Replacing rear hub gear on bike

Doodee

Howdy all.


My girlfriends bike is a 3 speed rear hub. She really likes her bike but it has been out of commission for a number of years and the gears need replacing.
She has said that she brought it to a bike shop and that they can not fix it (middle gear is gone).

So I figured I would do her a solid and try to get it up and running for the summer months.
I know sfa about hub gears and am hoping it will be a simple case of take off previous gears and replace with shiny new ones.
From what I have read, the Shimano Nexus gears are fairly popular.

So what I am looking for is advice on what I will need and whats to know before embarking on that project.

All help with this is appreciated.
I've attached a pic of the current gears as they look.

penexpers

If the rear hub can't be repaired then you'll need to replace the hub which means: delacing the wheel, hoping the new hub has the same dimensions as the old hub (if it's not, you'll need new spokes too), then rebuilding the wheel. It's not an easy job, might be best left to a bike shop.

Bren10101

Wouldn't he just have to take the cassette off the hub, then pop a new one on?

cdaly_

What you're looking at is replacing one hub with another and rebuilding a wheel. You'll need to check if the current and replacement hubs have the same spoke flange diameter and width. If not you'll need different spokes. You'll also need to consider if the current spokes and rim are good enough to re-use or should you be replacing them too (ie a whole new wheel). Next, the new hub has a coaster brake fitted too. Is this the current setup or is there a separate rear brake? If separate, do you want to convert to coaster brake?

kona

Dont bother getting a hub and rebuilding the wheel, just order in a wheel with the internal gears already fitted. Shimano Nexus come in 3 and 8 speed, and sturmey archer do hubs aswell, rolhoff do them too but they are very pricey.

Make sure the shifters are compatible too.

Doodee

cdaly_ wrote: »

What you're looking at is replacing one hub with another and rebuilding a wheel. You'll need to check if the current and replacement hubs have the same spoke flange diameter and width. If not you'll need different spokes. You'll also need to consider if the current spokes and rim are good enough to re-use or should you be replacing them too (ie a whole new wheel). Next, the new hub has a coaster brake fitted too. Is this the current setup or is there a separate rear brake? If separate, do you want to convert to coaster brake?

There is only a front brake on the bike from what I can see, so it's possible it has a coaster.
Tbh, the bike itself was left sitting in a friends shed for some time before she brought it over so it might be worthwhile replacing the wheel now as I did see some rust.
Where's the best place to pick up a wheel with the internal gears already fitted?

[Edit] After looking at the pictures it appears to be a Sach (SRAM) S7 Spectro Hub. So a 7 Gear system and not 3.[/Edit]

seamus

Appears to be a Sachs Spectro S7 according to what's written on the hub in the photo.

That is indeed a coaster hub. Good news is that a direct replacement (without having to buy new shifters) is possible with the SRAM S7. Bad news is that the hub alone will cost you nearly €200

If that's the cost of the hub alone, I imagine you'll pay about €250 for a full wheel with the hub fitted. Fully built wheels with internal gears are rare enough online because there isn't the same demand for them. You may be better off getting a quote from a local shop.

Holyboy

Wooh! All this talk of replacing hubs and wheels is expensive,from the small screen on my phone it does indeed look like a Sachs/SRAM hub,these very rarely have problems with the internals 95% of the time the problem is with the shifter and/or click box or even just a slightly bent pushrod,but the good news is if the rest of the wheel isnt in too bad condition and it is the internals, parts are available and it can be serviced,worst case would be the whole internal unit would have to be replaced but its not a big job and I doubt it would come to that,but all that has to be done is take out the whole unit inside and slide in a new one,much easier than building or buying a new wheel.