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stoker stem 250mm ctc

Mark Tipping2026-02-01 11:17:07

I have tried ebay etc but the only available bits are in the USA and I am less keen buying from there these days......

I am after a stoker stem basically the same as the co motion one fitted on our non electric tandem, to go on our new to us "assisted" tandem.  It needs to fit 27.2mm upwards diameter seatpin, and have 250mm centre to centre (to the handlebars), preferably 31 OS bar fit but I can work with 25mm if that is what is available.

Stuart Hibberd2026-02-01 15:16:01

I use the Thorn Stoker extension, unfortunately it is no longer available in 170 or 220mm. only available in 120mm it seems.

You can just add the ahead stem of your choice to get the extension required.

This 145mm stem would get you to about 248mm extension maybe.

https://www.ebay.co.uk/itm/127098197336?var=428219243829

 

 

 

Jamie Gray2026-02-01 19:30:34

Hi Mark, 

you will need to shim the seat post from 27.2 to  the correct stem steerer 28.6mm using a USE shim 

https://www.use-components.com/products/27-2mm-i-d-shim?_pos=1&_sid=b644fe672&_ss=r

it's works and is a cheap solution to using road stems on a seat post. 
cheers. 

Mark Tipping2026-02-03 23:12:23

Stuart, 

Thanks for your input, my fault for not being specific about my requirements.  I fit a Carradice super C saddlepack under the stoker stem on our tandems which with a racktop bag and a barbag (for valuables to unclip and take into cafe) means unless grocery shopping while on tour or severe winter we never need a pannier on the side.

This means I need a stoker sten fitted immediately undet=r the saddlle at the top of the steersmans seatpin, to give clearance for the bag.  A poor pic below of the tandems we have with them fitted to illustarte the fitment.  The middle Co-motion tandem has the sort of stem I have seen on ebay in the states and at 250mm long would be ideal.  The far blue Lee Cooper tandem with red bags has an SJS two p[art stem fitted, the type you are using one half of.

From your photos getting room under the stoker stem for the bag would not be possible using standard stems as you have.

 

The Gepida nearest camera has the odd "euro city bike of gas pipe construction" style so there is no room for such a bag. My idae is to use the 250mm long stem exactly as on our co-motion and discard the existing stoker stem arrangement, this will create room for the saddlepack.  As the racktop bag on the Gepida is permanently filled with a second battery the need for extra room is paramount, we have become accustomed to the storage capacity of the three bags in combo, so will happily make adjustments to acheive it.

Available stem from USA on fleabay which I seek this side of the pond:

https://www.ebay.co.uk/itm/168063249374