whoops there goes my chainring - replacement options

[T4tomo]

Last night I managed to shear off the chainring from the crank arm on my 2005 Brompton. Awesome leg power or some would say its a known issue point of weakness.

I was looking to possibly swap it anyway as I run 54 -13 on a 3 speed which was great when commute was pretty flat buty having moved to half way up a steep hill its a bit punchy so was looking at a 50T chainring anyway.

All I'm seeing online is 3/32 chainrings vs 1/8th that I currently have. Have I missed something or does a 1/8 chain run fine on 3/32 or do I need to change chain and rear sprocket all to 3/32s?

Also how long does a bottom bracket generally last - should I be looking to swap out given its 8 years old?

Or do I convert to 8 speed?

 

[BrianEvesham]

No idea, but kudos for the leg power!

 

[T4tomo]

I'll take the Kudos!

Just setiing off into the big junction at Bank of England - great place for it to happen. managed to get to pavement and hail a cab without incident. a bit of googling and i don't think i'm the first - the 2012 models have a modified design and stonger design I think

 

[Brommyboy]

I have an idea that the Brompton chain rings (except for the 46T fitted to the C version) are all 3/32" anyway. The 1/8" chain will run on a 3/32" chain ring, but, if you particularly want a 1/8" chain ring, then look up the Spa Cycles listing for track chain rings as a 1/8" is available. You will need the appropriate crank to go with it.

 

[T4tomo]

Cheers - yes I gather from another source that they are all 3/32nds now and run with 1/8 chain fine. Good to have it confirmed by you. So I have a 50T on order and crank tool coming too. Be interesting to see how it is going from 54 to 50T.

 

[Brommyboy]

You will be gearing the Brompton about 8% lower, which is about half a gear down in use. I find the gears too high generally as there is no difficulty in descending, only in ascending hills!

 

[T4tomo]

Well got the replacement parts thru and a crank puller so got it swapped over last night. According to manuals should have shortened chain to 98 links (from 100) but tensioner is taking up the slack so I think I leave as is rather than create potential weakness from popping a pin in and out.

Definately easier up the hills with a 50T than the 54t. Can cruise up slight slopes in top and still have 2 and 1 when the gradient increases. Happy to trade that for spinning a bit down hill