Monthly Archives: February 2013

Riding weight

Bike weight is a funny subject. Depending on the bike & use some people become obsessive about losing weight – although usually only on the bike? For a Brompton bike the expectation of it being a featherweight bike is probably unreasonable, considering its likely use & owner’s budget. Sure, I’ve seen some pretty light Bromptons but I couldn’t justify their cost & the trimmed-down specs wouldn’t suit my riding territories.

Another funny thing is the Brompton website giving you the chance to know the complete weight of your Brompton & accessories; you just add up the weights of everything you’re including. That’s unusual for a bike manufacturer; for other bikes the weight is some vague figure stated for one sized bike in the range & once you change the specs then you’ll only know the weight after you weigh your new purchase. (Of course, for buying lightweight components you need to remember the old saying, “light, strong & cheap: pick any two”)

Having said that Brompton list all their weights, things get complicated once you move to non-standard items. When I picked up (literally) Ralph from an eBay purchase, I really noticed the lighter weight over Robinson, my P6R. This was a surprise because Ralph has an Shimano Alfine 11-speed rear hub (& associated changes) & I thought I was going to suffer a weight penalty? Weighing the bikes showed that I wasn’t mistaken & Ralph really was about 1.5 kgs lighter. However, the good news was not to last…

Ralph needed a little TLC & I preferred some swapping or upgrading of components (eg my Brooks saddle moved from Robinson to Ralph & some Ergon grips went onto Ralph). A set of mudguards then went onto Ralph & both Bromptons were now in a similar riding state (both comfortable & ready for similar weather conditions). Lately the Bidon cages & on-board tools have been sorted out; all things that play hell (in small ways) with the bike weights but go together to make my Bromptons more ridable & useful – hence this blog title of “Riding weight”, rather than “Bike weight”.

Oh, & one last thing: I weighed my Bromptons in their new configurations & was once again surprised – this time the weights were identical. Ralph & Robinson now both weigh 12.8 kgs each. No featherweights but nice little bikes.


On-board tools

I’m not the sort of person to go riding without the basics that will allow me to fix a flat tyre. Bit of a security blanket I suppose, even though Bromptons are ideally placed to be folded & carried home in any form of public transport, if the Brompton (or me) runs into trouble.

My idea of the basics is a spare tube, tyre levers & pump. With most Bromptons having bolt-on wheels, a wheel spanner also needs to be included. The conundrum is where to carry everything & my C bag has been my place of storage (along with my water bottle). Now that my Bromptons are equipped with bidon cages, I decided to prepare for a “bag-less” ride & carry the tools on-board.

Brompton have produced a neat little toolkit that fits into the front section of the main frame but so far in the few months since release, I’ve been unable to obtain one – & now I believe they’ve been withdrawn to address a “quality issue”? My alternative is to rubber-band a cut-down wheel spanner, tyre levers & a small set of Allen keys together & wrap them in a set of disposable latex gloves. This fits cosily into the front section of the main frame.

A spare Schwalbe SV4 tube (Presta valve type) fits into the rear section of the main frame. My method of insertion is to double the tube over, lightly twist it into a spiral & then wrap this with a piece of fibreglass insect screen mesh (about 45cm by 20cm). This mesh “tube” then slides into the frame with far less friction than the tube alone. The length of the mesh fills the tube space & is easy to pull out.

The Brompton Zefal pump is fitted to the rear frame of one Brompton with a Velcro strap (hopefully) giving extra security. My other Brompton has a small pocket pump (Bontrager Air Pocket) fitted into the seatpost tube & secured by the seatpost buffer. (The pump is fitted into a length of inner tube (cut from an old Mountain bike tube) to prevent it from rattling.)

I’ve always been wary of the Brompton pump staying in place & preferred to carry the pump in the C bag. Now with my Bromptons carrying their tools on-board, I’m trying the Brompton pump attached to the rear frame but for peace of mind, will probably soon use pumps housed within the seatpost tube on both Bromptons.


Bidon cages

Bromptons have many unique features but one that I don’t like is the lack of a bidon cage mount. Carrying water on a ride in this part of the world is pretty essential.

My Brompton C bag rear pockets are a workable solution for a bidon holder but I prefer a cage for my bidon. Searching the Internet has yet to identify a cage mount that I’d be happy to use & I even have doubts about the rumoured Brompton magnetic water bottle. Many times I’ve returned to the question of how to mount a cage on my Bromptons & all I resolved is that a cage needs to be behind the stem, not impede the fold & be easily removable. And then, a new thought…

(a quick shop for some O-rings, various attempts with some Aluminium strip, add some foam to protect the stem paintwork, bolt on a cage, voila!)

Ralph (see pic) & Robinson now have bidon cages! So far, so good…


MKS Pedals

I’m a fan of clipless pedals but on my folding bikes I sometimes want flat pedals & for travel/transport I want the bike compact. To me, the MKS removable pedals have filled the bill. I have flat & clipless pedals that are the “pre-Superior” models (the Superior model uses an adapter that has an improved locking device but there isn’t a clipless model & the adapters aren’t compatible with the earlier adapters). For the clipless pedals, you need to use the MKS cleats for your shoes & these are compatible with both MKS & Shimano clipless pedals (ie the Shimano cleat is not compatible with the MKS clipless pedal).

MKS provide a yellow nylon circlip for the non-Superior removable pedals, as a safety locking device for ensuring the pedals don’t unexpectedly disconnect from the adapters. To me they are a nuisance & slow down the removal of the pedals when necessary. For the clipless pedals they hardly seem worthwhile because your shoe is locked to the pedal, but on the flat pedals a soft-soled trainer-type shoe is broader & may come in contact with the adapter (& possibly release the pedal). My solution was to fabricate an alloy plate to bolt to the adapter end of the flat pedal, ensuring that any shoe cannot come in contact with the adapter (see pic).


When Ralph came along, I noticed that the front tyre can release the right side clipless pedal when Ralph is folded (it seems to be a factor of the widened frame & the Kojak tyres (see pic). As I don’t often have to remove the right side pedal, I’ve fitted the MKS circlip on that side.


Cadence for Ralph

Ralph is using my Garmin Edge 705 bike computer & I decided to try fitting the cadence sensor. (Owing to the Brompton small wheels, it’s not possible to make use of the wheel speed component of the Garmin sensor but that was ok; the 705 gives me wheel speed via the GPS.)

The usual position for the sensor would be on top of the chain stay arm of the rear frame, with the crank arm magnet on the end of the crank. However, Ralph has a widened rear frame to fit the Alfine 11speed hub & there is no clearance for the crank arm magnet when Ralph is folded. I tried mounting the sensor on the vertical leg of the frame but discovered that the magnet then passes the sensor in the wrong plane (giving erratic/doubled cadence values). I nearly gave up but then tried cobbling up the sensor onto the frame joint (see pic) – & so far, it seems to be working!

Campervan passenger

Our campervan, a VW T5 Transporter, has a Brompton-sized space under the bed. Here’s Robinson, tagging along on a trip to watch the cycle racing at the Australian RoadNats & the TDU.