> 406mm tires are about 16-18" or so in diameter. I forget if 406 tires > are closer to 16" or 18". 73x13 with 406 gets you about 100 gear > inches. 52x28 gets you about 33 gear inches. Equivalent of a > sensibly geared compact double crankset today. I think 406mm is used > by Moulton bikes and foldable bikes. Bike Friday uses 406 I think on > their touring models. 420 on their racy models.
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Got a picture? It sounds like the crank would be almost as big as the tires and you would have a ground clearance problem. I don't recall ever seeing something like that in either of my LBS's.
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Now you've done it... Tom loves to post links to pictures of his bikes/trikes... check the archives. I'm 99.9% sure he's talking about a recumbent of some sort.
Provoking a reaction from the "upright uptights" is fun - and not to be confused with trying to convince others to ride similar human powered vehicles!
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I think that is likely the case, but it would still make for a good conversation starter, hopefully with a babe.
That bike (Wishbone) with the giant chainring provoked more freak show reactions than anything else. My current bike is equally as odd, but much more cute.
-- Tom Sherman - Holstein-Friesland Bovinia The weather is here, wish you were beautiful
On Jun 4, 10:38 am, VeloJon wrote: > According to Cyclingnews, several Giro riders were running 52/34 chain > rings for the big climbs. I thought the conventional wisdom was that > a 16-tooth differential between the 2 rings was the max for shifting > smoothness on the front der. Before I go and try a 52/34 combo, > opinions please? I used to run a 73/52 double on a bicycle with an ISO 406-mm drive wheel. Shifting with a Shimano RSX road derailleur was slow (no ramps and pins on the large chainring) but otherwise acceptable.
If you were running a gear like that just what the hell did you have in the rear? 73/?? seems way unlikely.
More likely than going downhill at 50 mph on a children's tricycle!
Enough tricycle already. 23 felt like 50 at age 4 or 5 when I did it.
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Note that I wrote ISO 406-mm drive wheel. With a Tioga Comp Pool tire, the 73/52 chainring and 11-28 cassette results in a range of 36 to 129 gear inches.
This is the bike, at the time of purchase <http://www.ihpva.org/ incoming/2001/wbone2.jpg> and shortly after I sold it: <http:// www.liegeradinfo.de/wisbone2.jpg>.
-- Tom Sherman - Holstein-Friesland Bovinia The weather is here, wish you were beautiful
On Jun 7, 12:57 am, Bill Baka wrote: > Johnny Sunset wrote: >> On Jun 4, 10:38 am, VeloJon wrote: >>> According to Cyclingnews, several Giro riders were running 52/34 chain >>> rings for the big climbs. I thought the conventional wisdom was that >>> a 16-tooth differential between the 2 rings was the max for shifting >>> smoothness on the front der. Before I go and try a 52/34 combo, >>> opinions please? >> I used to run a 73/52 double on a bicycle with an ISO 406-mm drive >> wheel. Shifting with a Shimano RSX road derailleur was slow (no ramps >> and pins on the large chainring) but otherwise acceptable. > If you were running a gear like that just what the hell did you have in > the rear? 73/?? seems way unlikely. > Bill Baka 406mm tires are about 16-18" or so in diameter. I forget if 406 tires are closer to 16" or 18". 73x13 with 406 gets you about 100 gear inches. 52x28 gets you about 33 gear inches. Equivalent of a sensibly geared compact double crankset today. I think 406mm is used by Moulton bikes and foldable bikes. Bike Friday uses 406 I think on their touring models. 420 on their racy models.
Got a picture? It sounds like the crank would be almost as big as the tires and you would have a ground clearance problem. I don't recall ever seeing something like that in either of my LBS's.
See post below for picture. The big ring started life as an aluminium alloy plate, and was custom machined into a chainring - hence the lack of "ramps and pins" seen on modern mid to high end commercial chainrings.
I looked, I saw, I'm still scratching my head. I'm not sure I would want to be seen on that thing. The big rings would be right in the line of sight. Bill Baka
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-- Tom Sherman - Holstein-Friesland Bovinia The weather is here, wish you were beautiful
