Grappling With Gearing

Questions about purchasing bicycles and parts

Grappling With Gearing

Postby rdp_au » Tue Mar 06, 2007 9:27 pm

I have an old Shimano Exage 400LX M400 system that has been migrated off a mountain bike onto a road bike. It is a seven speed system with 28-38-48 biopace chainrings and a 12-28 cluster. It works reasonably well, and I can't really afford to replace the whole thing, but I would like to extend the gearing range at the high end. Does anyone know if biopace chainrings are still available? Also, would an increase of four teeth still work with the same front deraillleur?
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by BNA » Tue Mar 06, 2007 10:04 pm

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Postby mikesbytes » Tue Mar 06, 2007 10:04 pm

Kieran, who works at Cell bikes has a larger biopace big ring on his racer.

You can also get a new cluster with an 11 on it. I've got one in 7 speed.

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11 tooth cluster

Postby rdp_au » Wed Mar 07, 2007 6:33 pm

Thanks for the info. I suspect that an 11 tooth will be too small. The clearance between the chain and rear stays is very tight with the current 12 tooth. That's why I was thinking of upgrading the chainrings. Biopace rings are pretty hard to find. By sods law I missed a nearly new biopace 50-38-28 set on ebay. Think I may just have to upgrade from biopace.

Cheers,

David
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Postby cludence » Wed Mar 07, 2007 7:10 pm

Hi, forgive my ignorance here because I dont play around with changing/adding chainrings very often.....Are you talking about the older 80's biopace? I get them in here quite often.

Let me know because I can send you some pics and happy to chuck some in the post to you.

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Postby mikesbytes » Wed Mar 07, 2007 7:43 pm

David,

What kind of cassette do you currently have? I'm not talking about adding an extra cog, but replacing the entire cassette. A 11 tooth cog will fit on all modern bikes.

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BTW did you contact Keiran? Go to the cell bike web site and get the shops email address. Keiran will respond about the biopace ring.
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11 tooth cog

Postby rdp_au » Thu Mar 08, 2007 11:18 am

From my reading the Sheldon bible, to fit an 11 tooth cog requires a 'compact' hub, where the splines don't extend all the way to the end. I had the cluster off mine a while ago, and I'm pretty sure it isn't. Anyway, I fear the real issue is chain clearance. This is a recumbent bike and the chain runs parallel and quite close to the chainstays when on the smallest cog. I think if the cog was any smaller, it would rub. Suppose the only way to find out is to give it a go.

Anyone got a 7 speed 11-28 cluster for sale? (I think it's Shimano code ac/aj)

Cheers,

David
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Chainrings

Postby rdp_au » Thu Mar 08, 2007 11:34 am

Cludence, these are indeed late 80's biopace rings I'm talking about.

What I'm chasing is a 50 tooth large ring to fit a 'compact crank (110 BCD). I think this is the largest (biopace) ring that will fit. This would create a 50-38-28 crankset, which it seems it is not an uncommon configuration.

Having said that, I have to confess that I'm not overly fond of the biopace on the road. Didn't really notice it much when it was on the mountain bike and most riding was off-road. But on the road it seems to produce an annoying surge on each pedal stroke that feels inefficient.

Eventually what I'd like to do to bite the proverbial bullet and spend the money to replace all the chainrings with a normal touring setup.

Cheers,

David
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Re: 11 tooth cog

Postby MichaelB » Fri Mar 09, 2007 8:45 am

rdp_au wrote:

Anyone got a 7 speed 11-28 cluster for sale? (I think it's Shimano code ac/aj)

Cheers,

David


Yep,

Comes with a Diamondback Mountain bike for free :)
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Cluster with free bike

Postby rdp_au » Fri Mar 09, 2007 9:37 am

Comes with a Diamondback Mountain bike for free


And how much would the cluster be??

Cheers,

David
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Postby mikesbytes » Fri Mar 09, 2007 9:50 am

Have you got a standard Shimano 9 speed hub? If so, you can simply put a Shimano 7 speed cluster on with the aid of a spacer.

Don't bother buying a second hand cluster off anyone, they wear with the chains, mixing sets often doesn't work.

If you know exactly what you want, and $$$ is important, get one mail order from one of various sites such as www.probikekit.com or www.torpedo7.com.au or www.cellbikes.com.au etc.

If you don't know exactly what you want, just drop by at the LBS and get one, if they don't have exactly what you want they can order it, otherwise go to a different LBS.

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Re: Cluster with free bike

Postby MichaelB » Fri Mar 09, 2007 9:52 am

rdp_au wrote:
Comes with a Diamondback Mountain bike for free


And how much would the cluster be??

Cheers,

David


Just counted the teeth the other night and I don't know what a new one looks like, but I think that this has had it's fair share done.

As to price, how much do i need to finish the layby on the new LeMond , Ummm $679. Yep, how does that sound ? :D

In reality, if the bike was worth $150, i'd take it, but I feel that is a little too much just for a rear casette that has been through a few km's.... 8)
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