sherlock123

Hi
I'm new to this forum. I just wanted some advice.

I have a old Brompton that I bought second hand 17-18 years ago, for commuting via public transport etc.
This didn't happen and I tended to use my other normal sized bike, so I have barely used it.

It's got the old 5 speed Stermey Archer hub fitted, with 50t and 13t front and rear gears, I worked out today the chain 1/8".

Recently I've started to using it and I've found a few problems.

1. I'm finding that in 1st gear (lowest), the gear is slipping when under load (i.e on hills). It's fine when the back wheel is lifted.
Is it likely to be a faulty gear in the hub? or could it be the adjustment is out and it's somehow it's sat between gears 1-2.

I've tried adjusting it before and today, (applying the brakes to get it go wrong), and it seemed better but I haven't had chance to try it whilst riding today.
If it's a faulty hub, i believe it's quite expensive to replace. (I am probably able to do it myself).

2. I've found the bike to be quite high geared, so I have been thinking about reducing the front gear from 50t to 44t. As mentioned it's 1/8" wide chain-set. As far as I can see Brompton gears are now all 3/32 wide".
Will these fit my bike seeing how old it is?
I'm assuming I would have to replace the front and rear gears, plus the chain?

My main priority, though, is to fix the hub problem and make the bike rideable.
Any assistance will be appreciated
thanks
Cheers

fietsbob

Sturmey archer hubs have been around a long time .. sought out manual reprints first ? or need other people to find links for you
No the 3 by 2 '6' speed uses 3/32"... 3 speed can stay 1/8" or buy a 3/32 cog both are made
. Sun Race Sturmey Archer moved production out of England .. Bankruptcy buy..


(I know most searches are directing you to buy stuff,, try https://hubstripping.wordpress.com/






...

fietsbob

I put the largest flat cog that fits on a S-A 3 spreed (a 15t , 16 - 21t is dished.. & 16 t hits the edge of the chainstay any how)






..

Bill Kapaun

Assuming you can get the hub problem fixed, a 15T rear cog would give nearly identical gearing. Equivalent to 43.3T.

sherlock123

Thanks for the replies. Apologies for the delay.
I followed some of the advise, i found the Sturmey Archer instructions etc. I didn't have time to take the hub apart, but I have got it working, maybe I will do that another time.
It's not perfect, gears between 2 and 3 don't always change gear straight away, but it's not slipping on the 1st gear anymore. I probably need to replace the gear cable as well.
The hub indicator chain was not screwed in properly and some indicator chain links were damaged or bent, so I've replaced it. The main chain also had some damaged links, which I replaced, but I'm waiting for a replacement chain to come. I have replaced the rear sprocket as suggested, from a 13t to a 15t. which has improved it.

Thanks again

Dan Burkhart 

I'm assuming from this that you have the hub with a single indicator chain. Earlier models had two. When you say it was not screwed in properly, I hope you did not assume it is meant to be screwed in tight. It must be backed off at least a half turn so the chain is free to align properly in the guide nut.

sherlock123

Yes it's a single chain indicator. Over the years it had unscrewed itself, maybe when the gear cable was adjusted, so the indicator was not in the right place.
I screwed it in then backed it off, as you say, so it was straight along the guide, but I've replaced it anyway.

Cheers

GamblerGORD53

My hub is the newer SA RD5w.
It had a sticky key flaw from the start. The 2 nubs that move in/ out of the sleeve in the pinion assembly that has 6 rows of 4 nubs.
I used an engraver to grind a hair off the last 6 mm of the opening, more right on the lip. I stripped off all the other parts to see what was going on when I pulled the shift chain. I got it so there is NO sticking in any of the 5 slots. I have done 1,600 miles since in 9 weeks. I LOVE this hub.

hatcher8

There is a great Youtube video on how to adjust the SA 5 speed. I am new to posting here and the system will not let me post the video url but just search the following and you should find it. Use exact spelling.

Sturmy-Archer Sprinter 5 speed hub
March 1st 2008