STLJohn

Hello could someone point me to some guards or a new chainring with guards for an electric recumbent please? It has 38t and 75mm between the 5 holes. This it to prevent the chain from coming off. I posted pics on r/bicyclerepair, won't let me here as a newb.

soyabean

A chainring guard is to prevent your socks and leggings and pretty shoes from scruffing a greasy chain.

If your chain is slipping off, the issue is elsewhere.

Without fixing the issue, the chain will just grind against the plastic chainring guard until it breaks off into pieces like they all do when chains hop off them.

STLJohn

A powerful stroke tilts the chainring a bit. It is a single gear, I think dual chain guards might prevent the chain from jumping off.

soyabean

Nope.

Plastic chainring guards are purely cosmetic.

They aren't steel pulleys to keep a torque driver in place.

That's why most folks don't replace them after they break off.

None of my personal use bikes have chainring guards.

My chains NEVER slip off.

STLJohn

Yeah it's a bit different on a recumbent though, I don't know if you ride. Sunlite makes a good double guard chainring that I would wager would be helpful, except the hole spacing is different.

soyabean

You're missing the point.

No chainring guard is made to keep a chain on it.

You're avoiding the issue completely by ignoring that is causing your chain to slip off.

I know all bikes. I've serviced and sold recumbent bikes too.

Camilo

My recumbent tadpole, when I had one, had exactly the same crank as a mountain bike - I know because I replaced the original road-ish triple with an MTB triple crank to get lower gears. The FD adjustment was exactly the same as any other bike and if done well, prevented chain drops.

Aren't those chain guard things called bash guards and intended to protect the chain ring from damage on MTB trails? Or is that a different thing?

oldschoolbike

75 mm between holes sounds like it might actually be the common 76.4 mm or 130 mm BCD (Bolt Circle Diameter). It's easy to make that measurement error. If you can confirm that it's really 130 BCD (check the fine print on the chainring, it might say), then try Spa Cycles in the UK.

https://spacycles.co.uk/m8b0s210p447...nguard-130-BCD

Cyclocross riders used to run inner and outer metal guards on single rings. It may have been more for bash protection or self-protection when carrying the bike than for chain retention, but it could easily have been for all three AFIK. If chain retention is the only concern, a single speed chain guide, essentially a front derailler with no movement, is an alternative but it won't work if the cranks get rotated backwards accidentally. It only protects the pick-up point.

choddo

If it’s only big pushes then the backpedalling thing shouldn’t be an issue

any reason not to put a narrow-wide chainring on this if it is a standard BCD? E.g. https://www.bikeparts.co.uk/products...-black-130x42t

having said that, most in-regs electric motors don’t produce as much torque as strong cyclists so not sure why this chainring would tilt under load but maybe there’s something about recumbent geometry I don’t understand

jgwilliams

What bike is it? I used to have a recumbent myself until I moved and decided it wasn't really a good location for riding 'bents, but I'd like to see pics when you've got enough posts.

There's a forum at bent rider online that you might find more helpful. Someone there is more likely to have come across your specific problem. They have a specific sub-forum for power-assist bikes.

Chuck M 

I have to agree that the chain coming off has a root cause so a guard is not going to be a fix.

Problem statement: Chain is coming off.

Why 1: Why is the chain coming off? A powerful stroke tilts the chainring a bit.
Why 2: Why does a powerful stroke tilt the chainring?
Why 3:

You should answer why #2 and then keep going until you can't answer why any longer.

oldschoolbike

Maybe the chain comes off because the runs are too long and side-to-side slap is unshipping the chain. That was a constant problem on the only recumbent I ever had any real contact with. If so, OP needs guard rings inside and outside the chain ring as he/she suggests, or chain guides top and bottom. The problem with guides is finding mounting points, hence metal guard rings on the chainring.

oldschoolbike

Jeff Wills

Nope. I’ve worked on recumbent bikes for 40+ years, some of them with miles-long chains. I’ve never had a chain come off, either inside or outside, that didn’t go away after some careful adjustment.

CrimsonEclipse

If you take off the chainguard, does the chain actually come off?
If so, consider a 'narrow/wide' chainring.