Category Listing: Bikes and accessories

Stuff about bikes and accessories. For example, good and bad purchases. Bike reviews.

Bonking and cycling don't mix

Andy Henderson describes a potentially dangerous condition you might encounter, what to do about it and ways to prevent it.

In cycling we talk about 'bonking', in running they talk about 'hitting the wall', the medical term is Hypoglycaemia. Your body runs out of readily usable fuel. You are close to fainting on the bike, with all the dangers that could result. It's a condition that usually happens on rides that are demanding because of length, hilliness, weather, or maybe all three. Or, maybe, you just ride too long without stopping.

When you get close to bonking there are a number of symptoms. The main one is extreme weariness. You might be pedalling on the flat but you feel like you're going up a steep hill. Any effort is difficult - even just turning the pedals. I get a nasty feeling in my stomach - a lot like nausea. You feel like you can't carry on. The feeling is hard to explain but, once encountered, it is unmistakeable. It can come on suddenly without warning. Although I've not encountered them, sites also list symptoms including:

  • Loss of focus
  • Loss of vision or impairment
  • Cold flashes throughout the body
  • Shaking
  • Sweating
  • Heart palpitations

Please take action...

... if you see someone weaving for no reason and they're complaining of extreme tiredness, maybe they're even incoherent. They might be about to faint.

The problem needs to be tackled, and the rider might not be in a good state to recognise what is happening.

You need to stop and get off the road as soon as it is safe to do so. Ideally, someone should stay with you. This is not a good time to be on your own.

When you bonk, your body has got very low on glycogen. It has little left to run on - and wants to shut down. You need some quickly-absorbed carbohydrate. I carry fruit pastilles (not the sugar-free kind). Energy gels will also help (but I can't stand them). A can of coke will also work. Basically anything with easily-absorbed sugar. If you’re lucky enough to bonk within a stone's throw of a café then that’s another option.

Obviously you shouldn't try to get going again until you've given your body time to get some glucose into your bloodstream. When you do get going, keep another rider behind you (if possible) looking out for a recurrence. Take it very easy. If you are a long way out, consider finding a railway station or calling for a pick-up. Otherwise, go straight home.

Avoiding the condition

If you Google "cycling bonking" you'll find plenty of good advice some of which does not apply to the type of cycling we do. The basics are simple:

  • Fuel up before you start the ride
  • Top up your energy as you go
  • Drink plenty

Giving blood...

... can result in similar symptoms to bonking. Although blood plasma is quickly regenerated, your red blood cells (which carry oxygen around the body) take longer. And that time increases with age. In effect it is reverse EPO. It's not the same condition as Hypoglycaemia, but it has similar effects.

Have a decent breakfast that includes slow and fast release carbohydrates. Starting a demanding ride on an empty stomach is asking for trouble. Many use porridge with sugar or syrup. If it's a long ride you'll need to have a decent lunch (not a lot of fatty food, however, that can slow glucose absorption). I know some riders have a pint of coke (virtually liquid sugar).

Take something with you to top up your energy as you go. And take every opportunity to drink - small, frequent sips are best - gulps of water tend to trigger the 'pee response'.

Some use energy gels. I use this stuff added to my water bottles. That's a triple whammy:

  • Hydration
  • Energy supplement
  • Replacement of electrolytes (lost through sweat)

In summary

Please don't let any of the above put you off distance riding. As long as you are comfortable on your bike and you are aware of your body's needs, bonking won't be an issue for you.

Take care of your fellow riders and be on the look-out for problems they might be having.

And enjoy the ride.

Looking after jockey wheels

Jockey wheels feed your chain around your rear sprockets and force the chain to move between gears.

The wheels run on bearings which wear over time as can the teeth.

Excessive movement in the upper wheel means the gears won't change when you shift (forcing you to shift twice and back again to change a single gear) no matter how much adjustment you make. Worse, jockey wheels can seize.

To check your jockey wheels, either:

  • Remove your chain; or
  • Take it off your front gear so the chain is loose and you can pull it away from the jockey wheels.

Look for:

  • Lateral movement of the upper wheel (some lateral movement of the lower wheel might be by design)
  • Worn teeth
  • After cleaning, the wheels don't spin smoothly

Replacement jockey wheels come in pairs. Normally there is a difference between the upper and lower wheels and they have to be fitted right way round. Replacing them is easy - once you've figured out which wheel is which and which way round to fit them.

On my bike (SRAM Force 1) the inside hole of the upper wheel is slightly larger so it cannot be fitted in the lower position or the wrong way round. It doesn't matter which way round the lower wheel is fitted.

Other wheels will be marked with an embossed "U" (upper) or "G" (guide), and "L" (lower) or "T" (tension). Normally, the wheel indication faces out away from the bike. Some show an arrow showing rotation direction (it can be a bit mind-bending to work out which way they rotate when fitted).

This video shows how easy it is to replace your jockey wheels...

For common Shimano jockey wheels I've used Tacx - as recommended by Alan Morgan. These come with a set of plastic inserts so, provided you match the speed (number of gears at the back), there's a good chance they'll be compatible with your bike.

I bought these ones recently as they have the narrow-wide teeth used by my bike.

Decathlon Northarbour opens Thurs 25-April

Decathlon is opening its store in Northarbour tomorrow (Thursday 25-April-2018), near the Tesco Extra, and they're offering free backpacks for the first day if you have a Decathlon account and card.

They do a fantastic range across all sports at great value, but especially cycling, and their bikes get great reviews. Disclaimer: I bought one of their fantastic folding bikes, and it's the most fun bike I've got - I'm certainly recommending it.

Previously, the nearest store was West Quay Southampton, which is a bit of a trek for us here.

More details at

Replacing a hood

Following an unplanned meeting with a gravel path, one of the hoods on my bike got ripped, so I looked for a replacement. It was more difficult than I expected, but I finally succeeded.

HoodsI first thought I'd found just the thing on Amazon for a reasonable price (but, all the options I found were for a left and right hood, so I had to buy two when I wanted only one). When it arrived, however, it was obviously too small to be the right part. I'd ordered a SRAM Force 1 hood not realising there were two versions: one for hydraulic disk brakes and one for cable pull brakes (the hydraulic fluid reservoir sits above the levers making the unit taller). Oh well, it was easy to return. I downloaded a parts list from SRAM and found the exact part number I needed and Googled that. I found a matching hood on eBay, sourced from China. It said it was a genuine part and I was encouraged by the correct part number, so I ordered it. A few days later I got an email to say that there had been a manufacturing problem and did I want to wait a few weeks. I couldn't see how that could have happened for a genuine part, so I assumed it was a fake copy and immediately cancelled. I finally managed to order the correct part on eBay but it took a bit of detective work. The advert didn't include the part number, but:

  • The item said the hoods were for a SRAM Force 1 hydraulic shifter
  • The picture looked right
  • The enlarged picture had a faint 'Hydra' logo which matched the ripped one
  • The source was in the UK

The hoods I received matched exactly and came in a SRAM box - but I've no idea whether they are genuine or not.

Then came the difficult bit.

The hood fits over the shifter through the base and there's a cut out for the brake lever. So all you have to do is pull the old hood off and pull the new one on. In my research I'd seen several reports of people being able to do that without disassembling the shifter. The trouble was that the openings looked far too small to fit over the shifter. No way could I pull them on and off! Then I found this video:

They do pull on and off but you have to really stretch them. Mine were more difficult than the ones shown in the video because I had to pull them over the oil reservoir. Thankfully, I could practice using the old hood. It still took a bit of courage to pull the new one on, but after a few minutes struggling it went on!

Anyone want a right hand SRAM hydraulic hood?

Set up OsmAnd & online tracking on Android

OsmAnd is a mapping, planning and tracking app for smart phones. It has a number of benefits:

  • The app is free
  • You can download up to 7 maps for free (England is one map) and costs for additional maps are low
  • Maps are downloaded to your phone so you don't need internet access to use them
  • Maps can be downloaded to an SD card (useful if your device has an SD slot and limited main memory)
  • You can track your route, and/or follow a pre-planned route
  • Includes route planning
  • Includes a feature to interface with our online tracking service
  • Lots of features and options

Several Portsmouth CTC riders use it already including Me and John Rosbottom - could you get a higher recommendation?

Note that you do not need the app to monitor where people are on a ride. For that you just need an internet-connected browser.

This article explains how to get OsmAnd onto your phone and - if you want - how to link it to our online tracking service. The notes and screen shots are from the latest version of Android at the time of writing, Marshmallow. They should also apply broadly to previous versions although there will be some differences.

The following sections include some Android screenshots. Click any one for a larger version.

To install OsmAnd, click any of the following for more detail:

Connect your phone to the internet

If at all possible, connect to wifi (rather than mobile data) before you start. Installing OsmAnd and maps involves a lot of data, using wifi could save a lot of money and/or a big hit on your monthly broadband allowance. If you use wifi, try to get as close as you can to the router box - it could significantly improve download speeds.

Use Google Play to install OsmAnd

Look for the Play Store icon on your home screens:


Tap the icon. If you can't find it, click the apps icon at the bottom of any of your home screens:


You should see the Play Store; in the alphabetic list of apps, tap it to go to the Play Store.

In the Play Store, enter "osmand" in the search box at the top:


Tap the entry for OsmAnd (the first entry in the screen shot above - note the icon should be the same (unless OsmAnd has changed it since).

Now tap 'Install' at the OsmAnd screen and follow the prompts to install it on your phone.

To put an OsmAnd icon on one of your home screens, go to the home screen where you'd like it. Tap the apps icon:


Find OsmAnd in the list. Press the icon until you see the home screen and drag the icon to the position you want.

Download the maps you need

Tap the OsmAnd icon to run it. You'll see a display like this (although you won't yet be able to see a map):


Tap the 'three lines' menu icon at the bottom left to see this menu:


Now tap 'Manage map files' to see a screen like this:

Tap 'Europe', 'United Kingdom', 'England' to see something like this:


Tap the download icon to the right of 'Standard map' to start downloading your map of England.

You can use the above mechanism to download detailed maps from around the world.

Install the 'Trip recording' plugin

Start OsmAnd to see something like this:


Tap the 'three lines' menu icon at the bottom left to see this menu:


Tap 'Plugins' to see a list of plugins. Tap 'Trip recording', then 'Get' to download the plugin.

To connect to our online tracking service, click any of the following for more detail:

Connect your phone to the internet via mobile data

To connect to our online tracking service, you need to be able to connect to the internet via mobile data. There's no issue using wifi where it is available, but while out on the road, mobile data will be your main means to connect.

If you already use mobile data while you are out and about, you won't notice the extra data used by the tracking service - it is very frugal.

If you have mobile data switched off so that you connect to the internet only via wifi, switching mobile data on can lead to nasty surprises as other apps pile in to use mobile data while you are not using wifi. If you are a pay-as-you-go customer, you might see your balance quickly drop to zero. If you pay a monthly connection fee, you might see your data allowance disappear.

Before you switch mobile data on, you should therefore consider installing a firewall app like NoRoot Firewall (my preference) which allows you to control which apps can use mobile data. I've found, though, that even this doesn't fully control use of mobile data since Google code is allowed to by-pass the firewall. I plan to produce a tutorial (or find one on the web) to cover this when I have time.

Configure the 'Trip recording' plugin

Start OsmAnd to see something like this:


Tap the 'three lines' menu icon at the bottom left to see this menu:


 Tap 'Plugins' to see a list of plugins. Tap 'Trip recording' to see a screen like this:


Tap 'SETTINGS' to see...


I'll be honest, I don't know what effect your selection has here. Having experimented a bit, the settings seem to apply regardless of which option you choose. I always choose the cycling icon, and have the same icon selected on the main OsmAnd screen.

You will then see the trip recording settings...


It's worth going through them all. For the time being, though, swipe down to the bottom of the list to see the online tracking settings...


Tap 'Online tracking' to tick the checkbox (as shown above). You will automatically start logging your position to the web site any time you are tracking your route and you have mobile data switched on.

Tap online tracking web address to see a screen that allows you to specify how OsmAnd should talk to our web site. Enter the address exactly as you see it here...


... except that you should put your web site user name (the id you log in with) instead of xxx and the tracking password you set in your profile (more about that here) instead of yyy. The password is case sensitive so make sure you enter upper and lower case characters exactly as you entered them in your profile. Note that the address does not contain any spaces or newlines.

Finally, tap online tracking interval to see:


We suggest you select a 5 minute tracking interval, as shown.

Test online tracking

It's worth checking that online tracking is working before you use it for real. To do that, go outside to make sure you have a decent GPS signal. Make sure mobile data is on (via Android settings: Data usage). Start OsmAnd and, on the main screen...


Tap the 'GPX' icon at the top right so it turns red. After 5 minutes, check the online tracking page to see if your position appears. If it does, you're ready to go. If not, check the following:

  • Online tracking web address - it must be exactly as specified above
  • The online tracking check box in the trip recording plugin is ticked
  • Mobile data is switched on
  • You have a mobile phone connection
  • You have a GPS fix (I find an app called 'GPS Test' useful for that)

Stuck Seatpost

The seatpost on my Dawes Galaxy had been stuck for over 2 years. I couldn't move it and neither could the bike shop. At first I wasn't too bothered but when I was fitted for my new bike I realised that the saddle on the Galaxy was too low making it less comfortable and inefficient. I searched the web and methods of sorting it looked rather extreme and risked damaging the frame. Then a club-member suggested the Seatpost Man. He (John Lee) is based in Chorley, Lancs so not local but on the way to the North. He was very good at agreeing a time to suit me. I left the bike with him and in 2 hours it was done. Cost £60 but cheaper than a new frame and the bike is now a pleasure to ride (as well as being easier to pack up for touring!).

I'd definitely recommend him to anyone who has a similar problem. And what an excuse for a trip up North - cycling or otherwise!

Using a tyre boot

Figure 1A tyre boot is a piece of material used in the temporary repair of damage to a bicycle tyre such as a cut to the tyre sidewall. Figure 1 shows a typical sidewall cut. You can see there is a danger that the inner tube will pop through the cut and burst. A tyre boot temporarily covers the cut to prevent the (repaired) inner tube from further damage. The method described here is not suitable for tubeless tyres.

There are a variety of methods and materials that can be used and the following description is but one of them and successfully used by the author.


The material needs to be strong and thin without any sharp edges – strong enough to prevent the inner tube from poking through the cut whilst thin enough to 'wedge' unobtrusively in place, and of course have no sharp or irregular edges to damage the inner tube. Candidates for this include a piece of inner tube cut from a spare, a piece of leather, a £5 note/$1 bill or similar, and so on. In this article I use a piece cut from a toothpaste tube. The tube is plastic on the outer with a thin metallised covering on the inside. Figure 2 shows three pieces cut from one toothpaste tube.

Figure 2

Applying the Tyre Boot

Figure 3First, replace or repair the punctured inner tube, put a small amount of air in the inner tube and fit back under the tyre leaving one side of the tyre 'unhooked' from the wheel. Take one of the tyre boot strips and place it between the inner tube and the damaged part of the tyre wall, leaving the excess material protruding for the moment. Figure 3 shows this: note the yellow marks on the tyre which are used simply to show the location of the cut.

Fully fit the tyre back into place by easing the tyre bead over the wheel rim, trapping the tyre boot under the wheel rim bead hook and preventing the tyre boot from moving out of place during and after inflation. Figure 4a shows the tyre fully inflated with the metallised side of the tyre boot showing through the tyre wall cut. Using a sharp blade, cut the excess tyre boot away (cut down onto the wheel rim, NOT toward the tyre wall!). The trimmed result (Figure 4b) is a neat finish which at the time of writing has done 60 miles plus with no sign of weakening with the 700c x 25c tyre inflated to 7 Bar / 100 PSI.

Figure 4aFigure 4b

Finally, the tyre boot, wrapped around a hobby knife blade weighs about 2gms, costs pennies and fits neatly into the average puncture repair box. To include a tyre boot 'kit' into your repair outfit may well save you or a cycling buddy a long walk home!

Alan Morgan

Checking/replacing a derailleur hanger

Until I saw this video, I had no idea what a derailleur hanger was, or what it did. It turns out to be a useful part to know about and is easily replaced if necessary...

Checking/replacing a drailleur hanger

Making gear adjustments

These two videos describe how to make adjustments to your gears:

Set your derailleur limits . Note this video makes no mention of the 'half cock' position that some bikes use to allow the full range of rear gears without the chain rubbing against the front derailleur. If your bike has that feature, you'll need to use it to check all combinations of gear positions work OK.

Adjust your indexing .