John C. Kirk (johnckirk) wrote,
John C. Kirk

Yo, pump it up ... to the max!

As I mentioned last month, I had some trouble figuring it how the new-fangled pump worked on my Brompton, so I wound up with a bit of a squidgy back tyre. Since I save quite a bit of money by cycling (I now pay £39.20/month for a rail season ticket rather than £169 for a travelcard), I figured that I should invest some of that saved money back into the bike. So, I bought a Topeak Joe Blow Max II Track Pump: in brief, I'm very impressed with it, so I strongly recommend that all other cyclists get something similar.

There's a tube attached to the base of the pump, and that has a TwinHead (TM) at the other end which you plug into the tyre valve. The TwinHead means that it can fit into different types of valve: in my case, the black side fits into a Schrader valve, while the grey side fits into a Presta valve. The basic principle is similar to the new type of hand pump, i.e. you wedge the head onto the valve then pull out the lever to hold it in place. The box has some handy instructions, showing which way to attach it:
Pump box
(Ignore the white rectangle near the bottom left - that's just a hole in the box.)

Due to the TwinHead, the lever can move in two directions, so you move it in the appropriate direction depending on which side you plug in. Based on the instructions, I assumed that you were supposed to move the lever towards the valve. I then noticed that the diagram wasn't quite accurate. There's writing on each side of the head, saying what type of valve you plug it into, and if you're holding it with the yellow lever towards you, you actually need to use the left hand side for a Schrader valve. Ah well, no matter; I just took the mirror image of the instructions. So, I pushed it onto my front tyre, moved the lever that way, and two seconds later I had a completely flat tyre. This seemed suspiciously familiar from my exploits with the handpump. I spent a while looking at the diagram, in case I'd misread it; in the end I tried moving the lever in the opposite direction, mainly because it was the only thing I hadn't tried yet. That did the trick, and in fact I got a much better seal with this than I did with the hand-pump. I think it also helps that I'm not jiggling it around once it's in place, i.e. the bit of the pump that I'm moving is a safe distance away.

So, here's how it looks when the pump is connected to the bike:
Pump connected to bike
As you can see, the yellow lever is pointing away from the valve, not towards it! Learn from my mistakes...

For this photo, I unfolded the bike, but I've found that it's better to pump up the tyres while the bike is folded. That way, the tyres aren't touching the ground, so there's nothing pushing them in while I'm trying to push them outwards. With a "normal" bike, I'd turn it upside down (saddle and handlebars resting on the ground), but that doesn't work very well with the Brompton.

There's a pressure gauge mounted on the pump near the base:
Pressure gauge on pump
The idea is that you put your feet on each side (to hold the pump still), then push down on the handles as if you're blowing up a building. You watch the pressure gauge, and keep pushing/pulling until you get to the right level. When I did this the first time, the front tyre was starting from empty. The rear tyre started out at 20 psi (from the handpump) and I got it up to 70 psi, which is a definite improvement. Mind you, for both tyres I could only get to the bottom of the recommended range; after that, the extra air just didn't go in, maybe because I wasn't pumping hard enough.

So, I think there are two advantages of the track pump:
a) It actually enables me to get a lot more air in, so that I can get the tyres to a higher pressure.
b) I always lose a bit of air when I detach/attach the pump, so having the pressure gauge built in is better than swapping back and forth between a separate gauge and a pump.

Unfortunately, as Michael predicted, riding around with a squishy back tyre has damaged the sidewall:
Damaged sidewall on rear tyre
It's not very easy to see the damage in the photo, so I've put red circles around it. Basically, it's cracked, so I can see the inner tube inside. I'll need to replace that tyre sooner or later, but hopefully it will hold up for a little while longer.

According to the Brompton website:
We can not overemphasise the importance of keeping the tyres well pumped up: soft tyres lead to a lot more pedalling effort (which takes much of the fun out of riding), wear out quickly, and have an adverse effect on handling.

I can certainly feel the difference in the tyres if I squeeze them (they feel rock hard), but it's hard to say whether it's easier to pedal now, given that I'm expecting a result. The main difference I've noticed is that the bike seems to "rattle" a bit more, as if there's a problem with the suspension. I'm not actually sure whether the bike has a suspension or not, but that makes sense, if the tyres no longer have any scope to "give" and cushion the impact of an uneven road surface. More generally, I'm getting up hills more easily than before, and I'm spending more time in higher gears, so it takes less pedalling to go the same distance, and I reach my destination more quickly. I don't know how much of that is due to the tyres vs the engine (i.e. improved fitness), but either way I'm not complaining.

Although my season ticket is cheaper, I do have to spend a bit of extra money on bus fares (previously covered by travelcard), e.g. if I go to the supermarket. This is because I wouldn't want to carry the Brompton around with me inside the shop, but I wouldn't want to leave it outside without a lock. So, I also recently bought a Kryptonite Evolution series 4 D/U-lock. It's not the most secure lock that they sell, but it's the cheapest one that gets a "Sold Secure Gold" rating.

Looking at this picture from my previous post:
Folded Brompton
There's a triangle of blue metal just underneath the word "Brompton", and that's where I attach the lock. I didn't go for the LS version of the lock (6cm longer), because the shorter version is fine for my bike, and I think that a snug fit is more secure (less space for a thief to insert a crowbar, car-jack, or whatever). It's working ok so far, in that nobody has stolen the bike yet, although I've only used it for short periods of time rather than leaving the bike unattended for several hours. I don't carry it on all my journeys, since it's extra weight, and I can't easily attach it to the frame of my Brompton, but it's useful to have extra options available to me.

Kryptonite have a deal where they offer to refund the cost of your bike (up to £1000) if it's stolen while using their lock. That's a nice gesture, showing confidence in their product, although there are a few restrictions. Firstly, it only applies if their lock was actually broken; if someone saws through the bike stand (or the bike itself), you're not covered. Also, you have to register the lock within 15 days of purchase, including the receipt for your bike (or an appraisal of its worth), which I forgot to do, and the guarantee only applies for a year. Still, it's better than nothing.

As a related issue, some supermarkets have better cycle facilities than others; this probably varies from branch to branch as much as it does from chain to chain. My local Sainsbury's has Sheffield stands outside (the things that look like big croquet hoops), so I locked the bike up while it was fully unfolded. The local Tesco doesn't have any facilities at all, so I folded the bike up and locked it to the hoop on the wall that's intended for dog leads. The Asda near work has the V-shaped things (apparently designed to buckle front wheels), so again I folded the bike and put it beside the stand.

When I cycled to Sainsbury's recently, it was a bit of a struggle, since much of the journey is one long uphill stretch. Still, that will probably get easier with practice, and the return trip is a lot easier! A more serious problem is that I only have limited storage space in my cycle bag, and I wound up carrying one (light) carrier bag over my wrist. I have a similar problem if I cycle to SJA duties, since I don't have room to carry my big high-vis coat, and I don't want to wear it while cycling. That's not really an issue at the moment, since the weather's been quite warm, but it will be more of a concern in the winter. One approach would be to get a trailer, e.g. the Bike Hod; the main snag is that it's quite expensive (£285), so it would take a lot of journeys to recoup the cost, assuming that my alternative is to pay £2 for the bus. Other options include the Carry Freedom Y-Frame, the BOB Yak (recommended by Breton Bikes), or the Weber Monoporter. Anyway, that's not an imminent purchase, just a vague long-term plan.

Finally, I've replaced the handlebar catch on my bike (part of the folding mechanism). When the bike is folded, the handlebar swings down, and a "nipple" on the handlebar stem clips into the catch on the side of the front wheel fork. This catch is a plastic V-shape, and when I first got the bike I was very impressed at the engineering involved: when I unscrewed the hinge for the handlebars, they swung down with exactly the right amount of force to click into place in the catch. Unfortunately, my catch broke a few months ago, when half of the plastic snapped off.

Here's a close-up of a side view, when the bike is folded (with the old catch):
Side view of broken catch
That's the catch on the left, and it could just about hold the handlebars in place while the bike was folded up and stationary, but the handlebars would swing out whenever I picked the bike up, e.g. when taking it off the train and carrying it between platforms.

I bought a replacement catch a while back, which only cost £3.50. However, none of my hex keys (aka Allen keys) were big enough to remove the old screw. In fairness, I've just hoarded them from old flatpacked furniture, and I only got round to buying a proper set today (£2.99 from the DIY shop downstairs). According to the instructions, I should use 9NM of torque, but that would involve buying a torque wrench. For now, I've just done it by hand, and I'll check it later.

Comparing the old and new catches, it's clear what went wrong:
Old and new catches

Similarly, here's how they look in situ (aerial view):
Aerial view of broken catchAerial view of new catch

It was actually pretty easy to do the replacement; the main problem was lining the new catch up properly, so that the nipple goes into the centre. The handlebars certainly feel solidly wedged into place, even more so than when I first bought the bike, although I may have blurred memories because I've got so used to the weak catch. Anyway, I'll see how it handles when I carry it around tomorrow, but I'm satisfied for now, and that's a small chore that I can tick off my "to do" list.
Tags: cycling

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