Utility bike Biopace replacement

UserError

Über Member
Location
West Sussex
Hello, I have an old Giant Euro hybrid (?) bike which has 21 speed Biopace chainrings etc. My son used it for a number of months and when the chain started slipping, did nothing about it, so now you can't really get any traction at all.
I'd now like to use it to cycle to the shops etc with a trailer and I'm looking to replace any or all of the drivetrain but not sure what to get: I'm presuming the cassette will be trashed, along with between 1 and 3 of the front chainrings plus chain.

I would assume that the front and rear mechs wont necessarily be ruined?
What I don't know, and get bogged down whenever I've tried to resolve this, is out of all of the hg/sg/ etc etc stuff, what is compatible?
I can easily do the mechanics, just that I lose the will to live with all the shimano options.
Can anyone offer any guidance on a 7 speed cassette and front chainrings. I would plan to get this from eBay or wherever...?
Many thanks
 

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Drago

Flouncing Nobber
Location
Poshshire
Greetings.

Alas, it's not likely to be financially viable to replace the entire drivetrain unless you've some particular emotional attachment to that bike. Without pictures of the components concerned, it may be possible to get away with a new chain and cassette (or freewheel, depending on which the bike has).

Any chance of some pics of the gears and chain set?
 

C R

Veteran
Location
Worcester
Greetings.

Alas, it's not likely to be financially viable to replace the entire drivetrain unless you've some particular emotional attachment to that bike. Without pictures of the components concerned, it may be possible to get away with a new chain and cassette (or freewheel, depending on which the bike has).

Any chance of some pics of the gears and chain set?
Why would it be not viable? I don't think the op wants a biopace replacement. A cassette/freewheel, a chain and a reasonable chainset can be had for no more than 60 to 70 squids, all Shimano.
 

Drago

Flouncing Nobber
Location
Poshshire
Alas, the OP's late 80's Giant is not worth 60 or 70 quid. No offence meant.

That's not to say he couldn't spend 70 quid fixing it up I'd he wanted to, it's his bike to do with as he pleases.
 

Cycleops

Legendary Member
Location
Accra, Ghana
From what I can see the chain rings look toast.
As @C R says it's quite an easy fix, any square taper chain set will fit. You need to check if you have got a cassette as it's more likely a freewheel with seven speeds. A chain to complete. Check for any play in the BB too.
As @Drago points out it's not an economic repair but it should give you bike that will run for many more miles.
 

C R

Veteran
Location
Worcester
What I mean is that getting the bike up to working condition, even if a new bottom bracket is also needed, will still be cheaper than a new equivalent bike.
 

Drago

Flouncing Nobber
Location
Poshshire
I've bought better condition bikes for £30, with fully operation drivetrains with minimal wear. I've given away bikes with decent drivetrains because no one wanted to buy them.

Physically, an easy fix. Economically, there's simply no justification if the entire drivetrain needs replacing. That's not to say he shouldn't do it, but he came here asking for our advice.
 
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OP
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UserError

Über Member
Location
West Sussex
Screenshot_20190806-083818.png
Thanks. I have no attachment to the bike, just not one for chucking stuff away without a little effort first. The thing in it's favour is that it is more of a hybrid frame I think, so a bit more upright. I wasn't bothered about the Biopace, it just gives an indication of the bike's generation.

To get a replacement bike, I'd have to spend an hour each time, going to see one or more bikes till I found a decent one. And to ensure I was happy that it wasn't stolen as the sub £100 category must have a fair few hot bikes and I don't want to reward criminals.

If, for £30-50 I can get this going that seems reasonable to me. I don't mind buying serviceable used parts, or Tourney grade stuff - I'll just be going to the shops or wherever and not thousands of miles each year. And if I bought a secondhand bike, the parts would be used: is new Tourney better than used Alivio?

It seems a shimano freewheel starts ca £10 and a crankset/chainrings can be had for £15-40+, plus chain. Before posting, I looked for a bike on eBay and Gumtree and there was nothing locally worth looking at, at least for the the cost of sorting this one.
Cycleops indicated that any triple chainring would work (eg FC-M371)? And
I've seen this basic freewheel:
https://www.ebay.co.uk/itm/Shimano-...738415&hash=item35d406d99d:g:iz8AAOSwnIVdI1-5

or, this, in the attached photo, which doesn't look too worn to me, but I'm not experienced.
Many thanks.
 
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UserError

Über Member
Location
West Sussex
FWIW, this is the state it's in currently...
IMG_20190806_095137.jpg
IMG_20190806_095117.jpg
 

KneesUp

Guru
You can replace those chain rings easily enough, but you can't get Biopace new anymore (unless it's new-old-stock) I replaced my middle ring with a round one from Spa - it was around £20 iirc, so £60 for all 3, obviously. My inner and outer rings are still fairly decent as I got the bike second hand and I don't think they had been used much by the previous owner. If you just want to get it going, you can get a triple from Decathlon for £20, although the Shimano one at £25 may be worth the extra - it has changeable rings and may well be lighter. I have one of the Decathlon ones and it's fairly heavy.

https://www.decathlon.co.uk/C-2438052-cranksets#product_8063311

I'd replace the cassette and chain too, obviously, but there is no need to get anything fancy.

EDIT - link to Decathlon
 
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C R

Veteran
Location
Worcester
You can replace those chain rings easily enough, but you can't get Biopace new anymore (unless it's new-old-stock) I replaced my middle ring with a round one from Spa - it was around £20 iirc, so £60 for all 3, obviously. My inner and outer rings are still fairly decent as I got the bike second hand and I don't think they had been used much by the previous owner. If you just want to get it going, you can get a triple from Decathlon for £20, although the Shimano one at £25 may be worth the extra - it has changeable rings and may well be lighter. I have one of the Decathlon ones and it's fairly heavy.

I'd replace the cassette and chain too, obviously, but there is no need to get anything fancy.
What 'e said. One thing in favour of getting new rings instead of a new chainset, is that a new chainset may need a different spindle length, which would require replacing the bottom bracket. Looking at the photos, getting that bottom bracket out may or may not be straightforward.
 

Cycleops

Legendary Member
Location
Accra, Ghana
The chainset you pictured would be fine also the freewheel and chain. As @C R says getting the bb out to service it might be fun.
One thing you need to check before going ahead is the rust between the chain stay and rear dropout, cant see properly but if it's rusted through then the frame is a gonner. Can you move the seat post?
 
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UserError

Über Member
Location
West Sussex
The chainset you pictured would be fine also the freewheel and chain. As @C R says getting the bb out to service it might be fun.
One thing you need to check before going ahead is the rust between the chain stay and rear dropout, cant see properly but if it's rusted through then the frame is a gonner. Can you move the seat post?
Thank you for this info. I'll check those things out.
 
OP
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UserError

Über Member
Location
West Sussex
Knees Up. I did wonder about changing the rings, either en bloc, or as I find suitable oned on eBay. Or buying a crankset and taking the rings from it. Lots of options :wacko:
...or I found a Raleigh sit up and beg gent's bike about 25 miles away. I could see myself on that :-D
 
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