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My dumb question about geared hubs

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  • UPD
    replied
    Originally posted by tholub View Post
    A geared-up 24 would be better than a geared-down 36 in every conceivable scenario.
    I agree. It's useless to have a ton of spinning on a 36er. There's plenty of leverage for climbing from using 165 or 150mm.

    Leave a comment:


  • tholub
    replied
    Originally posted by Up Rite View Post
    I see a few others here would go for a geared down hub.

    So how would a 24" with current gearing up be compared to a 36" geared down in various situations?
    A geared-up 24 would be better than a geared-down 36 in every conceivable scenario.

    Leave a comment:


  • bouin-bouin
    replied
    Originally posted by UniDreamerFR View Post
    @Didier (Bouin-bouin) Since it's been your goal for all those years (on your signature), and since it looks like you have all the 3D work done (do you?), why don't you just make a prototype of it to see how it behaves and what must be modified and so on?

    Is it because you don't have the tools to make it, or the budget to make some parts (or all parts) made by a professional, a lack of time or is the 3D work just not complete yet, and in this last case, what are the remaining issues?
    About 1/3 of the parts have been designed under CATIA V5 with strong support of Martin Charrier who is less available because preparing is PHD, me too; other points should be OK

    Leave a comment:


  • UniDreamerFR
    replied
    Originally posted by Bouin-bouin
    Still under 3D design but no recent progress
    It has been presented somewhere in this forum, Greg Harper made some comments at this time. I had long discussion with Florian at Brixen Unicon and he confirmed the right concept
    Hier 18h33
    @Didier (Bouin-bouin) Since it's been your goal for all those years (on your signature), and since it looks like you have all the 3D work done (do you?), why don't you just make a prototype of it to see how it behaves and what must be modified and so on?

    Is it because you don't have the tools to make it, or the budget to make some parts (or all parts) made by a professional, a lack of time or is the 3D work just not complete yet, and in this last case, what are the remaining issues?

    Leave a comment:


  • bouin-bouin
    replied
    Originally posted by LargeEddie View Post
    They might be hard to find if you haven't seen them already and don't know what to search for, but there have been a number of discussions about why they are as they are and what other ways they might be. Certain forum members have argued with great passion for downgearing.

    E.g.:
    http://www.unicyclist.com/forums/showthread.php?t=95916
    http://www.unicyclist.com/forums/showthread.php?t=99913

    Not an owner of one myself but my Occam's Razor answer would be that the Schlumpf hub is what it is because that's what Florian himself wanted when he designed it. It was a labor of love, not an answer to consumer demands.
    Thank you LargeEddie, my concept was detailed here : http://www.unicyclist.com/forums/sho...t=99913&page=2

    Leave a comment:


  • Up Rite
    replied
    The search function does not always yield what I seek.

    Leave a comment:


  • LargeEddie
    replied
    Originally posted by Up Rite View Post
    Instead of a gearing up from 1:1, why not have it on a larger wheel 1:1 and 1: 0.65?
    They might be hard to find if you haven't seen them already and don't know what to search for, but there have been a number of discussions about why they are as they are and what other ways they might be. Certain forum members have argued with great passion for downgearing.

    E.g.:
    http://www.unicyclist.com/forums/showthread.php?t=95916
    http://www.unicyclist.com/forums/showthread.php?t=99913

    Not an owner of one myself but my Occam's Razor answer would be that the Schlumpf hub is what it is because that's what Florian himself wanted when he designed it. It was a labor of love, not an answer to consumer demands.

    Leave a comment:


  • Vogelfrei80
    replied
    Originally posted by Mikefule View Post
    I think a small number of close ratio fixed 3 speed hubs were made, probably back in the 1950s or thereabouts. At one time they had quote an extensive range. I remember when the derailleur "5 speed" was an exciting new idea. Before that, the choice was single speed or Sturmey Archer - at least for ordinary people wanting bikes for normal use.

    However, Wikipedia shows that they reintroduced a 3 speed fixed hub in 2009:

    <<Three-speed fixed gear hub[edit]
    In 2009 Sunrace Sturmey-Archer re-introduced a three-speed fixed gear hub, the S3X.[11] This gives ratios of 100/75/62.5 (i.e. the top gear is direct drive and the others are geared down from it) and the internals are based on the newest five-speed freewheel hub (in the same way as the original fixed ASC was based on the contemporary FC four-speed hub).>>

    193 (193 GBP) https://www.bicyclehero.com/gb/sturm...SABEgKOKfD_BwE

    https://en.wikipedia.org/wiki/Sturme...fixed_gear_hub
    Already know about that but as I said before it has a splined driver only on the right side! My crancks are not connected each other directly. They use 2 chains each per side to drive the hub
    IF ANYONE KNOWS A FIXED GEARED HUB DRIVEN BY BOTH SIDE I'LL BUY IT AND TEST IT FOR YOU. ...I'm gonna open a new thread

    Leave a comment:


  • bouin-bouin
    replied
    Originally posted by pierrox View Post
    Bouin-bouin has been developing a geared hub for a while, though I haven't heard any news lately. His idea was to do that indeed: a lower gear, a 1:1 and a high gear. With the idea to have it in a 36" wheel.

    Still under 3D design but no recent progress
    It has been presented somewhere in this forum, Greg Harper made some comments at this time. I had long discussion with Florian at Brixen Unicon and he confirmed the right concept

    Leave a comment:


  • Up Rite
    replied
    I see a few others here would go for a geared down hub.

    So how would a 24" with current gearing up be compared to a 36" geared down in various situations?

    I would like to see if Schlumpf or someone else can come up with a 3 speed hub with direct, fast and low gearing, the shifting being done by grabbing a lever under the seat instead of clicking the heals.

    That would add a lot of potential options for unicycling.

    Leave a comment:


  • harper
    replied
    Originally posted by Mikefule View Post
    Although, as you will see upthread, they also made "fixed" versions which did have to cope with torque in both directions. Point is not that the production model would be suitable for a unicycle, but that the concept is theoretically possible.
    I'm sure we're on the same page, Mike. I know that S-A made fixed 3-speed and a fixed 2-speed hubs. I don't know if they were used widely or if they were successful or mechanically reliable. The freewheeling S-A bicycle hubs were wildly successful and popular. I do know that the backlash exhibited by multi-speed, fixed-gear epicyclic hubs is unacceptable for use on a unicycle whereas it would not even be an inconvenience on a bicycle. I will concede that reduced gear epicyclic hubs for unicycles are theoretically possible but I also know what the engineering gymnastics are that are required to realize it.
    Last edited by harper; 2017-11-26, 05:28 PM.

    Leave a comment:


  • Mikefule
    replied
    Originally posted by harper View Post
    The Sturmey Archer (not a unicycle hub) had the tremendous advantages of being chain-driven and requiring no reverse torque limit. It also didn't need to have a stout drive shaft running right through the center of the mechanism. This provides a lot of flexibility in the gear connection order.
    Although, as you will see upthread, they also made "fixed" versions which did have to cope with torque in both directions. Point is not that the production model would be suitable for a unicycle, but that the concept is theoretically possible.

    Leave a comment:


  • harper
    replied
    Originally posted by Mikefule View Post
    The Sturmey Archer 3 speed had one set of sun and planet gears, and a sliding clutch to choose the input and output. That gave you direct drive in 2nd, with (direct plus a third) in 3rd and (direct minus a quarter) in 1st.
    The Sturmey Archer (not a unicycle hub) had the tremendous advantages of being chain-driven and requiring no reverse torque limit. It also didn't need to have a stout drive shaft running right through the center of the mechanism. This provides a lot of flexibility in the gear connection order.

    Leave a comment:


  • Mikefule
    replied
    Originally posted by Vogelfrei80 View Post
    I tought about using it on my huni-rex: low gear about 31" virtual; direct drive 42"' virtual; high gear 56". But I cannot find a way to use sprocket on the left side of the hub. Left side hub spins geared while the sprocket on the right goes direct. Do you know if ever existed a geared fixed hub useful for a double chain giraffe or a huni-rex?
    I think a small number of close ratio fixed 3 speed hubs were made, probably back in the 1950s or thereabouts. At one time they had quote an extensive range. I remember when the derailleur "5 speed" was an exciting new idea. Before that, the choice was single speed or Sturmey Archer - at least for ordinary people wanting bikes for normal use.

    However, Wikipedia shows that they reintroduced a 3 speed fixed hub in 2009:

    <<Three-speed fixed gear hub[edit]
    In 2009 Sunrace Sturmey-Archer re-introduced a three-speed fixed gear hub, the S3X.[11] This gives ratios of 100/75/62.5 (i.e. the top gear is direct drive and the others are geared down from it) and the internals are based on the newest five-speed freewheel hub (in the same way as the original fixed ASC was based on the contemporary FC four-speed hub).>>

    193 (193 GBP) https://www.bicyclehero.com/gb/sturm...SABEgKOKfD_BwE

    https://en.wikipedia.org/wiki/Sturme...fixed_gear_hub

    Leave a comment:


  • Kitibob
    replied
    Originally posted by Vogelfrei80 View Post
    I tought about using it on my huni-rex: low gear about 31" virtual; direct drive 42"' virtual; high gear 56". But I cannot find a way to use sprocket on the left side of the hub. Left side hub spins geared while the sprocket on the right goes direct. Do you know if ever existed a geared fixed hub useful for a double chain giraffe or a huni-rex?
    I'm not sure I fully understand but I did some drawings of a setup which would have 2 gears: 1:1 and then another higher gear with a jackshaft - but i've left them at home.

    Leave a comment:

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