Chain wear checker for a Brommie.

[Kell]

As I say. I tried to get too much out of a previous chain and it left me physically and financially worse off.

An estimated three months off the bike at the current rate of £7 a day for the tube plus £9.40 for parking, five days a week. Is £328. That’s three and a half years’ worth of full drivetrain replacements.

 

[rogerzilla]

My rule of thumb for a derailleur bike is that one chainring should last three cassettes and nine chains, if the chain is changed in time (at 1/16" of extension per foot). But for a Brompton or anything with cheap sprockets, I'd run the chain twice as long and replace the sprocket at the same time. On fixies, some people run the whole lot into the ground as the chain won't slip or suck even if all the teeth look like shark fins.

 

[Yellow Saddle]

Most chain checkers don't work (they give a false positive). They can't distinguish wear that matters from clearance that doesn't. The Shimano and Pedro's ones are ok.

For a Brompton, I wouldn't bother. The sprockets are cheap so you can just run them into the ground and replace both at once. The chain has to be worn beyond 1/8" per foot to affect the chainring.

On a racing bike with a £150 cassette, you'd change the chain far more frequently.

1/16th per foot. Over that and you've exceeded the designed wear limit and it eats sprockets.

 

[Yellow Saddle]

Can someone perhaps post a photo of a Brompton (the one in question type) side-on view of the rear hub area. I want to understand something about these. I've never seen one in the flesh.

 

[rogerzilla]

1/16th per foot. Over that and you've exceeded the designed wear limit and it eats sprockets.

I agree for the sprockets but the chainring can cope with a more worn chain before it suffers unduly.

 

[Banjo]

Can someone perhaps post a photo of a Brompton (the one in question type) side-on view of the rear hub area. I want to understand something about these. I've never seen one in the flesh.

I will post some pictures but it will be later on today.

 

[Kell]

I think next time I do a full chain and sprocket change i’ll Just rotate the chainring so the teeth under load are not in the same place.

I was unsure if this could be done because of the reverse fixing on the crank, but looking at the one i’ve Just taken off, it’s doable.

(The rounded spoke is bottom left instead of top. This was just to check if it would fit back on the crank. Would probably need it to be a quarter turn. )

Would save £25.

 

[Banjo]

Not a great picture sorry.

 

[Yellow Saddle]

View attachment 486906 View attachment 486906
Not a great picture sorry.

Thanks, but that doesn't help.

90 degrees and in-line with the axle. Use the focus feature on your camera,

 

[Banjo]

Or use a real camera instead of the crappy one on my cheap phone.The stainless steel shoe thing to the right of the axle moves the guide wheel in or out shifting the chain onto the large or small sprocket.

 

[Yellow Saddle]

Thanks, that's good. One more thing. How many teeth on that sprocket?

 

[Banjo]

Thanks, that's good. One more thing. How many teeth on that sprocket?

My bike is the standard ML6 with 13 and 16 teeth sprockets. And a 50 tooth chainring.

You can order the bike with higher or lower gearing.

 

[Yellow Saddle]

My bike is the standard ML6 with 13 and 16 teeth sprockets. And a 50 tooth chainring.

You can order the bike with higher or lower gearing.

Thanks.

 

[mitchibob]

Even so, you can still get about three chains from a cassette before it needs replacement. I don't see the point in routinely replacing something.

But nothing like as close to the ground and picking up so much crap. The only time I tried to change chain without changing sprockets, the first time I went up a 1% gradient, the chain slipped on every turn of the cranks. Was the night before a sportive and ended up putting the old chain back on as I'd left it too late to find sprockets.

Sprockets are very cheap and quick to change.

 

[berlinonaut]

But nothing like as close to the ground and picking up so much crap.

I can highly recommend using a better (longer) mudflap than the stock one on the front wheel. With the stock one dirt and water gets thrown directly onto chainwheel and chain (as well as water onto your feet), with a longer one none of this happens any more. With drastic positive effects on chain life (as well as on the dryness of your feet when you ride in the rain). With readers of the German Bromptonauten-forum the "Fahrer Latz Race" is close to become a standard on the Brompton to the same amount as Ergon Grips are. Both are a drastic enhancement over the factory standard. Obviously it is easy to build a longer mudflap yourself from surplus materials - give it a try.