stem advice

mroli

Hi guys - I was just wondering if people could give me some advice on a stem that I am going to buy for a new frame that I am building up. I am trying to keep the new frame (to be used for bad weather riding/winter/possibly light touring) as close to my current bike (racing/sportive riding) as possible (ie same width handlebars, contact points etc).

I was measured for my exisitng bike - it has a 55.5 top tube and I have a 12cm stem on it (rear stays 40.5, seat tube 55, stack 30cm). The frame that I want to build up is identical in size except it is 2cm longer in the rear stays, 1 cm shorter in the top tube and 1cm longer in the head tube.

The idea is that it will give me a slightly more "relaxed" ride (and take mudguards for winter etc) - but what size stem should I go for? Obviously as the top tube is shorter and the head tube is longer, I will be more "upright" with the same size stem and I guess this is the point - or will that be sorted out with the higher head tube and should I go for a longer stem to keep "stretched out", but the higher head tube giving me a more upright position naturally? Or should I even go for a shorter stem to ensure the upright position is maintained?

I'm sure that this is really down to personal preference - but if you have any tips, please let me have them.

Thanks a lot

LazyLoki

The chain stays aren't really relevant in this case and I would stay that the 10mm increase in head tube isn't enough to effect your overall reach much.

The only thing I would worry about was the length of the top tube. However, check the seat tube angle also as this affects the reach of the frame. One degree increase in seat tube angle will increase the effective top tube 'fit' by 9mm. So for example, a bike with a 73deg STA and a 540mm TT would have virtually the same overall reach as a bike with a 74deg STA and a 530mm TT.

Then just change the stem length accordingly so if the new bike works out to be 10mm longer than your current then go for a 110mm stem. And just to throw another spanner in the works, if you change your handlebar model, make sure you get one with the same reach/drop as your current ones if you want to maintain fit

sandbag

Just go for a shorter stem. You will know the position you want from your previous frame. The new frame 1cm shorter so adjust accordingly. If you still can't decide at all then go for a adjustable stem. Have a play with it, then when you know the position you want, change to a fixed stem of that length. You keep the adjustable stem for the future, as a guide for new frames

I follow this pseudo law, for my comfort and fit.

When you look down, whilst in the drops. The top of the handlebars are blocking the view of the hub. The amount of reach then feels right for all hand positions.

A 100mm stem and sliding the seat forward. Later i got a layback style seatpost. Luckily i could just slide the seat abit further forward to it's limit, to maintain the same fit.

Also need to experiment with the best position for your knees, using the saddle. Directly over, slightly in front or slightly behind the pedal spindle, which i find better for climbing when sitting.

mroli

Thanks guys - that's a great help.

The seat tube angle is the same, so that isn't a problem (thankfully).

Point noted re the handlebars - hadn't thought about that, but that makes perfect sense. TBH I don't spend a lot of time in the drops, but a good point.

Point regarding the seat position re cranks noted too - I know my ideal seatpost height, but obv need to make sure the position matches.

Adjustable stem tip is great - will have a look for one - thanks again guys.

M