High Concept…

So in my ongoing efforts to rediscover a bit of pace in my RC racing, I’ve updated my Mini…


Behold the Tamiya M-07 Concept!

The car has been available for over a year and lots and lots has been written about it already so I’ll keep it brief:

  • As soon as you start building it you can tell it’s a true race chassis – a massive step up from the M-05 in design and materials
  • It’s a lot easier to set up because of the flat chassis bottom
  • Only issue in the build was a bit of friction between the hubs and the wishbones
  • The only hop ups I’ve added are 5mm alloy wheel hexes and some standard length TRF dampers
  • On track, the standard driveshafts bind up at full lock so I will try the DCJs
  • I’ve seen comments about the body posts being in a different position but it’s not the case with this shell which came straight from my M-05

Pit pic taken at Forest Raceway – a permanent carpet track west of Gloucester. It’s a fairly small track, but has a very smooth surface, plenty of indoor pitting and a friendly atmosphere. Had a really productive shakedown session, and despite hitting the boards far too often, nothing broke!


Quick tip for TT-01 owners…

Drivetrain feeling rough on your TT-01/TT-01E?

Try loosening the upper screws on the gearbox covers. A quarter-turn at a time.

It’s a bit of a hack to loosen the bevel gear mesh, but it seems to work!

Got a hunch it may be related to the black gears that come up a bit larger than the old white gears.


The Hyundai i20 smartphone dock… so close yet so far…

After dabbling with a “future classic” (the Audi A2) for 8 months, I have moved on to a much more conventional car – the Hyundai i20.

My reasons for buying it were almost exclusively logical. It fulfils more of my needs than anything else I could afford. My passion for the Audi didn’t really work out…

One feature of the i20 is an integrated smartphone dock. This seems to be a great idea – tap into your phone’s abilities as a sat-nav and music player, without having cables dangling all over the place and not-so-sticky mounts falling off the windscreen whenever you go around a corner.

But it has more than its fair share of problems…


The dock itself is sturdily built and clips into a special socket on the top of the dash (which you can cover with a blanking plate when not in use). Even though it sits on top of the dash, it doesn’t obstruct my view forward (although if you are shorter or have your seat low it might).

There are a couple of buttons to adjust the fit around the phone. The button on the bottom allows you to adjust the support for width, while the button on the top releases a ratchet to open the whole mount to install/remove the phone.

Two battery connectors are supported – Micro USB and Apple Lightning (I believe USB is “standard” with Apple as an option).

And this is the first problem:

  • There is no support for USB-C

The holder will accept a phone up to 145mm in height. And this is the second problem:

  • Most modern phones are too big to fit

The i20 came out in late 2014, and the holder was obviously built for the flagship phones of that era – the only ones explicitly supported are the Samsung Galaxy S2/S3/S4/S5 and the Apple iPhone 5 & 6 (but not the 6 Plus).

My Moto G4 does not fit (far too big). Nor does my daughter’s Moto C (USB socket in wrong place).

Nevertheless I was keen to see if I could find a “cheap” way to use the integrated smartphone holder. I don’t like the Samsung phones in general, and even the old Galaxys are far from cheap, so I looked elsewhere, and bought the Google/LG Nexus 5 – a 2013 flagship.

It doesn’t fit either! (The USB socket is upside down).

I was going to leave my experiment at that, but then I got an eBay reminder for a Moto X (2014) that was going VERY cheap – so I put a silly low bid on it that had no chance of winning.

A few days later I received the Moto X in the post.


The Moto X fits! (kind of). The USB socket won’t connect if the plug on the holder is inserted fully, however if you only push the USB in half-way, it will. Once you have got it in the right place, it does seem to stay connected when you drive around.

But… this is where the third (and perhaps most critical) problem appears:

  • The charge rate is really low

I’d say it is 0.5A at most. Which is understandable, as that is the original standard for a USB cable, and would be safe for anything.

The problem is, standards have moved on, and charging the Moto X at 0.5A isn’t enough to stop the battery from running out…


Here is a shot of the Moto X “just running” with the screen on. It is using 848mA of current in this state.


And here is a shot the the Moto X plugged in. See how the battery is coloured green but still has a status of discharging? The net mA flow is -365mA – basically, the extra 500mA coming from the USB port isn’t enough to offset what the phone needs to “just run”.

Even if you have a phone that fits the dock, the chances are that the battery will be flat before the end of a long journey anyway.

This makes it impossible to recommend – which is a real shame.

If Hyundai are reading this – I would normally make an appeal to you to support USB-C, and revise the mount to accept larger phones. But since the limited charge rate is almost certainly hard-coded into the car itself, there wouldn’t be any point…

(I’ll probably keep hold of the Moto X though… it’s a nice phone!)

Sit up and beg… the Humpert Ergotec High Charisma stem

Apologies if I have mentioned this before, but I suffer from a bit of a bad back.

Fortunately it is not very serious, but sometimes it seems like half of my waking hours are spent trying to get comfortable.

On my bike, I favour a more upright riding position. The standard geometry on my Giant Roam is OK – because I am tall-ish for the frame, the bars end up about level with the saddle, and have a bit of reach to them. Good for enthusiastic riding; not too uncomfortable around town; but not quite perfect…

My first change was to try swept-back handlebars instead of the fairly straight risers that came with the bike. I picked up some cheap Chinese bars from eBay, which were delivered very quickly and turned out to be pretty substantial. What I gained with the backward sweep was partially lost by the decreased height (because the bars need to be angled down). Definitely more comfortable – but I needed to get them higher.

There are a lot of “high rise” stems available but the one that really caught my eye was the Humpert Ergotec High Charisma – because it is the only one that I have seen that is actually shaped to flow smoothly into the top of the stem itself. I was baulking at the price until I noticed that Amazon were doing them at a serious discount – I paid just over ¬£16!

The shots above should give an idea of how it compares to the standard Giant stem. The Giant stem is marked as 100mm and 15 degrees; the Ergotec is 90mm and an unknown angle (but no less than 45 degrees in my opinion). They also offer a 110mm version.

I wasn’t sure how the 90mm would be measured, but it is the distance of the centre of the handlebar from the centre of the steerer, measured along the centreline of the stem tube (rather than being the horizontal offset).

Although the relatively shallow angle of the Giant stem means the horizontal offset is still close to 100mm, the Ergotec stem’s horizontal offset is much, much less.

Because of the extreme angle, the Ergotec stem has a horizontal offset of only 70mm or so, and a rise from the base of the stem of about 95mm. Compare this with the Giant’s rise of 40mm. In old money, the Ergotec stem brings the bars an inch closer and lifts them two inches higher!

Giant Roam – slow commute edition!

Fitting was straightforward – the closed top of the stem means you can’t adjust the height using spacers (I had to use the same spacing as the standard stem in its highest setting). No concerns with the quality either – there is a neat rubber seal to protect the top bolt.

Looking at the bike, I was a bit worried that this extra rise might be a bit too much… thankfully, it isn’t. A quick ride around the park has confirmed that I now have the “dutch bike” seating position I was searching for. Should make the commute a lot more comfortable!

All I need now is for it to stop being so cold and wet…

Tamiya #42313 Large Shim Set for Gear Differentials

But first, a little background…

Effectively, I haven’t been racing for the past 3 years. Personal circumstances and choices meant I could’t attend club races regularly, and because I wasn’t racing regularly, I felt less inclined to attend the bigger events.

Last year, I tried to race in the Iconic Cup, and for whatever reason I had lots of problems, and didn’t achieve what I felt I should have done.

This winter, I tried again with the CWIC XRS (run by the Chippenham club). Again, lots of problems with the car, combined with being well off the pace.

I would be intrigued to know what is the root cause of the problems – lack of practice, my increasing age, outdated equipment, or simply a lack of motivation. Sadly, I don’t know the answer.

What I do know (and this is what leads me on the the real topic of this post), is that if you under-perform, you end up in races that you shouldn’t be in, where driving etiquette appears optional. And you get battered.


I am still running my Tamiya/Samix TRF418 with the 419 rear diff. It is a car I have struggled with on many occasions. As the winter progressed, I managed to get a degree of consistency out of it on the new-to-me Hudy tyres and ETS carpet. Unfortunately, consistency doesn’t count for much when you get punted repeatedly by lapped traffic.

The rear diff broke – breaking an input gear and coning the shims.

While searching for some replacement parts, I spotted these:


The set includes 2x 0.3mm shims to go behind the input gears, 2x finer 0.1mm shims for the same location, and 4x 0.1mm shims to go behind the spider gears. As these shims are the same size as the gears themselves, loading should be much more even, reducing the tendency for the shims to cone. Also, the large size should make it harder for oil to find it’s way through the seals, reducing leaks. We’ll see if this works out in practice.

In terms of re-assembling the diff, I always shim the input gear so that it rotates smoothly with minimal backlash. Just one 0.3mm shim was enough for this on both sides. I will reappraise the shimming next time I have the diff apart.

I also put a 0.1mm shim behind each of the spider gears, and assembled the diff dry to make sure everything worked smoothly, again with minimal backlash. It did, so I filled the diff with oil (#2000 for now) and put it back in the car.

I have to say that I don’t buy in to any of the diff-building “voodoo” that you may read about elsewhere. Tamiya’s parts are fundamentally good quality. I don’t sand down the gears, I don’t weigh the oil, I don’t use special slime on the seals. I just lube the seals with the normal silicone oil, make sure there is no flash on the gears, and fill the diff until the fluid sits just above the cross shafts.

Plan is to get this on the track again this week and see if it runs properly again. Will be glad to put this winter’s racing behind me!


Diagnosis: Puncture

(with apologies to Dick Van Dyke)

Punctures are frustrating.

But what can be even more frustrating is working out why they happen. And why they didn’t used to happen. And why they seem to be affecting perfectly good tyres and inner tubes…

Giant S-RX4 tyres

My bike left the factory with these Giant S-RX4 tyres. They are a pretty high-volume hybrid tyre at 700x40c, and for well over 6 months and 1,000+ miles of city riding they did not cause me a single problem.

Then one day, I got a puncture. OK, these things happen, and it is pretty easy to repair.

Two weeks later, I got another puncture. I guess there must be a lot of debris on the streets at the moment.

The following week, another puncture. Starting to get a bit frustrating.

The next week  Рtwo punctures Рone of them on a family trail which could have easily spoiled the whole day (fortunately I had a spare inner tube after the previous repairs).

I really needed to work out what the problem was.

What I found strange was that the tyres did not have a huge mileage on them, and there was still plenty of visible tread. But then I noticed that small chunks of glass were getting embedded in the tread (and I mean really small – only a few millimetres across).

You can just about see the tiny chunk of glass in the centre of the tread

It wasn’t taking much for these small chunks of glass to work their way through to the inside of the carcass, puncturing the inner tube.

But why was this happening now and not in the previous 1,000 miles?

Well, pliers and scissors helped to explain why…

Cross section of the tyre

Put simply – the tyre is pretty thin and there doesn’t appear to be any form of puncture protection.

The rubber has worn down and is less than 3mm thick along the centre of the tread ( decreasing to 2mm at the edges). No wonder a 3mm chunk of glass can penetrate the carcass!

Goes to show that even a tyre with a visible tread pattern could be worn beyond its useful life.

Naturally, I decided that I had to buy some new tyres.

The two most popular puncture-protected brands seemed to be Continental and Schwalbe. You can normally count on German engineering. I chose the cheapest ones I could find and settled on the Continental Contact II.

While I was waiting for them to arrive, I got another FOUR punctures in just one week!

Fortunately, the Continental’s have yet to cause me a single problem. And I daresay that they feel a little faster!