Pinion and Fixed-gear?
01-02-17, 01:12 PM
#26
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When I started, bicycling itself was a fringe activity, and the domain of oddballs and misfits. (not counting children).
With fixies as trendy as they are now, I suspect that there are more fixie riders today then there were adult bicyclists in the USA in the mid sixties.
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WARNING, I'm from New York. Thin skinned people should maintain safe distance.
01-02-17, 01:53 PM
#27
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I don't see a problem with using a BB epicyclic (planetary) drive with a fixed gear hub. It might actually be more mechanically efficient, though that shouldn't be a factor.
As for gear lash, that's simply a sub category of backlash which is an issue in mechanical systems. Both because of manufacturing tolerances, and to ensure low friction operation, systems are built with a bit of play. So, there's a bit of free play between the parts when engaged forward and reverse. In a car, you hear and feel it as a click (or clank) when you shift from forward to reverse.
If you've been riding fixed for a while, you know about this already. You keep a bit of slack in the chain to allow for the eccentricity in the sprockets. When you reverse torque the tension shifts from the upper to lower loop, and there's a bit of backlash you can feel in the pedals. IME, with the hubs I've used, the internal backlash is no more than that in the chain, so I don't consider it an issue.
Of course, whether hub backlash is an issue at all depends on the relative precision of the hub vs. sprockets, and how tight you can safely run the chain. Unless it's extreme, you adapt and don't notice it when riding.
As for gear lash, that's simply a sub category of backlash which is an issue in mechanical systems. Both because of manufacturing tolerances, and to ensure low friction operation, systems are built with a bit of play. So, there's a bit of free play between the parts when engaged forward and reverse. In a car, you hear and feel it as a click (or clank) when you shift from forward to reverse.
If you've been riding fixed for a while, you know about this already. You keep a bit of slack in the chain to allow for the eccentricity in the sprockets. When you reverse torque the tension shifts from the upper to lower loop, and there's a bit of backlash you can feel in the pedals. IME, with the hubs I've used, the internal backlash is no more than that in the chain, so I don't consider it an issue.
Of course, whether hub backlash is an issue at all depends on the relative precision of the hub vs. sprockets, and how tight you can safely run the chain. Unless it's extreme, you adapt and don't notice it when riding.
The Schlumpf bottom bracket has quite a bit of lash on it's own.
01-02-17, 02:13 PM
#28
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I have never paired a multi speed fixie hub with an epicyclic bottom bracket, but I own an example of each of these on separate bikes, and I think the accumulated lash between the two would be approaching extreme.
The Schlumpf bottom bracket has quite a bit of lash on it's own.
The Schlumpf bottom bracket has quite a bit of lash on it's own.
However, backlash is commulative, so each source adds it's share to the total. My old car was a good example, worn U-joints, differential and gear box were such that I could park it in gear and push it back and forth more than a foot.
FWIW - I don't know about modern offerings, but with my vintage 2s SA hub, I'd have less total backlash than many other fixed gear bikes. Part of that might be the old Campy Record drive train which allowed very close chain slack adjustment.
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
01-02-17, 04:03 PM
#29
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Having ridden multiple speed fixed gears on and off for years, I can tell you that it's like eating your cake and having it too. You enjoy the various benefits of fixed gear riding, yet have expanded hill climbing capabilities.
Or you can set the up hub with higher gearing than otherwise, knowing that you can downshift if/when needed. My 2 speed fixed hub is set up roughly 10% higher than I normally ride fixed, giving me a higher cruising speed on the flats, yet still giving me the flexibility for hills.
Or you can set the up hub with higher gearing than otherwise, knowing that you can downshift if/when needed. My 2 speed fixed hub is set up roughly 10% higher than I normally ride fixed, giving me a higher cruising speed on the flats, yet still giving me the flexibility for hills.
I suspect it will be a niche market and weight is a concern for me but really appreciate the explanation. Thanks.
01-02-17, 04:06 PM
#30
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In any case, it seems that the OP also wants to explore the options within this crevice, hence his questions and the answers.
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
01-02-17, 06:34 PM
#31
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thanks everyone, I guess I should have been more specific
My question was whether or not anyone has used a bottom bracket mounted gear system (like Pinion's) to make a geared fixie. I'm well aware of the fixed gear hubs, but I've read that they just don't feel right. Someone was talking about gear lash, could someone please explain that concept to me?
My question was whether or not anyone has used a bottom bracket mounted gear system (like Pinion's) to make a geared fixie. I'm well aware of the fixed gear hubs, but I've read that they just don't feel right. Someone was talking about gear lash, could someone please explain that concept to me?
Perhaps the McGill University library is a Place to go doing more reading they may have books on Engineering to read ,,
This forum is not the world, those Pinion Trannys were made by Studying Porsche Transmissions as I heard
And developed in a German University engineering Post grad Lab. ..
They add several thousand dollars to a Near custom frame build
and the Company in Germany, has a Website
So you may have to do your own research If nobody bought one for You.
(Im sure if you got one shipped to Dan Burkhart He will love to do a dissection & see how it works. )
...
01-02-17, 07:13 PM
#32
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But back to the original question, I did some searching to try to find out if the Pinion gearbox has a freewheeling chain ring, and while I could not find anything that addressed it directly, I did see a couple of short clips within some videos that appear to show that it does indeed freewheel. I think this would in fact be necessary due to the rising pawl gear engagement mechanism on the counter shaft.
Therefore, if coupled with a fixed rear hub, you would still have a bike that coasts.
The only geared bottom bracket I am aware of that does not freewheel is the Schlumpf. I know it does not, because I have one on a bike equipped with a coaster brake.
The Hammerschmidt two speed bottom bracket freewheels. I know this because I test rode one, and the Patterson freewheels, which I know to be true because Sam Patterson told me so.
The Efno 3 speed bottom bracket also freewheels as I understand it.
So, if it's a multi speed fixie you want using currently available off the shelf parts, it looks like the S3X Sturmey Archer or a Sclumpf drive are the only options.
01-09-17, 10:22 PM
#33
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Ha, you're right about that. Actually, I think I already have a pretty good idea how it works based on the pictures and drawings I've seen.
But back to the original question, I did some searching to try to find out if the Pinion gearbox has a freewheeling chain ring, and while I could not find anything that addressed it directly, I did see a couple of short clips within some videos that appear to show that it does indeed freewheel. I think this would in fact be necessary due to the rising pawl gear engagement mechanism on the counter shaft.
Therefore, if coupled with a fixed rear hub, you would still have a bike that coasts.
The only geared bottom bracket I am aware of that does not freewheel is the Schlumpf. I know it does not, because I have one on a bike equipped with a coaster brake.
The Hammerschmidt two speed bottom bracket freewheels. I know this because I test rode one, and the Patterson freewheels, which I know to be true because Sam Patterson told me so.
The Efno 3 speed bottom bracket also freewheels as I understand it.
So, if it's a multi speed fixie you want using currently available off the shelf parts, it looks like the S3X Sturmey Archer or a Sclumpf drive are the only options.
But back to the original question, I did some searching to try to find out if the Pinion gearbox has a freewheeling chain ring, and while I could not find anything that addressed it directly, I did see a couple of short clips within some videos that appear to show that it does indeed freewheel. I think this would in fact be necessary due to the rising pawl gear engagement mechanism on the counter shaft.
Therefore, if coupled with a fixed rear hub, you would still have a bike that coasts.
The only geared bottom bracket I am aware of that does not freewheel is the Schlumpf. I know it does not, because I have one on a bike equipped with a coaster brake.
The Hammerschmidt two speed bottom bracket freewheels. I know this because I test rode one, and the Patterson freewheels, which I know to be true because Sam Patterson told me so.
The Efno 3 speed bottom bracket also freewheels as I understand it.
So, if it's a multi speed fixie you want using currently available off the shelf parts, it looks like the S3X Sturmey Archer or a Sclumpf drive are the only options.
01-10-17, 08:16 AM
#34
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The cost is prohibitive for many folks, and special frame preparation and installation tools are required, so most bike shops are not equipped to install them.
I have installed a couple of them (I have the required tools), but with most inquiries I get, I usually talk them into better options.
So, they are kind of relegated to the "cost is no barrier" market which is sort of where I see the Pinion gear fitting in.
Here's a video featuring the bike with a Schlumpf paired with 2 speed kick back coaster brake.
I just noticed I erroneously said in the text on the video it is a high speed drive. It is just a speed drive.
01-10-17, 08:42 AM
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Yes there are shaft drive bikes still being built. A friend in the bike club has one. It is great for dirt roads and gravel grinding.
01-10-17, 09:54 AM
#36
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I like my MD for Bromptons, it's 3 speeds are used twice , 50t crank acts as if a 20t in low range..
01-10-17, 11:20 PM
#37
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