hills in a low gear.
 
With the BBSHD and a 30T chainring, what size rear would I need for hill climbing (with the SX-RK3)?
 
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