Chain guard for chainline issues?
Posted by MorganMbored@reddit | ebikes | View on Reddit | 6 comments
Has anybody tried to use an independent chain guard like one of these as a guide to correct chainline issues? I have a BBS02 conversion that I’d love to run a smaller chainring on - the 42t offset ring I have on now was too aggressive for the trails in Sequoiah last weekend - but it had alignment issues when I used the stock chainring.
geyorgespelledgeorge@reddit
What issue are you trying to solve? Chainline alignment causes more wear on the drivetrain and isn't usually the reason a chain comes off, chainslap is probably the bigger issue and I recommend a clutched derailleur over this chain guard, also the lekkie 40t has a guard over the sprocket that helps prevent dechaining. Not gonna be a cheap solution though
MorganMbored@reddit (OP)
When I used the stock chainring that came with the motor (no offset) in the lowest couple of gears the chain would pop off the chainring and onto the motor housing. I got a 42T chainring with something like 10mm of offset and that works, but when I took the bike out to do some trails I found that it was geared too high - the bike stalls out on steep grades and it has to be walked to the top of the hill. I’d love to run a smaller chainring, but I don’t think anybody makes an offset chainring smaller than that because of the diameter of the motor. I’m wondering if perhaps a sacrificial guide can be used to keep the chain on the chainring even with no offset.
Forlaferob@reddit
I got the chain guide in the picture and it's good. As good as a front chain guide too.
Flick-tas@reddit
I installed one because my alignment isn't great and I suspected I'd have issues... The chain has never actually come off and I cant see any wear marks on it, I'm not sure it's helped at all..
I mainly ride offroad and do some rough track bush-bashing at times so I bought a fairly sturdy all aluminium one from eBay: (photo from eBay listing)
Flick-tas@reddit
To add, having a closer look it appears it does have some light marks where the chain has contacted it:
InvestigatorSenior@reddit
chainguard will do what the name says - keep chain on the sprocket if aligned correctly. What you're looking for is adding/removing offset. One possibility is to find front chain ring with offset, the other one is to tweak bottom bracket spacers.
It's possible that ring you couldn't fit has a wrong offset value. This is a bit of esoteric topic so I'd recommend to talk to your LBS.