Brompton - upgrade to reduce wear and tear

[Ruffles]

Hi

I have a standard 4 year old Brompton (M3L?) and commute through London. I tend to ride it quite hard as it's my daily exercise which does rather wear bits out. No complaint about the Brompton - it's not a racing bike! And the parts are cheap.

I always use standard Brompton parts. I replace the chain and sprocket every four to six months by which time the chain has typically stretched by 1/8 to 3/16 inches / foot. This doesn't seem to be often enough as by then the stretched chain has already caused significant burring on the alloy chainring. It's not so much the cost (though this is significant as the ring and crank are integrated) it's the hassle!

Anyway, has anyone any suggestions as to how I can upgrade the transmission? My guess is that the chain is key here. Are the new 'spidered' chainsets any stronger.

I use a Giant Defy at the weekend for training and triathlons. No measurable chain stretch at all after a year and a half. But then it's supposed to be ridden hard. I am really abusing the Brompton. And doing a lot of stop - starts. I've replace the rear rim three times!

Ruffles

 

[Pale Rider]

Brompton transmissions are known to be one of the weaker points of the bike.

Conventional wisdom would be to replace the chain more often which should mean you shouldn't have to replace the sprocket/chainring every time.

What mileage are you doing each month?

 

[Ruffles]

Fit a different chain set. I got cranks from Spa Cycles for about £20 plus £15 for the chainring.

Part number. BB tapers are a pain. There are two sizes - both very close.

 

[Ruffles]

Brompton transmissions are known to be one of the weaker points of the bike.

Conventional wisdom would be to replace the chain more often which should mean you shouldn't have to replace the sprocket/chainring every time.

What mileage are you doing each month?

I think a new chain every four months should be enough!
I spend a little less than an hour per day on the bike. Mileage isn't terrible relevant in Central London. Strava reckons I average 15km/h with a peak of 60km/h!

 

[Ruffles]

Actually I think the truth has just dawned on me. The problem is simply that the standard chain isn't up to the stress of all those 'racing' starts at the traffic lights.
I've been buying the standard "Brompton 1/2" x 1/8" 98-link Chain - Plated".
Presumably my Defy has a more sophisticated chain (narrower?) to suit a 10 speed cassette. Would a narrow chain fit? I notice that Brompton are supplying narrower sprockets. The last two were very different - forged and plated rather than pressed.

 

[John the Monkey]

I switched to a KMC "Rustbuster" chain recently - it's dealing with the winter rather better than the Brompton branded chain did (so far).

I'd be interested in the chainset, if anyone has specifics/suggestions, as I reckon that will be the next part needing replacement on my B.

 

[srw]

*looks at Brompton*
*looks at chain*
*doesn't see a problem*
*suspects problem is in the mind of the OP*
*moves on*

Seriously, I've never worried about chain wear or chainset wear on a Brompton. I think my first one (5-day-a-week commute, almost no maintenance) lasted for about 8 years on two chainwheels and perhaps 3 chains. My current one (no maintenance other than chain lube) has so far lasted 5 years on one chainwheel and one chain.

 

[TheDoctor]

4 months from a chain? I've got 5 years on mine so far, and it didn't even occur to me to look at it before going touring for a week.

 

[GrumpyGregry]

The stock cranks made of cheese and the chainrings of plated cucumber.

The nice people at SJS will sell you everything you need to replace these nasty nasty pieces of parp. I went SA as part of my 8 speed conversion. Cheap heavy ugly strong.

 

[TheDoctor]

The stock cranks have done me fine for 5 years, and are they not made by Stronglight? The ST55 on my tourer looks identical, and I've been using that for 4 years.

 

[srw]

The thing about half-inch chains is that they're immensely strong and resistant to wear. Yes, they stretch, but with a hub gear that doesn't matter all that much.

The recommended approach to a stretched timing chain on one of Mr Thorn's Rohloff tandems is to adjust the eccentric BB until you can adjust no more, and then to remove a couple of links. Rinse, and repeat.

 

[GrumpyGregry]

This is the Achilles heel of the nasty Brompton stock chainset...

The chainring is swaged (is that the right word) to the crank, not bolted to it. Big rider, strong legs, wrong gear... rip, and they're walking home. And the same rider can make a chainring fold up. Not so handy on a folder as you might think.

EDIT: not my photo. I was too angry when mine went to take pictures.

 

[GrumpyGregry]

And you had ripped it all off and thown it away before you had calmed down?

Thrown the bike into the nearest Evans workshop the first time it happened, which was before I'd discovered the joy of cycling forums, and back to Brixton Cycles on the second Brommie.

I think it also happened to Titus?

 

[GrumpyGregry]

I am spotting a commonality.

It is definitely a "big strong boy" problem. Sylphs, racing snakes, nymphs and elfs will be immune.

 

[TheDoctor]

This is the Achilles heel of the nasty Brompton stock chainset...

The chainring is swaged (is that the right word) to the crank, not bolted to it. Big rider, strong legs, wrong gear... rip, and they're walking home. And the same rider can make a chainring fold up. Not so handy on a folder as you might think.

EDIT: not my photo. I was too angry when mine went to take pictures.

Ooh eck!! Yes, that does look like a bad day out...