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jcarneytx

Anyone want to do the math?

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38t chainring

28t cog

32t cog as 2nd chainring

Looks like maybe standard 11-25 or 12-27 cassette

There is no reason for that complexity.  By my calculations (coffee still fully not kicked in) that gives them final ratio of 1.61 (assuming 27t cog) to 3.94 (assuming 11t cog).

A road triple 53/39/30 would give them a bigger range.

Shoot, even a compact 50/34 would be better.

 

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13 hours ago, AntonioGG said:

38t chainring

28t cog

32t cog as 2nd chainring

Looks like maybe standard 11-25 or 12-27 cassette

There is no reason for that complexity.  By my calculations (coffee still fully not kicked in) that gives them final ratio of 1.61 (assuming 27t cog) to 3.94 (assuming 11t cog).

A road triple 53/39/30 would give them a bigger range.

Shoot, even a compact 50/34 would be better.

 

2nd upper chainring has a derailleur, as does the actual crank/chainrings. The only "non-moving" chainring would be the upper to the back wheel (needs to stay where it is or interfere with adjustable chain. So you'd have (guessing) a possible 42 or 34 at crank, possible 12-28 upper gearing and say 12-32 on back wheel. At top end you'd have 42:12:12 ratio and at bottom 34:28:32.  I'd say a bit more than just a normal trippel (final gear speed, anyway)

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I downloaded the picture really zoomed in and counted the teeth.  It's a 38th big ring on the crank (weird size I know).  I also counted the two cogs on that "idler" cassette.  I'm pretty sure 28t and 32t are right.

I hadn't realized there was a cable on that upper derraileur.  I thought it was being used as a tensioner.   The small gear looks to be a 15t by my count.

The only one I couldn't count was the cassette on the wheel, but it doesn't look like a very large one.  It looks like the one on my road bike (11-25).

38:15:12 for top speed 7.36:1 final ratio  Not even a 60t chainring with 11t cog would compare.

28:28:?   If it's a 25, that's a ~1.3:1 ratio.  A 27 would be ~1.18:1.  A 32 would be 1:1 ratio

 I want to see the cockpit on this thing!

If they wanted low gearing, then a MTB triple would be way better with a <1 ratio possible with a 22t granny in a triple crankset.

If they wanted high gearing, then, this is one way to do it I guess.  But so is this 🙂

https://www.velonews.com/2016/09/news/ca-woman-rides-her-bicycle-147-mph-a-new-world-record_420507

Ultimately, it seems like an art bike and pretty cool if it works, but seems highly impractical.

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Perhaps it is a bike owned by a Semi-Tractor driver who enjoys having a ridiculous number of gear combinations with lots of shifters to fiddle with.

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10 hours ago, Shinerider said:

Holey shit the rain is driving ya'll bat shit crazy.

Better than arguing with certain people about inane things!  At least we're discussing cool/weird bike things here and nerding out.

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