Technical Q: DT Swiss star ratchets - Why are both sides sprung?
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A bit of an information-rich technical question here, but maybe one of you has an answer.
The DT Swiss (and DT/Hugi) hubs have star ratchets (the serrated ring-shaped things that engage each other on their axial faces). In principle, only one side of a star ratchet assembly needs to be sprung and movable, but on the DT Swiss hubs, both sides are sprung and can slide within their splines.
Here is a picture of the DT Swiss style hub, with the cassette body slid off slightly, to show you what I mean.
I am curious about reasons why the DT hubs are like this. I was thinking it might be a sort of insurance against one side getting temporarily stuck, in which case the other side would take up the slack and would keep smacking against the stuck side and possibly help free it up. Or maybe the spring works best with a short stroke, so splitting the total movement among two springs might help. Or maybe the splines work better on a short stroke, and again splitting the movement between two splines helps things.
The Chris King and some Shimano freehubs also have star ratchets, only with one side sprung and mobile, but interestingly they also have a helicoidal spline that drives the two star ratchets together under pedaling force.
Backstory of why I'm thinking about this: I have a line on a vintage superlight Hi-E cassette hub, which Jobst Brandt says has a problem with the star ratchet slipping, possibly due to poor engagement (don't try to talk me out of it, it's just for fun on an otherwise-ridiculous period-correct superlight fetish bike). These star ratchets are aluminum, which is worrisome because of galling and low hardness and toughness, and are only sprung on one side. The ratchet teeth have a lot of rake, which might help drive them together under pedaling force, but it's unclear how well this might work. I'm thinking about what I might do to upgrade the thing if it breaks, considering I have a machine shop at my disposal. Best idea I've come up with is to retrofit DT Swiss star ratchets (and maybe the whole cassette body), but it's of course easier with only one side sprung, which is not the way they designed them.
The DT Swiss (and DT/Hugi) hubs have star ratchets (the serrated ring-shaped things that engage each other on their axial faces). In principle, only one side of a star ratchet assembly needs to be sprung and movable, but on the DT Swiss hubs, both sides are sprung and can slide within their splines.
Here is a picture of the DT Swiss style hub, with the cassette body slid off slightly, to show you what I mean.
I am curious about reasons why the DT hubs are like this. I was thinking it might be a sort of insurance against one side getting temporarily stuck, in which case the other side would take up the slack and would keep smacking against the stuck side and possibly help free it up. Or maybe the spring works best with a short stroke, so splitting the total movement among two springs might help. Or maybe the splines work better on a short stroke, and again splitting the movement between two splines helps things.
The Chris King and some Shimano freehubs also have star ratchets, only with one side sprung and mobile, but interestingly they also have a helicoidal spline that drives the two star ratchets together under pedaling force.
Backstory of why I'm thinking about this: I have a line on a vintage superlight Hi-E cassette hub, which Jobst Brandt says has a problem with the star ratchet slipping, possibly due to poor engagement (don't try to talk me out of it, it's just for fun on an otherwise-ridiculous period-correct superlight fetish bike). These star ratchets are aluminum, which is worrisome because of galling and low hardness and toughness, and are only sprung on one side. The ratchet teeth have a lot of rake, which might help drive them together under pedaling force, but it's unclear how well this might work. I'm thinking about what I might do to upgrade the thing if it breaks, considering I have a machine shop at my disposal. Best idea I've come up with is to retrofit DT Swiss star ratchets (and maybe the whole cassette body), but it's of course easier with only one side sprung, which is not the way they designed them.