I have one of those kids seats which is supported from two bent steel(?) bars that fit into a clip that clamps onto the seat tube. With first child it lived on my bike until he graduated to a tag along. Now with second child Mrs Poly wants the kids seat on her bike.

But – she’s a short-arse and has a women specific small frame (specialised hardrock) and even mounted at the very top of the seat tube the seat fouls the rear wheel. However I think there would be enough space to put it on the seat post. Never seen one like this – but tagalongs are often mounted like this with no apparent problems. The seatpost is the standard one that comes with the Spec 2007 Hardrock – so is not some super-light, ultra-expensive, NASA-material thing.

So thoughts on whether this is likely to damage the seat post, or the frame (through the increased leverage) ? Or better still has anyone else done this – or found a simple solution other that buying a different design of seat?

the ‘bent steel bar bits’ (there should be a name for them) are available in several different shapes for some brands of seat, you may be able to get just that bit.

Had a Hamax seat for my kids and, whilst it seems a solution to the problem (distance between the seat and rear tyre was less than 10cm iirc when I ran the seat on my small Klein frame which lead to a bit of noise over harsher bumps), I’d never have risked attaching to the seatpost just from the horrific thought of what could happen to my kids if the seatpost did fail.

I have a Orange Patroit 66 EXCL. There ia no space on the frame to attach the kids seat of this type. So had to attach it to the Thompson seat post just above the seat clamp. Never had any problems with this, even when taking small jumps. I had to protect the seat post with an old inner tube and make sure it was bolted on very tight. As long as you bolt it close to the seat clamp there will be less stress and leverage on the seat post, and a hardtail bike will produce less bounce and flex in the steel bars.

the tag along is not comparible because it is not bearing any weight rotationally – it is just pulling the weight along the ground. I’d say you’d probably be ok, but i’d recommend –

– clamp it as close to the frame as you can
– run as much seatpost inside the frame as you can
– buy a steel seatpost, bmx style (think atomlab GI) very thick metal, very heavy, very strong – you can get them for under 20 quid
– if you can, get a taller double-bolt seat clamp, which you can pick up for a fiver.

just little things like that that spring to mind to make it safer – I dunno about using thompson seatposts – sounds scary to me!

think about it ……

just buy a cheap second bike (second hand) and put your seat on that ….

ive seen some horrific failures and really badly fitted child seats. Parents are absolutely mortified for the most part when you point out how badly fitted some of them are !

thanks for the feedback guys. I’ll take a trip to the LBS this weekend and work out the options in terms of alternative brackets or a new seatpost etc.

id be worried if the bikeshop lets you mount it on the post

have you bought the child seat yet ? if not id recomend going for a buddy explorer trailer at 119.99 RRP from any moorelarge dealer (most lbs) and it mounts to the rear axel and chainstay !

Certainly wouldnt have my(hypothetical) kids in a rack mounted on the seat post !

Its an accident waiting to happen – best case scenario is a busted seat tube/top tube weld and worse case is kiddie bouncing down road.

If you go to your LBS, ask them to show you an OK Baby Ergon or 10+ kiddie seat. They can be supplied with a ‘small frame’ specific mounting bar which should sort it out. They are supplied by Moore Large and the product codes are OSCOO1 or OCS010 if the LBS can’t be bothered to look in the catalogue.

Sounds like a bonkers idea to me.

trailrat: we already own the seat. We also own a trailer which is a different brand but the same idea as the one you suggest. BUT whilst I am a big fan of the trailer there are some times when its a bit of a PITA, not least because it won’t fit through the “anticar” gates on the canal tow path. I think Mrs Poly is also put off because every time she took it out she got punctures in the trailer tyres (being wider than a bike they tend to end up off the main path a bit and so more likely to collect thorns and the low rolling resistance tyres aren’t great for puncture resistance- hopefully slime tubes are going to help though).

I’m not too worried about breaking the seatpost as it is the same as mine so can take loads almost double what my wife puts through it. But I am more worried that a sharpish corner or stop will result in the seat/baby putting a twisting motion on it which will not be good (seat tries to overtake rider / sudden change in balance etc). Even if it just twists the saddle 10 degrees – that will be difficult for Mrs P to realign with a kid on the back – and it will be MY fault.

I think it is fair to say I am fairly open minded about risk and children. I sat in a child seat with no straps, no helmet etc at about 4 yrs old when I was a lad… Its unlikely that the seat post would spontaneously fail catastrophically from this sort of abuse (more likely to bend/crack/split – which I would spot because I am conscious of the “misuse”) but actually even if it did the results would be no worse than a crash which we have to accept is a realistic possibility either through rider error or other road user incompetence etc.

If you go to your LBS, ask them to show you an OK Baby Ergon or 10+ kiddie seat. They can be supplied with a ‘small frame’ specific mounting bar which should sort it out. They are supplied by Moore Large and the product codes are OSCOO1 or OCS010 if the LBS can’t be bothered to look in the catalogue.

Thanks Mudpup thats exactly the sort of information I was looking for. My seat looks identical to that (need to check if it is the same make or not). Found the Ergon info on line and the different mounting brackets look like they should solve the problem.

and if that's not enough, try this http://www.singletrackworld.com/forum/topic/the-mother-of-all-child-seats (shameless promotion i know…;-)