# Brompton - upgrade to reduce wear and tear



## Ruffles (24 Nov 2014)

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


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## Pale Rider (24 Nov 2014)

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?


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## Ruffles (24 Nov 2014)

User said:


> 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.


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## Ruffles (24 Nov 2014)

Pale Rider said:


> 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!


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## Ruffles (24 Nov 2014)

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.


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## John the Monkey (26 Nov 2014)

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.


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## srw (26 Nov 2014)

*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.


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## TheDoctor (26 Nov 2014)

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.


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## GrumpyGregry (26 Nov 2014)

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.


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## TheDoctor (26 Nov 2014)

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.


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## srw (27 Nov 2014)

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.


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## GrumpyGregry (27 Nov 2014)

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.


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## GrumpyGregry (27 Nov 2014)

User said:


> 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?


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## GrumpyGregry (27 Nov 2014)

User said:


> I am spotting a commonality.


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


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## TheDoctor (27 Nov 2014)

GrumpyGregry said:


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



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


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## srw (27 Nov 2014)

GrumpyGregry said:


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


I'mm certainly big, and think I'm _reasonably_ strong - certainly strong enough to have contributed to more than one Rohloff tandem flange failure.

I simply haven't had a problem wiith a Brompton.


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## GrumpyGregry (27 Nov 2014)

srw said:


> I'mm certainly big, and think I'm _reasonably_ strong - certainly strong enough to have contributed to more than one Rohloff tandem flange failure.
> 
> I simply haven't had a problem wiith a Brompton.


Suspect it is a QC issue. As I know one dainty lady who had hers go....


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## Ruffles (15 Apr 2016)

Yes I know it was an age ago but here's an update for those interested.

I ended up replacing the chainset with the same integrated Brompton unit. It wore quickly as before - teeth visibly asymmetric - and consequent accelerated chain wear. You could 'feel' the teeth when riding hard.

So last Christmas (2015) I got round to replacing the BB and fitting the newer 'spidered' chainset. Some months later I can detect no chain wear and it 'feels' smooth like a racing bike. So I think it's probably worth the expense and hassle.

Hassle? Well I ended up drilling out the plastic BB breaking drills in the process all because there was no grease on the thread.
I also bought new rim and bearings to refurbish the rear wheel only to discover that the bearing surface in the hub shell was hideously scored. Cheaper to buy a new wheel. (Anyone want a brand new old style rim?) So ended up shelling out > £400 in all.


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## John the Monkey (15 Apr 2016)

The "like", incidentally is not for your tribulations, @Ruffles, but for being so kind as to share them and your solutions. Brompton chainset change is a job I have planned for the summer, hopefully to the new spider chainset too.


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## 12boy (18 Apr 2016)

I think Brompton chains wear out more quickly than do my 700 c bikes' but they obviously have the chain higher off the ground and being single or IGH don't have a chain tensioner to get dirty either. In maybe 5k miles I have gone through a number of chains and one cog, although I use both a single speed ( the cog that wore out) and an SA 3 speed that hasn't yet. Cogs here are , I think, 8 bucks plus shipping so I buy a couple at a time. I wax the chains and try to keep them well lubed. I am clear the tensioner is needed for the fold but it does seem to be a dirt magnet. I have repacked the front hub a couple of times , which is easy to do, and the single speed breaks down to clean and lube the freewheel better than any other wheel I've owned. I had replaced the bottom bracket with a 119 vuelta BB for $13 and it has held up fine. I hated the plastic tightening rings on the original. I have used a Sugino RD crank with a vuelta chain ring but one tooth got chipped and I went back to the original swaged one which has held up fine and is really light. Are the newer 2 piece cranks as light as the swaged?


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## Kell (19 Apr 2016)

I stripped down and cleaned my drivetrain for the first time since getting my bike last August. The amount of caked on sludge was shocking. The two cogs on the derailleur/tensioner wouldn't come clean with just degreaser and a gear brush. I had to use a screwdriver to scrape the sludge off.

I guess being that much closer to the ground is going to take its toll.

The sludge is nasty stuff though, I did it a week and a half ago and I think it's only the fact that I've shed a layer of skin since then that my fingers are now clean. I tried Swarfega, scrubbing brushes, Citrus degreaser and even a metal pot scourer, but the sludge was ingrained in my fingerprints and wouldn't come out.


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## srw (19 Apr 2016)

User said:


> Some people buy a second tensioner so that one can be soaked in degreaser and finished off in the dishwasher, while the other is in use.


Some people care too much about cosmetic cleanliness.


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## 12boy (20 Apr 2016)

I may look into sealed bearing pulleys. When you lube your chain with the wax bath method the wax is much cleaner than oil. Sticks better in wet/snowy conditions. I have never put a bike part in the dishwasher...my wife would not bless that endeavor. I do have a for-that-purpose crockpot for the chain waxing though and another with strong detergent/water would be good to soak nasty parts in.


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