Little boys that is. And it is an area fraught with difficulty if you do not want to be a Disappointing Dad. The test for this is a small boy’s silence or even worse a half smile.You could walk into a supermarket, a discount chain or even order from a newspaper advert and buy an astonishingly cheap bike and although it may cope with the occasional bridleway, it may struggle with regular trail duties. Your local bike shop may carry one of the major players who make a kid’s version of your own steed.That may be an easy solution but only if it is going to be used and not end up joining other investment items which you store unused in your garage.

Some web sites offer frames or bikes with useful information on sizing and weight. These can be a good point of comparison.

However we all have a shed or garage with lots of unused kit which would be ideal for someone else because you really needed Steve Peat’s grips and Cedric Garcia’s bars and your old ones are on the shelf and if not you really need some new wheels anyway so that would not count on the costs of course.

After a little research, I settled on a hardtail with a maximum target weight of 25 lbs. The frame was a real problem as advertised sale items were plentiful but finding actual stock proved difficult.

Merlin had an older model which seemed ideal but the cost was a large chunk of a whole bike from a chainstore but I felt that the quality would be better and the weight a little less so that help justify it.

I was so pleased at the silver frame when it arrived I choose forks specifically to match and although I had intended to use as much of my shed stock as possible that changed to only shiny silver bits. I did reuse some wheels and some v-brakes but bought new handlebars, stem, seat post, clamp and saddle to match the frame.

I had expected to buy much of this from whatever internet retailer was offering a discount but Halfords provided some bits cheaper and most importantly in silver.

All the bits laid out brought a smile to the face of an eager boy that only fell slightly when I explained that assembling it himself would be good for him.

I felt sorry for his teacher when trying to explain the method of installing the crown race to the fork as he fiddled with just about everything else.

After much ado, and over a couple of days, the build slowly accumulated. The bottom bracket was fitted, the fork, stem, bars, seat post and saddle but it did not look like progress. Tubes and tyres, a cassette and quick releases and the wheels fitted. Now it looked like a bike and if you are twelve then surely it is almost finished now.

Shifters and brake levers, fit the v-brakes, now the brake cables, this is how you adjust them. How much longer Dad!

By the time we had measured cut and fitted the cables the set up of the transmission seemed to be an unnecessary punishment so I crumpled under the pressure and finished all the little bits myself somewhat later.

The finished bike looked great and a satisfied smile and a brief, “thanks Dad”, means that I have passed the test.

For a couple of hundred pounds we have enjoyed a joint task and he has learnt a few new skills. He can join me around the trails of Sussex and I can impress him with my hard won skills built up over years in the mud.

Unfortunately, there is a downside to this.

Like many of you out there, I tackle the steepest climbs with determination, the knurliest roots with courage and even the occasional shallow river crossing with gusto but I cannot jump.

Well I can jump a bit, the odd lip here, a small drop off there but nothing big. Not anything, you find in a BMX park, not even if it is a tabletop.

And there is the rub.

First time out at Whiteways, slippy, treacherous, rooty single track, straight over the top. A drop off with a steep edge, straight down, and even the large bomb hole drop, straight down. Now I have led a few rides round here and usually a few people shy away from this drop or at least need some reassurance to roll over the edge. So all my advantage gained from years of experience evaporated in just one ride.

But this pales into insignificance with jumping. Tricky log – jump that. Tight awkward corner – jump that. Ditch – jump that. Big rock – jump up, jump off. Great big hole that you must avoid – jump that.

It gets worse. Standing at the side of the track watching your little baby boy hurtling towards the jump ramp that you have ridden around for years looking at sideways thinking one day, one day. He launches himself a metre into the air, hangs suspended, lands three metres after the spot you were assuming to be the landing area and all as gently and as lightly as a little deer.

I will never be able to do that even if I threw caution to the wind and hurled myself towards potential oblivion with careless abandon risking life, limb and mortgage payments.

And if I did, I would land more hippopotamus.

So if you have to face the choice then do not be the Disappointing Dad who picks the wrong bike instead choose to be the Disappointed Dad that Father Time has cruelly exposed.

After all, we can all live vicariously.