3 chainsets, can't use anything with anything!

Manc33

Got three complete chainsets here, wanted to lighten up my new 130 BCD chainset with the chainrings off two old touring bikes. Forget it lol. :roll:

Stronglight - 51mm between bolts / 86 BCD - Obsolete
Shimano Biopace (FC-B124) - 65mm between bolts / 110 BCD
Prowheel Ounce - 75mm between bolts / 130 BCD
http://sheldonbrown.com/cribsheet-bcd.html

Bike component manufacturers Y U keep changing everything!

Oh well the Biopace crank arms are only about 50g lighter overall anyway, over the newer Prowheel Ounce.

That Prowheel Ounce is on a £300 bike and it only weighs 800g. Well I was looking at super expensive carbon crank arm setups and about the lowest I saw was 600g and you're looking at a re-mortgage.

I won't use the complete Biopace chainset (which is possible, they all have a square taper!) because the chainrings are oval shaped, ewwwwww. I can't use the Stronglight because the left crank arm is missing. I can't use the other Stronglight because the plastic end cap seized into the metal and I can't get the 14mm socket in to loosen it, oh and the pedal cannot be removed with the Park Tool PW-5 even with a towel around it and a rubber hammer hammering it, was swinging my arm like 2 feet absolutely leathering it and it won't budge.

Sometimes you just think God must be looking down on you... and laughing...

Manc33

Guys, can you even buy carbon crank arms in a triple anymore? All the ones I have seen (new or used) are all for doubles.

£134 for a used set but it does have BB and chainrings on it...

http://www.ebay.com/itm/FSA-Carbon-Pro- ... 7675.l2557

Can't justify the cost to be honest. Not to save 200g or whatever it ends up being.

k-dog

You'll have a lot more luck getting the pedal off if the crank is on a bike. Put the front wheel against a wall so it can't go anywhere, get the crank roughly horizontal and the spanner horizontal too. One foot on the cranks and the other on the end if the spanner and then transfer your weight to the spanner - that's a lot more force than your hammer. Never failed yet with that one.

gozzy

Manc33 wrote:

I won't use the complete Biopace chainset (which is possible, they all have a square taper!) because the chainrings are oval shaped, ewwwwww..

What's wrong with them being oval? Nothing.

cycleclinic

Carbon cranks may be 600g but that includes a integrated axle. So let take Camapag record double with BB cups is weight a bit under 700g. Your pound cranks will be square taper probably and that means a 300g BB So there is 400g difference may be depending on the BB used.

You can still buy 86mm BCD chainrings, I have had to for customers.

maddog 2

biopace is ancient man! Knocking on 30 years old...?

You can't easily have flexibility and generality in design simultaneously. If everything was compatible with everything else then the speed of change is slower, and it's harder to have specialist parts, and some designs would be compromised as a result. For example, if all crank spiders were mtb 4-bolt then you could have any ring from 32t upwards, but then a 53t ring would be flexy. So you have a 130mm BCD spider and the 53t ring is nice and stiff, but then you can't go below 38t ... can't have it both ways. It's the way design is.

rolf_f

Gozzy wrote:

Manc33 wrote:

I won't use the complete Biopace chainset (which is possible, they all have a square taper!) because the chainrings are oval shaped, ewwwwww..

What's wrong with them being oval? Nothing.

Indeed - has the OP even ridden them. I have a bike with Biopace rings - makes no difference whatsoever!

Bizarre concept trying to lighten a bike by using the chainrings off a touring bike - presume the rings are all much smaller than the road triple rings? That'll save weight but not exactly help you go faster.......

gozzy

Biopace are fine, it's no matter that they're 30 years old. Rotor Q rings work on the same principle, and I'm not sure if any technologically forward pro cycling teams use them...

Monty Dog

The problem with Biopace was that it was the right idea wrongly executed i.e. the effective diameter was narrowest at the point of peak torque to try and give a smooth pedal stroke, not to optimise power output. Q-rings and the like align max diameter with maximum torque.

rolf_f

Monty Dog wrote:

The problem with Biopace was that it was the right idea wrongly executed i.e. the effective diameter was narrowest at the point of peak torque to try and give a smooth pedal stroke, not to optimise power output. Q-rings and the like align max diameter with maximum torque.

No, it's a different idea correctly executed.

Monty Dog

Then with all the might of Shimano's marketing muscle behind it, didn't it catch on?

rolf_f

Monty Dog wrote:

Then with all the might of Shimano's marketing muscle behind it, didn't it catch on?

Ever heard of Betamax? All sorts of things don't succeed that should. Possibly it didn't succeed because it didn't really need to be invented - the benefits, if present, are pretty subtle; I'm not consciously aware of them. Q Rings will probably be long forgotten in 10 years time as well (though these days the internet ensures things are remembered for longer than they once would have been. Of course, back then all the might of Shimanos marketing muscle would have been the odd poster in a shop plus the product on various bikes and nothing more - even the catalogues only tend to specifically mention Biopace in the spec sheets. The conservative buying public would have needed more than 'try these odd shaped rings, they'rrreee great!').

ugo.santalucia

Rolf F wrote:

Ever heard of Betamax? All sorts of things don't succeed that should.

That's an interesting story... one of my favourites. The reason VHS took over the tape market was because it was a cheaper system, but wait a minute, it wasn't the customers who abandoned Betamax, but.... the porn industry decided to go VHS... once that was set, there was no real choice, as the ONLY reason to buy a VHS at the very beginning was to watch porn at home

Manc33

I rode that exact same chainset on a "Specialized Rockhopper" in the 1990s and the teeth on the middle ring turned into "sharks fins" well within 1000 miles. Maybe because they are oval? The (same) chainset I have now isn't all worn like that but then it hasn't been ridden as much. Can't justify swapping to it to save 50g. Its 172.5mm anyway not 175mm and I have super weak legs.

Not even been on my bike for about a week because of this weather. If its not raining its 40 MPH winds.

Got a 6 speed (13-32T) Suntour cassette here, guess what it weighs? 496g :shock:

Compare that to my £12.99 SRAM PG-850 (12-23T) road cassette @ 188g.

Oh yeah the freewheel is built into the Suntour, my bad. :oops:

maddog 2

as MD says, biopace was a different idea to Q-rings, with the oval the 'other way' in an attempt to smooth out the pedal stroke, rather than maximise torque like the Q/oval/ossymetric rings do.

It's an interesting idea (biopace) as pedalling off road, in the early days of fully rigid mtbs, was a bumpy, jangling affair where it was all to easy to end up bouncing up and down on the seat as you pedal. This bouncing can be mediated in a number of possible ways:

- by going to a higher gear and reducing your cadence. This works (and still does) as the legs are spinning slower, so it's easier to take more weight on them, and off your bum.
- by inventing rear suspension (and to a lesser extent suspension seatposts).
- by riding on smoother trails, like you see on most trail centres these days
- or by attempting to slow the pedal stroke down, for a given cadence, like Shimano attempted to do with biopace. in an attempt to reduce bum bounce. Except nobody really liked it. Maybe it was the early days of mtb and people weren't up for new ideas...? Maybe the pros weren't on it...? Maybe the shifting was dodgy? Maybe it was just weird and rubbish? I didn't use it at the time so... who knows.

None of this is relevant to the OP of course, who should just buy some modern kit and move on.

rolf_f

maddog 2 wrote:

. Except nobody really liked it. Maybe it was the early days of mtb and people weren't up for new ideas...? Maybe the pros weren't on it...? Maybe the shifting was dodgy? Maybe it was just weird and rubbish? I didn't use it at the time so... who knows.

Prejudice probably. TBH, Biopace is very subtle - as is the shape of the rings. You have to look at them properly to see that they aren't round and the effect is equally subtle on the bike. Shifting is fine and the pedal stroke, in conscious terms, feels exactly the same as with round rings. Any benefits will be down to feeling less fatigued over the course of a ride which, of course, is not easy to quantify. In comparison, I imagine that it must be pretty obvious riding with Q rings.

I suspect that the truth was that the benefits weren't obvious enough to draw people to Biopace but the conservatism of many buyers was enough to put some of them off. On that basis there would be no point in continuing with Biopace irrespective of whether or not it actually worked.

Manc33

On an oval Biopace chainring the chain doesn't just move over the top of the chainring like on a round chainring, it moves up and down as well. It might only be moving up and down 2mm or 1mm, but it does have that "added movement" to it. I am pretty sure thats why the middle chainring wore (to shark fins) so fast.

I don't know if aluminium has come very far in 25 years, has it?

The 25+ year old Stronglight and Biopace aluminium chainrings seem like a softer aluminium, seem to wear faster, get scratched easier and so on. On my new Triban 3 they are I am sure aluminium again, but the black anodizing is the only wear on them after over 1000 miles.

25 years is an eon in computing but in metallurgy?! I would think by now aluminium is about as good as it can get.