Bicycle Mechanics - X-RF5, older ball-locking version, what is the purpose of 'Sun pinion spring'?

Technical question here, perhaps my brain is missing something; I'm looking over the manual for the x-rf5 and I can't see why there's a need for a spring between the two sun pinions. I'm wondering if it might be the cause of some of the inefficiency I experience with the hub. Surely a spring between the two pinions should have washers either side to reduce drag. . . but why is it there at all? I'll have to open up a hub sometime to get a clear look at this.

I'm not familiar with this 5s hub, but know other models, and can give some advice nonetheless.

First of all, manufacturers work hard to squeeze every penny out of production costs, so if there's a spring there, there's a reason.

It shouldn't affect efficiency in any case, since the sun in a planetary system is static, and keyed to the axle. The only way they usually move is to slide along the axle so either can engage a planet pinion while the other is disengaged. Basically the typical 2 sun system is 2 3-speed hubs occupying the same shell. One sun and it's planets produces 1, 3 & 5, while the other produces 2, 3 & 4.

The X-RF5 may have a different shift pattern and so may be organized differently, but the basic concept is the same.

Since the suns don't turn there's no reason to worry about friction.

I'm returning to this subject as I'm experimenting with the hub again. I've just been fiddling with the internals and the sun pinion spring does indeed cause quite a lot of friction, and I still can't see what useful function it serves. It happens to be the same part as the clutch sleeve spring, HSA478.

I plan to try installing the hub without it as some stage. . . with slight concern that I might have overlooked it's purpose and may damage the hub. But I have a spare, and I'm not happy with it's performance as is.

I have a nasty feeling that you'll trash the hub if you attempt to use it with the second spring missing, on my X-RD5 (admittedly, not the ball-locking version), it's the only thing that stops you potentially engaging both sets of gears at once and breaking something.

If your issue with the hub is that there's excessive friction in first and fifth gear, that's normal for SA 5-speeds. It gets better as the hub wears in.

I might have confused issues, are you referring to the sun pinion spring or the clutch sleeve spring, Airburst? My brain is tired.

I might have confused issues, are you referring to the sun pinion spring or the clutch sleeve spring, Airburst? My brain is tired.

Well, if yours works like my hub, the way it operates two different mechanisms (the standard 3-speed shifting system plus the mechanism that switches between sun gears) is using two springs of different stiffnesses to ensure that everything moves in the order it should when you pull the cable.

That spring is there to ensure the divots on the inner circumference of the sun gears align with the locking balls. Without it, the hub might sorata work, but the spring ensures positive coupling of the selected sun gear to the axle.

Aha. . . yes, that's the direction I was leaning in, it stabilises the positions of the sun pinions relative to the axle by buttressing them against their neighbouring parts, but in doing so introduces friction. However, it seems to me that they should be stable anyway since there's not much play between sun pinions and axle and they're held in place by their meshing with the planet pinions. I wonder if it's a sort of safety precaution in case there's a lack of lubricant between those parts.

as i read prior posts. mostly an "efficiency" obsession..

think Unicycle.. crank directly turns the wheel. doubt that can be improved on, for efficiency..


doing fine with the German 14 spd one, these days.
back in the not yet dead, Kennedy era,
The 3 by 3 , a cog cluster was an interesting addition to the old AW3..
my first 27 speed bike , 3 cubed.. triple crank too.

Well, I've done about 5 miles on a hub which has had the spring removed and all seems fine. Unfortunately the experiment is diluted by the fact that I converted from grease to oil (ATF) lubrication at the same time. I was expecting some improvement with the switch to oil but I wasn't expecting the sound of the pawls to almost disappear completely as it has done. I can still feel the grinding in some gears but the hub is nearly silent, which is quite remarkable. I was expecting a lot of oil leakage from the ball cage bearing area but there's been none whatsoever.
It seems to me that those who say these modern hubs don't run well on oil are mistaken, it's just necessary to seal the shell where the press fit join is and to put ptfe tape around the ball ring threads.

Well, I've done about 5 miles on a hub which has had the spring removed and all seems fine. Unfortunately the experiment is diluted by the fact that I converted from grease to oil (ATF) lubrication at the same time. I was expecting some improvement with the switch to oil but I wasn't expecting the sound of the pawls to almost disappear completely as it has done. I can still feel the grinding in some gears but the hub is nearly silent, which is quite remarkable. I was expecting a lot of oil leakage from the ball cage bearing area but there's been none whatsoever.
Did you dunk the internals in the ATF or just pour it in? I'm running a XRF8 on ATF, and it runs a lot quieter too. No leakage so far.
I'm going to be converting my XRF5 to ATF as well, so we can compare notes.
Did you grease the locking balls, or just let the oil do the job?
I was considering putting it together without the spring as well, but in the end I decided against it, and it is re-assembled, so I guess I'll let you be the test case.

Greasing the locking balls would be desirable but I'm not sure how long it'd stay there with oil moving around the hub. Perhaps it would as that section is quite well isolated. I didn't do it this time round but probably would next time.
I didn't really have the tools for a full-on dunking so I just added oil through the axle. I guess I'll probably add an oil port in the shell, though since nearly no oil seems to be escaping it's questionable how often I'd have to top it up anyway.

I tried sealing the shell join with some artists acrylic medium but it didn't work 100%. Next time I might try some "captain tolley's creeping crack sealant", it sounds like it'd be the right stuff for that job.

Another odd tweak I tried was to replace the locking balls with fractionally larger ones. The stock ones in my hub were something like 3.94mm and it looked to me as though they would sometimes jam slightly between axle and sun pinion (not really an issue if grease is holding them in place against the axle). So I switched them for 4mm bearings, which seem less prone to grinding.

The balls are just 5/32" bearing balls. I'll be interested to know how your tweak works out.

I've converted a second hub to synthetic ATF and it's running really nicely. I don't know much about the chemistry of lubricants: what type of grease do you think would be most suitable for the labyrinth seals in terms of it not mixing with the ATF and staying put?

I don't know that it matters much. I've just given a Shimano Alfine it's third annual ATF bath. It now has about 10,000 km on it, and I've been lubing the bearings with Shimano Nexus grease. The ATF does not seem to be breaking that down, as the bearings have all remained well greased every time I open it.
https://www.youtube.com/watch?v=oYBe3op7Pd8

Aha, those are your videos, I'd seen one of the Alfine ones before. Very helpful indeed.
I happen to have an alfine 8 that I've not installed yet. . . I gather you're a fan of the SRAM 7 speed though?

Aha, those are your videos, I'd seen one of the Alfine ones before. Very helpful indeed.
I happen to have an alfine 8 that I've not installed yet. . . I gather you're a fan of the SRAM 7 speed though?
I would be more of a fan if Sram bothered to provide support for the North American market, but they do not, so no, not really a fan.

Just to add to the discussion:

I have an S-RF5 (W) 2010ish hub that I love. It didn't work very well straight from the box. The cable adjustment was really finicky and didn't always engage the highest gears properly. After I removed the internals and gave them a good oil bath, the IGH runs beautifully. It was messy for the first few rides, but it makes a splendid winter hub.

I DID take it more or less completely apart once, but I'm trying to avoid that now. Too many parts to potentially lose or break. The whole unit dunk seems to work pretty well.

Anyone know if the hub bearings can be swapped out on the retainers easily?

The cone bearings on the drive side need to be the SA specific type as the retainer is different to generic ones, with a larger ID to allow the spring to pass through. I guess generic ones would be fine on the left hand side. I think that you'll damage the retainer if you try to swap the individual balls so if you want to put in high grade replacements then you'll probably have to ditch the retainer and assemble very carefully with grease to keep the bearings in place. You have to prise the dust caps off very carefully to get to the bearings. The ball ring bearings can easily be pulled out of the plastic retainer.

The cone bearings on the drive side need to be the SA specific type as the retainer is different to generic ones, with a larger ID to allow the spring to pass through. I guess generic ones would be fine on the left hand side. I think that you'll damage the retainer if you try to swap the individual balls so if you want to put in high grade replacements then you'll probably have to ditch the retainer and assemble very carefully with grease to keep the bearings in place. You have to prise the dust caps off very carefully to get to the bearings. The ball ring bearings can easily be pulled out of the plastic retainer.

How would you recommend servicing the bearings when they need to be replaced?

I'm not sure they do, particularly with oil. . . I've only been riding SA gear hubs 5 years but people run AWs for decades without changing bearings.

I had one cone race disintegrate but all other races on 3 hubs are immaculate.

How would you recommend servicing the bearings when they need to be replaced?

If you take decent care of your hubs, the question may well be not when but if they need to be replaced. Hub bearings should last something in the 25-50,000 mile range (maybe longer) which pretty high mileage for IGH hubs. IME, I've rarely seen a worn out cone, and never any other bearing wear on British built SA hubs, but I can't speak for the current stuff coming out of Taiwan.

If you do wear out a cone, but the balls in the retainers look OK, you might keep using them (the cones wear faster than the balls). OTOH if rust or other unusal wear has you needing to replace more, you need to source the original retainer, or carefully reload yours (can be done with some, but not all) or load loose balls using grease to keep them home until the cone is adjusted.

If you take decent care of your hubs, the question may well be not when but if they need to be replaced. Hub bearings should last something in the 25-50,000 mile range (maybe longer) which pretty high mileage for IGH hubs. IME, I've rarely seen a worn out cone, and never any other bearing wear on British built SA hubs, but I can't speak for the current stuff coming out of Taiwan.

If you do wear out a cone, but the balls in the retainers look OK, you might keep using them (the cones wear faster than the balls). OTOH if rust or other unusal wear has you needing to replace more, you need to source the original retainer, or carefully reload yours (can be done with some, but not all) or load loose balls using grease to keep them home until the cone is adjusted.

I see. I got into the habit of changing out my bearings whenever I repacked my hubs in traditional wheels (every 2000-4000 miles, depending on conditions). Just to clarify, I gave the internals an oil bath, but I greased the bearings. Should the bearings at least be regreased similar to other cup and cone bearings?

Should the bearings at least be regreased similar to other cup and cone bearings?

Different hub makers differ about this. Some say no grease, just the same oil as for the internals, and others say grease for the ball bearings, oil for the internals.

I've always used grease on the ball bearings, regardless of maker instructions. Realistically either a decent oil or grase will give adequate lubrication. I jsut prefer grease because it tolerates weather better, and has a longer service interval.

BTW- on UK built SA hubs, I've rarely, if ever, opened the hub for any kind of service. I just added a few drops of oil when it seemed like a good idea, and when I got nervous about the ball bearings (2-3 winters out) I'd service them from either end without touching the internals.

I don't know if the current crop of hubs is as bombproof as the older ones were, but I suspect that many owners are doing much more service than is really needed.

Different hub makers differ about this. Some say no grease, just the same oil as for the internals, and others say grease for the ball bearings, oil for the internals.

I've always used grease on the ball bearings, regardless of maker instructions. Realistically either a decent oil or grase will give adequate lubrication. I jsut prefer grease because it tolerates weather better, and has a longer service interval.

BTW- on UK built SA hubs, I've rarely, if ever, opened the hub for any kind of service. I just added a few drops of oil when it seemed like a good idea, and when I got nervous about the ball bearings (2-3 winters out) I'd service them from either end without touching the internals.

I don't know if the current crop of hubs is as bombproof as the older ones were, but I suspect that many owners are doing much more service than is really needed.
You're right about that, particularly as it pertains to hubs not ridden extensively in adverse conditions. My XRF5 had a good 7 years on it, winters included before I opened it up, and it would have continued on much longer without disturbing it.

I write this merely to express my. . . jubilation I suppose, my second 5 speed which was always better-behaved than the first I converted to oil is now running amazingly. During this evening's ride it's been near-silent in all gears, there's no real difference felt in 1st and 5th which are typically much less efficient than the middle gears. After 4 years of tinkering with these hubs but sticking to grease as lube I was on the verge of abandoning them but now it seems they're finally doing what I thought they ought to based on the design, that is, providing efficiency lose to a 3 speed but with a decently-spaced range of gears for city riding. I hope the seals keep up. . . so far there's zero leakage.
Whenever I've opened them up in the past it's seemed that the SA grease had stayed in the important places, particularly the pinions, but I think there's some areas that it inevitably gets forced out of. Often I found that the first 20 minutes of riding was perfectly smooth but very quickly some grinding resumed. Not so with oil.

My original plan was that if oil proved successful I'd install an oil port/'lubricator'. Now I'm not sure if that's necessary since no oil is being lost and it doesn't look like I'll need to top up often. It'd still be convenient to have an oil port but I'd read that they have a tendency to leak and they don't seem readily available in the UK, so perhaps it's better to do without one.

I write this merely to express my. . . jubilation I suppose, my second 5 speed which was always better-behaved than the first I converted to oil is now running amazingly. During this evening's ride it's been near-silent in all gears, there's no real difference felt in 1st and 5th which are typically much less efficient than the middle gears. After 4 years of tinkering with these hubs but sticking to grease as lube I was on the verge of abandoning them but now it seems they're finally doing what I thought they ought to based on the design, that is, providing efficiency lose to a 3 speed but with a decently-spaced range of gears for city riding. I hope the seals keep up. . . so far there's zero leakage.
Whenever I've opened them up in the past it's seemed that the SA grease had stayed in the important places, particularly the pinions, but I think there's some areas that it inevitably gets forced out of. Often I found that the first 20 minutes of riding was perfectly smooth but very quickly some grinding resumed. Not so with oil.

My original plan was that if oil proved successful I'd install an oil port/'lubricator'. Now I'm not sure if that's necessary since no oil is being lost and it doesn't look like I'll need to top up often. It'd still be convenient to have an oil port but I'd read that they have a tendency to leak and they don't seem readily available in the UK, so perhaps it's better to do without one.
Glad to hear it's working for you.
Actually, you have an oil port without drilling one. Just take out the indicator and add oil through the axle whenever you feel the need.
But if it's well oiled, and you don't see any leakage,it shouldn't need much topping up. It doesn't need much.