Brompton chain sizing guide

Which chain do I need for my Brompton?

Over time chains and sprockets wear out. Due to the workhorse nature of the Brompton and the fact that the drivetrain is closer to the ground than on larger bikes (it picks up more dirt / grit) they can wear even quicker.

Choosing the correct chain for replacement can be confusing so we made this guide to help.

But first - if you are replacing the chain or rear sprocket(s) then we recommend replacing both parts the chain and the sprocket. We describe it as an old married couple - they get comfortable with each other and wear at about the same rate.

So remember - if you replace the chain alone then the chain may well slip - and the same if you replace just the chain. Check back for our next article on choosing the correct sprocket.

How many teeth does your chain ring have?

The first place to start is to count the number of teeth on the front chainring. Brompton supply them in 3 sizes: 44 teeth, 50 teeth and 54 teeth.

If your Brompton is a 3 speed or 6 speed then the chances are that this is a 50 tooth front ring (as that's the standard) - though it could have been changed to lower gearing (44T) or higher gearing (54T)

If your Brompton is a single or 2 speed version, then chances are it has 54 teeth (as that's the standard) - but again the gearing may have been lowered.

When you have made a note of this - count the number of sprockets (there should be one or two) and the number of teeth on the largest sprocket.

So which chain width?

Now you know the number of teeth on the front and rear - choosing the chain is quite easy!

Historically there used to be two widths of chain used by Brompton:

• 1/8 inch used on single sprocket bikes (1, 3 and 5 speed) - the part code ended in a W (for wide) such as QCHAIN100W

• 3/32 inch used on derailleur equipped bikes (2 and 6 speed) - the part code ended in DR (for derailleur) such as QCHAIN100DR

That gave us a total of seven chains to choose from

Since 2013 (we think that was the correct year), all new Bromptons have been equipped with the narrower 3/32 inch chain (which incidentally is easier to remove and install as it has a SRAM power link so no special chain tool is (normally) required.

So, we will assume you are going to replace the sprockets - you are going to aren't you? 

That reduces the number of chains to choose from to four - and which of the four depends upon the sprocket and front chain ring combination as shown in the table below.

The below list shows for each front chain ring size, based on the largest rear sprocket which Brompton chain is required:

44 Tooth Chainring
12t/13t/14t   - QCHAIN096DR (96 links)

16t/15t - QCHAIN098DR (98 links)

50 Tooth Chainring

12t/13t (3 speed default) / 14t - QCHAIN098DR

15t/16t (6 speed BWR default) - QCHAIN100DR

54 Tooth Chainring

12t (single speed default) / 13t / 14t - QCHAIN100DR

15t/16t (two speed default) - QCHAIN102DR

And there you have it - all you need to choose your new shiny chain.  Check back for part two - choosing the correct replacement sprocket.

Resources:
Brompton chain size document
Brilliant Bikes - Brompton chains

Brompton new colours for 2015

The New Year - 2015 sees some new frame colours supplied by Brompton

Black (the most popular colour) and white (collectively known as the mono range), remain the cheapest (there is a surcharge for the other colours)

Brompton Lime Green colour - new for 2015

2015 Brompton Colours

The new Brompton colours introduced are:
Berry Crush (shown below)
Cherry Blossom
Lagoon Blue
Tempest Blue (this was actually available in the past and has been re-introduced)
Lime Green (shown to the left here)
Ivory (this was available

As with previous years you can choose a bike in just one colour - or with the main frame in one colour, with the extremities (rear frame/triangle, handlebar stem and forks) in a second colour.

2014 Brompton Colour list

Some of the colours previously available have now been discontinued - but don't worry if you need to replace a broken part.

Brompton still supply frame parts for all colours that they have ever produced - even the old gloss paint finish.

There is however a slight price and possibly time penalty for the non-current colours, as they have to be painted specially.

Any replacement frame parts must be supplied and fitted by an authorised Brompton dealer - so no DIY replacements.

Brompton Cherry Crush - Another fruity new 2015 colour

The complete list of 2014 Brompton colours is as shown in the list below - those with a line through are no longer available on new 2015 bikes:
Black
White
Turkish Green
Claret
Cobalt Blue
Racing Green
Sage Green
Desert Sand
Hot Pink
Red
Orange
Yellow
Apple Green
Arctic Blue
Raw Lacquer

Titanium parts are still in short supply, meaning that it's difficult to get superlight Bromptons - though it is rumored that this could be rectified for good in 2016
 
External Resources:
Brompton Bicycle
Brompton spare parts and accessories at Brilliant Bikes

Brompton tyres

Brompton Tyre Options

We thought we'd give a quick run-through of the tyres available for your Brompton folding bike - if we've missed anything or got it wrong, or you just disagree - let us know! (There are other tyres available - we have just listed what we think are the most popular)

The Brompton folding bike uses a 16 inch tyre - but not all 16 inch tyres are the same (the 16 inch refers to the outside diameter - roughly). Some Moultons for example also use 16 inch tyres - but these can also be called 14 inch due to the internal diameter.

So how do I know the Brompton Tyre Size?

All Brompton folding bikes use the same tyre size

The best way to check that you are chosing the correct size is to use the ETRTO (European Tyre and Rim Trade Organisation) / ISO (International Standards Organisation) code.

Marathon plus tyres showing tyre size

This is normally imprinted in the rubber or sometimes printed on the side of the tyre as shown in the picture to the right.

In this case it is a Marathon Plus - it can be described as 16 x 1.35 or more accurately 35-349.

349 is the diameter of the shelf in the Brompton rim upon which the tyre bead needs to sit. So in theory all tyres with an ETRTO/ISO size of xx-349 will fit the Brompton - below is a list of the current standard Brompton tyres (fitted at the factory) and some alternatives.

Standard Brompton Tyre Options:

The following tyres are fitted as standard or an option when purchased from the Brompton factory (normally via your local dealer or a Brompton junction shop)

Brompton Schwalbe Marathon Racer tyre

Brompton Marathon Racer Tyre by Schwalbe 16 x 1 1/3 / 35-349
This is a tyre made by Schwalbe for Brompton - it's new for the 2018 model Brompton and available from December 2017

The Marathon racer will be the default / no extra cost option on Brompton bikes 2018 onwards

It's a directional tyre - so you will have to make sure you fit it the correct way around (there are markings on the tyre but they can be difficult to spot - you can also tell by looking at the tread pattern)

Brompton Marathon Tyre by Schwalbe 16 x 1.35 / 35-349
This is a standard tyre made by Schwalbe and (in our opinion) slightly tougher (more puncture resistant) than the standard Brompton tyre - though this comes at a slight weight penalty.

Schwalbe give it a puncture proof rating of 5/7 (yes you read right the rating is out of seven)
It is also e-bike ready

Brompton Kojak folding tyre 16 x 1 1/4 / 32-349
This is the lightest of the Brompton tyres available - and equivalent to a slick racing tyre you might use on a road bike.
Because it is slick and can be pumped up to a higher pressure it has a lower rolling resistance.
Weight is gained not just by having thinner / lighter rubber, but also with a folding kevlar tyre bead - meaning that the tyre can be folded for storage (for example to keep a spare in your desk drawer in work - just in case). This tyre replaced the Schwalbe Stelvio which was discontinued approx 2009.
Schwalbe puncture rating: 4/7

Brompton Kevlar Tyre 16 x 1 3/8 / 37-349
This is made specifically for Brompton and is the standard tyre included in the price. There used to be two variants, standard (which came with a yellow label) and kevlar (which came with a green label). It has a reflective sidewall to make you visible to other traffic - this tyre was discontinued in 2017

Alternative Brompton Tyre Options:

These are all the correct size for the Brompton, but are not supplied as direct factory fit options.

Schwalbe Marathon Plus 16 x 1.35 / 35-349
This is actually our best selling tyre and Schwalbe's flagship touring tyre - a lot of people (us included) don't like getting punctures. Schwalbe call this tyre "Unblattable" - German for Unflatable (although probably not an English word - you get the point - it doesn't puncture easily) - we have a sample in the shop with drawing pins stuck in it - which don't make it through to the inner tube.
Brompton say that due to the stiff side wall it doesn't cornet quite as well as the Marathon which is why it's not an option from them.
Note: The Marathon Plus tyres are directional - so fit them according to the "direction" arrow - check before fitting to save fitting twice!
Schwalbe puncture rating: 7/7 (this is why the scale was increased from 6 to 7 we think!)

Schwalbe Kojak with wire bead 16 x 1 1/4 / 32-349
This is the same as the Brompton Kojak tyre except that it has a wired bead - adding approx. 85g per tyre and doesn't have a reflective sidewall, so ideally you should use wheel reflectors.
Schwalbe puncture rating: 4/6

Schwalbe Winter studded tyre 16 x 1.2 / 30-349
Introduced for the 2014/2015 winter, Schwalbe bowed to popular demand and describe this as being made for the Brompton.
Studs in the tyre mean it gives more grip on icy roads while you can also ride it on dry / ice free roads. these tyres don't help in snow though!

What to Brilliant Bikes know about tyres for Bromptons? We have been selling spare parts and accessories (including tyres) online since 2009 and in our Chobham shop, as well as using them on our own Bromptons. We currently have all of the above tyres in stock and offer free UK delivery.

Our personal choice: Schwalbe Marathon Plus 16 inch (we don't like punctures!)

External resources:
Brompton tyres at Brilliant Bikes
Schwalbe

Christmas shopping versus riding

More accurate would be - we're out riding!

We're closed Sunday's - it's our ride day

But it's almost Christmas already - so also Christmas shopping day

So with the sun shining and not wanting to get stuck in a jam of angry shoppers and have no parking available, it's off to the train station.

Passing close to Swinley Forest and it's mountain bike trails (Martins Heron) didn't help get into the shopping mood - or the train gradually filling up with grumpy families (what is the optimum date for Christmas spirit, before the initial excitement turns it into a chore?)

Crowded shops, pushy salespeople and a seemingly smoke filled outside (how does that happened) led to a shorter than planned shop and a resolve to:

Get it done on the Internet 

Only after getting home ASAP and getting out for a ride in the sun!

What's the reason that train feels slower on the journey home - it's like a race by the sun - to see if it can set before ride time. Luckily (just in case the sun is the victor) the lights were put on charge the previous night - maybe sub-conscious planning!

The bikes can almost be heard calling as the train gets closer to home, station by station.

Cold, fresh winter air at sunset - enough said :-)

Traffic Jam on Chobham common!

Remember: Even when we're closed - we're open for online sales at brilliantbikes.co.uk

And Monday morning we'll be back in the shop packing and sending your parcels - so you too can avoid the shops.

Whats your Brompton gear ratio?

As of now, late 2014, Bromptons (from the factory) come in the following gearing configurations:

Brompton 54T chain ring

Single speed
12 tooth rear sprocket
54 tooth front chain ring

Two speed
12T/16T rear sprokets
54 tooth front chain ring

Three speed (Brompton standard ratio)
13T rear sprocket
50 tooth front chain ring

Six speed (Brompton wide ratio)
13T/16T rear sprockets
50 tooth front chain ring

They are all available in a reduced gearing version, by replacing the front chainring with a smaller one - giving approx 10% reduction (so 54 tooth is replaced with 50 tooth on the 1 and 2 speed models and the 50 tooth is replaced with 44 tooth on the 3 and 6 speed models)

However - there are more variations available - such as reducing from 54T to 44T on the 1 or 2 speed Brompton, or changing from 12T to 13T or 16T on the single speed (for example)

Brompton Gear Calculator

We are sometimes asked for the exact ratios (and to be honest we are not that scientific)

This website seems to do just the job

It allows you to select standard configurations and gives the gear inches that you will get.

It even takes into account the ratio change based on different tyres (unfortunately it's slightly out of date - so Schwalbe Marathons still show as 16 x 1 3/8 " where as in fact they are now the same size as Marathon Plus at 16 x 1.35)

But it will give a good idea of what would happen if you changed the hub and or chainring.

Have fun

Related resources:

Brompton gear calculator
Brompton spares and accessories from Brilliant Bikes

Hopping around the Christmas tree ....

We opened our Brilliant Bikes shop in Chobham in 2013 - just before Christmas.

We actually didn't want to sell "kids bikes" as generally - of course not all - that we had come across were heavy (sometimes too heavy for the child to pick up after falling off), and poor quality - and we want to encourage people to ride.

Heavy, poor built bikes for kids didn't sit well with us - if your first bike is a poor experience, then it's unlikely that you will continue as you grow (like those poor skiers who are taught by their "friends" taking them to the top of the scariest black run and told "you'll be OK!")

While we were in the progress of refurbishing the shop prior to opening, we were approached by Frog Bikes.

Our Frogs lined up by the Christmas Tree

Frog Bikes are a local company (to us), based in Englefield Green - they were also fed up with the poor quality, heavy bikes their children were almost expected to ride - so decided they could do better if they made their own (company and bike)

Their initial sales were online - with delivery to a local bike shop for building by the shop mechanic (again - the assembly should not be overlooked) and collection by the customer.

They persuaded us to take one and build / deliver.

We were hooked - they were good quality (they constantly improve the build / specification) so we decided that when we opened, we would indeed stock childrens bikes - in the form of Frog Lightweight Bikes)

Forwards one year (to now) and we try and keep a full display in our shop in Chobham.

Full display?

Frogs (the original - not the road bikes or Sky team special edition come in 5 colours):
Smaller sizes come in red, purple, orange and white (with spots)
Larger sizes replace the white spotty colour with black (for young adults)

We keep one of each size - so you can try for size (we don't sell by internet and ship in a box as we believe that you should pre-size to make sure it fits), and each colour (so that having found the right size you can choose your favourite)

We do show availability online at http://brilliantbikes.co.uk/125-frog-bikes

Useful links:
Brilliant Bikes
Frog Bikes

It's been a year already!

When we say it's been a year - that's a year since we opened our shop (it's been even longer since we posted on this blog - we've been busy) - Brilliant Bikes, in Chobham

We opened our physical shop last year - just in time for the Chobham Christmas Extravaganza in 2013 - late night opening to you and me.

Brilliant Bikes Chobham - complete with snowflakes!

Of course we had previously been selling tools, spares and accessories for bicycles (and specialising in spares and accessories for Brompton folding bikes - with the odd leftover used for making Christmas wreaths as shown in the bottom picture) since 2009 at http://brilliantbikes.co.uk

So this year we have a bit more stock, were a bit more prepared and ... have our Christmas snowflakes proudly on display.

This time last year we were selling complete bikes by Frog - lightweight childrens bikes, and Pashley - classic handmade British bikes.

In 2014 we have added complete bikes from Marin - the founders of modern day mountain biking, who now make a complete range of bikes from full suspension and hard-tail (a bike with no rear suspension) mountain bikes through hybrid (sometimes referred to as dual-sport as they can be used on and off road) as well as road and cyclocross bikes.

Happy Christmas from Brilliant Bikes

We also stock Intense - another Californian brand - who hand make performance mountain bikes including the Interlake MTB of the year - the Tracer 275c - full suspension and carbon!

We were lucky with the weather - a cold wintery (temperature - no snow) night with full moon.

Sweets were handed out to passing children (we weren't under any type of commission from the local dentists - but we will suggest that to them next year) and anyone else who wasn't already full from the mince-pies being handed out by half of the village shops in Chobham.

Thanks to everyone who visited and see you again next Christmas - if not before.

Useful Links:
Brilliant Bikes
Frog Bikes