Sorry if this has been covered in a previous thread. Actually i'd be surprised if it hasn't, though i couldn't find such a thread.

Anyways, i am sort of modernizing what was a Takara 10-speed mixte from the late 70's. I'm ditching the derailuers and rebuilding the rear wheel with a Sturmey-Archer 8 speed hub. Along the way, i'll also be replacing the a few other components. I was thinking it'd be nice to put on a chainguard too (the kind that goes over the top of the chain and kind of wraps around the chainring, not a full chaincase). They seem to be readily available on ebay. Most of them are take-offs from old cruisers, stingrays, etc. Some, such as this are new and meant for lowrider-type bikes. I'm wondering how exactly these things are mounted and weather or not they're a one size-fits all type thing. It seems to me they probably aren't, since they would need to have varying radii for the front part to accomodate different chainring sizes. But none of the ones i've seen for sale have any such specifications listed, so maybe i'm wrong.

Does anybody have any experience fitting a chainguard to a bike it wasn't designed for?

Just from personal experience, I would recommend the Nexus hub over the SA 8 speed. The SA hub has really funky gearing with its lowest gear being direct drive (instead of putting it in the middle)

If you can find one which clamps to the chain stay and to the downtube I think you should go with that one, as they can be moved around a fair amount so you shouldnt have too much trouble adjusting to your frames geometry, rather than using the really long type which clamps to the seat stay by the rear cog and your downtube. I think your best bet would be to use one from the 70s or 80s that came off a 3 speed or single speed.

I think the SA 8 speed is intended for folders with 20 inch wheels.

yeah, i realize the Sturmey-Archer is pretty weird, with the direct drive as the lowest gear, but i've already bought it. plus, it's significantly ($60-$80 including the shifter) less expensive than the Shimano. They compensate somewhat by supplying a rather large cog (25T) and i'm going to be using a fairly small chainring (34T). This will give a low gear of ~36 inches, which i am hoping will be low enough for my mom, and a high gear of ~108 inches, which i suspect will be useless. Oh well. If it turns out that these gears are too high, i guess i'll have to go down to a MTB crank with a smaller BCD than 110mm.

The Velo Orange blog has had a few recent entries on chain guards, and I believe VO is selling a Simplex model (though he might be already sold out): https://velo-orange.blogspot.com/

Neal

Great timing on that link! I picked up an old Peugeot for my wife last night that looks exactly like the 53' PX45 in the blog. It's missing the chainguard and a few other small bits but is mostly intact and should be rideable once I get new rubber on it. Definately the oldest bike I've ever owned. I'll be back with pictures and questions soon.