| | | | | | | | | Another strange one - Stronglight | | | | | |
Posted: Wed Sep 15, 2010 11:41 am |
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scozim |
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Joined: 26 Sep 2008 |
Posts: 629 |
Location: Ellensburg, WA |
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I was in the LBS today looking for some smaller rings for the bike I'm setting up as a touring rig and in the used box of parts pulled out a Stronglight 390 crankset. The cranks themselves are nothing that spectacular and they're 170 mm which is what I use.
http://tinyurl.com/2bhlrhv
But attached to the arms were some oblong (aka biopace style) rings that had a 48-48t count. The inner one said Stronglight on it. I wasn't aware that Stronglight made these oblong chainrings. Does anyone have some info on them? Velobase is lacking for this style.
"Unfortunately" I'm going to have to go back and buy the crankset from the shop owner - just too intriguing.
Scott |
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Posted: Wed Sep 15, 2010 5:48 pm |
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scozim |
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Joined: 26 Sep 2008 |
Posts: 629 |
Location: Ellensburg, WA |
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Went back and bought the crankset tonight while waiting for an emergency wheel true (after jumping the pannier off the rack and into the rear wheel on a parking lot entrance).
The crank arms are well worn and will need some polish and light sanding to get a lot of the scratches/scuffs out.
Here are the rings - called Bio Strong. The cranks can be run as a triple or double with a 110/74 bcd. There was no middle ring but the 48 and 28 Bio Strong rings. Gotta be from the 80's.
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| | | | | | | | | BioPace | | | | | |
Posted: Wed Sep 15, 2010 8:35 pm |
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verktyg |
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Joined: 14 Jan 2007 |
Posts: 2814 |
Location: SF Bay Area |
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Scott,
Shimano introduced their highly controversial Biopace elliptical type chainrings around 1983. They put a lot of effort into marketing Biopace especially on bikes with all Shimano components. Biopace faded away in 1992.
Many other crank manufacturers offered some elliptical type chainrings in the late 80s to try to get a piece of the Biopace action. Campagnolo and maybe T.A. where a few of the exceptions that didn't buy into it.
I'd heard that Stronglight made some elliptical type chainrings but I'd never seen them before. Those chainrings have a very aggressive elliptical design.
Shimano had 3+ versions of their Biopace design chainrings: original with a highly elliptical design, Biopace II, Biopace III and Biopace HP. The later versions had a very small amount of ellipse in the chainring design.
Sheldon Brown wrote a good article on elliptical chainrings.
http://www.sheldonbrown.com/biopace.html
I have Shimano Deore XT Biopace III triples on both my MTBs plus a set of them on one of my road bikes that I built for climbing.
It's hard to notice much difference offroad on the MTBs but for me the Biopace III triple chainrings make a noticeable difference when climbing on a road bike.
I've read that it's not a good idea to mix elliptical and round chainrings.
Shimano Biopace chainrings should fit on those Stronglight 309 cranks. You can also get round 110mm and 74mm BCD chainrings from a lot of manufacturers. |
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_________________ Chas.
SF Bay Area, CA USA
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1984 Criterium
1969 TdF
1971 TdF
1974 TdF
1984 TdF x 2 Bikes
1970 SC
1971 SC
1972 SC
1984 SC
1984 Team Pro
1985 Professional
1990s Team Replica |
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Posted: Wed Sep 15, 2010 11:36 pm |
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Gtane |
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Joined: 14 Sep 2007 |
Posts: 681 |
Location: UK |
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_________________ Everything has a cycle |
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Posted: Thu Sep 16, 2010 3:31 am |
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trailrunner |
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Joined: 21 Jul 2010 |
Posts: 20 |
Location: Fort Worth, TX |
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The sheldonbrown write up is very interesting - how there have been changes as to what point of the pedal stroke aligns with the higher or lower ratio. And it's effect on the knees. |
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_________________ Dave B
Ft Worth, TX |
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