Knees brushing crossbar - Flat Feet ?

[Dzzi]

Hi All,

My 14 year old son who is around 5ft 7 has started to do a few rides with me firstly on my crappy old hybrid and last week on a lovely cube road bike in mallorca

He enjoyed the day in mallorca and there was some talk of getting a bike for Xmas (i've explained the n+1 rule to him so he knows what he's starting !)

He has a problem with the inner part of his knee(s) brushing the cross bar on both these bikes. He is VERY flat footed and at the moment is not clipped in just riding in trainers on flat pedals.

Has anyone got experience of this kind of issue ?
He does cycle very heels out but i think this is as a result of the flat feet?
Would proper custome made insoles ( he has these for his normal shoes) make things better ?

Any advice or comments greatly appreciated.

Thanks

Dave​

 

[HLaB]

Different rub but if I forget to use my orthotic insoles, as well as getting sore knees my ankles rub.

 

[Dzzi]

...having had more of a look around i think he is going to need to pay a visit to the chiropodist who made his last set of insoles and discuss the issue with him, i think i'll get him to put his old ones in the next time we are out and see how that works out.