MNBiker

About a year ago I acquired a Miyata 615 touring bike, which I have really enjoyed for commuting. I think it's from the early '90's.

I recently learned that the middle chainring, which I (and apparently the last owner) use most often, is exceedingly worn, as well as the freewheel and chain.

The chainrings are 28T, 38T, and 48T and they are biopace. It's the 38T biopace that is badly worn -- the others are okay. It has a 110 BCD measurement. I would like to minimally replace the 38T chainring.

I find that Shimano biopace are no longer made. I have looked on ebay for NOS or good condition 38T biopace with 110 BCD, but have only found a few for sale with questionable wear on them (they don't specify). Mostly they offer biopace for road bikes with different sized chainrings and a different BCD measurement.

Can anybody point me to good places to look to find a compatible Shimano biopace chainring that I can use to replace my 38T, for an inexpensive amount?

I don't know much of anything about crank and chainwheel compatibility. Is it better to look for a whole crank than just to replace the chainring(s)?

Thanks for any help!

BLACK BIKE

Have you tried looking here?

Panthers007

I have a triple Biopace crankset from an old mountain-bike from 1984 - square-taper and loose-bearings. They need a little work, starting with taking 'em off the old frame and examining then and cleaning. I keep meaning to get around to this.

I am not willing to sell them. If they are, and they undoubtedly are, still good - they rode great! There was no "dead-spot" in the crank revolutions. It was all straight power-transfer all the way around the pedal-stroke. You'd go a little further and faster for the same energy expenditure. They were/are 46-36-26T alloy.

I wish you luck in finding a set at a reasonable price. And with folks like BLACK BIKE inferring they belong in a dumpster - you just might get 'em cheap, too! Look for a dumpster with a stupid guy with buck-teeth and holding a set of vice-grips standing next to it. Seriously - keep at eBay for them. Or maybe also put out a WANTED ad of your own.

kramnnim

...are you set on Biopace? You might be better off replacing the entire drivetrain...the old chain won't work well on the one new chainring, and a new chain wont like the two old ones.

I think I might have a 110mm 38T Biopace ring kicking around...

MNBiker

Thanks for the positive word Panthers007. I do plan to continue to look at ebay. I just thought someone here might have a better way.

I would like to try to keep the biopace if I can, but I suppose at some point I might give up if I can't find a replacement biopace. Whatever I do I need to keep the expense down right now, just because of my current financial situation (I'm between jobs but I had a second interview today. That's good!).

As far as replacing the entire drive train -- I plan to do that. I am just waiting to get the new chainring before replacing the chain and freewheel as well.

kramnnim, if you do run across a 38T biopace in decent condition that you are willing to part with, send me a pm and we can talk. Thanks. For now I will keep watching ebay. I have tried looking at the used parts bins at a couple of LBS's, but haven't found anything good.

MnHPVA Guy

I sell NOS BioPace rings and I'm here in Minneapolis too.

Contact me at mark@bikesmithdesign.com if you want some.

Jeff Wills

Mark is Da Man...

On the other hand, I removed a lot of Biopace chainrings from Shimano cranks back when I worked at Euro-Asia Imports. I'd bet they still have boxes of them...

noglider 

I may have one.

jtgotsjets

Dude, don't be a dick.

miamijim

I laughed because thats where mine are!!!

I'll check later today....if I have a 38t the OP can have it for free.

Jim

snappy

i have one that i took off my own miyata 615. if nobody else has own, i can mail you mine.

it's a pretty sweet bike, isn't it? mine is an '87.

MNBiker

Wow, I'm overwhelmed with the response! I don't have time to deal with this now. I will get back to this later today or on the weekend.

Thank you.

lverhagen

Hey, I usually hang out in SS/FG but decided to look around some more. I happen to have a complete set of 28-38-48 biopace chainrings in good condition and 110 bcd from an older mtn bike. pm me if you want them.

RFC

I have Biopace on both my Univega Gran Touring and my Trek 660, and actually like it. Did the middle CR come only in 38t or can you get a 36t or 34t?

miamijim

No have. I either pitched 'em or gave them away awhile back.

CardiacKid

Apparently there are 2 types of people on this forum; those that have a set or 2 of Biopace cranks in a box in the garage and those that have them on their bikes. Count me among the former.

top506

'Biopace' denotes chainrings, not cranks, my snarky friend.
I fit into both camps; rings on my bikes and a stack in the barn to replace those that are worn.
Top

cyclotoine

This summer I acquired quite a biopace stash, problem is I don't have a bike to try them on! The 38t is too big for loaded touring (I like 24/36/46 with an 11-32 8s)... and all my other bikes are either fixed gears or 10 in the back with the exception of the vintage road bikes that are all campy.. sheesh! I'd actually like to try them out at some point.

BLACK BIKE

I'm not trying to be a dick. It's genuine advice, since that's where I put the last set of Biopace chainrings I came across. I know of a few other people who have placed their's in a similar receptacle too.

Panthers007

Which may work in the favor of people who want them. Not because they're in a trash-can, but rather as others may think this means they're worthless and sell 'em for pocket-change.

johnknappcc

Can anyone actually tell the difference? I know they got a lot of heat, I used my biopace 50/44/28 for 18 years, and then switched out the chainrings to regular round Sugino's, now moving to a R700 compact double, and I can't tell a difference at all. Seriously, can anyone?

No speed changes, no differences in cadence, for the life of me I can't tell.

Panthers007

Read my first post - in this thread. YES. No 'Dead-Spot' in your pedal-revolution. You go a bit further, and a bit faster, for the same expenditure of energy. They are also said - by many - to lower the pain of those with knee injuries.

What I wonder is: What do people (granted there aren't that many) who started cycling with Biopace-rings think when they ride the traditional round ones? Anyone?

johnknappcc

That's what I mean, for 18 years (since I was 12) biopace. Put the new Sugino's on (two months ago), same tooth sizes, and I can't feel any difference. At all.

Also, I heard that it actually hurts some people knees. Not mine, just saying.

bikegeekmn

I'm pretty sure bio-pace only had 36-38 as a middle for a triple.

BengeBoy 

Some biopace chainrings came set up for half-step gearing. I have two that are 47-ish (I think).