Biopace Chainset Bent Spider?

[NorwichVelo]

I've stuck an old Biopace crankset on my winter bike but with new standard chainrings. I've notice that one of the arms on the spider seems set out further than the others or its just bent. I did a Google search and this seems to have happened to other people. I've set the outer limit screw on the front mech out a bit but I'm worried about the chain coming off.

This can't be a coincidence and I wonder if the spider has this feature to counter the mech set up with Biopace rings?

[meic]

I didnt notice any such thing on my Exage Trail Biopace chainset. I replaced the Biopace rings with circular ones without any difficulty.

I did have a problem with a lot of "wobbly" chainring, investigation proved that was due to the crankset not the rings.

I dont think that the cranksets are in any way Biopace specific, it was just the rings, I thought. I did have that bit of experience that fits your theory but I still think that was a dodgy taper hole rather than a feature of Biopace cranksets.

[Brucey]

unless there is some reason to believe the chainset has taken a knock, I'd suggest that a worn taper is likely to blame.

cheers

[NorwichVelo]

I couldn't rest not tying to sort it out and the rings and spider are not true. They were stronglight chain rings from my friends at Ribble and I've done a bit of research and they are for "light use" what a lad of crap. 52 and 39 for a pootle round the park? Marketing code for rubbish. Ho hum I'll use it for this winter and the chainrings will probably wear out anyway.

[Brucey]

if you mount chainrings of any kind to a spider that doesn't run true then neither will the chainrings. If you bolt a chainring to a spider with one bent arm then the chainring will likely end up bent too.

Whilst I don't think the stronglight chainrings are the best quality I'm not quite sure what you expect from them if the cranks are no good....?

cheers

[NorwichVelo]

Hi Brucey

I've now stuck and old worn campag 53 ring on and it's fine. The spider seems out of true not by much mnd but I've got no precise way way of determining this. It might just be my middle aged eyesight or the Eco bulb in the garage.

The tapers don't seem worn at all.

The chainrings are Stronlight Dural and are total rubbish not only is the outer ring twisted but the flanges that actually bolt on are twisted, Anyway I think I've got the mech set up to avoid any rubbing so I'll try and crack on and wear the buggars out.

I tryed to save money as chainrings are bloody expensive, but it never works. Had the sane thing with a rear mech when I went for Sora total crap. Anyway I'm off riding. Lesson should be learnt now... You get what you pay for!

Lastly one of the dads cane round yesterday asking if I could take the old freewheel off of his sons bike. I got to keep the old one and I've now got a shimano body. It's one of the Singapore ones too that seem better quality than the China ones so I'll stick the Sunrace outer body on that.