I have never thought I was strangely proportioned but I have been reliably informed my effective top tube length on my bike is too short, I tried an on-one scandal in a bigger size (just to play on as it was all they had in the shop) that felt much better but apparently I needed a smaller frame as the seat post was too low.

So what I would like to know is – what is the best geometry for my apparently weasel shaped body (in terms of diddy legs and long back – not all over fur and buck teeth!). a professional fitting is too expensive at the moment but it’s time for a new bike so I’d like to know it fits.

Heaven knows how I’ve managed on the last one for several thousand miles! 🙂

Why not just try riding other bikes if you want to know if they fit? A theoretical size after trying a frame that was too big for you isn’t a very scientific approach.

https://www.wrenchscience.com

TooTall – I would love to have the time to try all the bikes I fancy – and to actually find the right sizes to demo. The other point was that although both bikes didn’t ‘fit’ they are both ok to ride, I guess I just wanted a bit more of the science behind it.
Thanks for that will have a look

I’d go for a ‘proper’ bike fit with one of the companies that offer it – you’re as likely to get it wrong trying to sort it out online as right, imo.

Bike fit – especially for mountain bikes – seems to be as much as what feels good as what is ‘scientifically’ good. I’ve had wildly differeing results from on line calculators. OK – I’m out there and off most scales but had wildly varied results. They each use different formulas I guess – thats why I steer you to the real world.

I’m not sold on bike fitting for mtbs as they are about more than simple pedalling efficiency of a road user. The last shop I worked in offered bike fitting that was costed against the bike’s price so effectively the fitting was free if you bought a bike there. If you are truly lost in the world of how you will best fit your new bike this sort of service would be worth a look.

Fisher bikes run a relatively long TT for the given frame size. I have a (now discontinued) Ziggurat in a 17.5″ with a 23.9″ TT. Quite/very long for the given frame size.

long TT with On One bikes, and free fitting at the Rotherham shop. Give ’em a call?

apf

I really fancy a 29er for my next bike, but just want to know it’s in the right kind of proportion for me I guess. May see if i can find a local place that offers a good fitting service – and hopefully can sell me the bike I want to ofset it against.

I am loath to sit on a woman specific bike and find out it fits better – as I couldn’t stomach the ‘girly’ paint jobs they chuck on them.

I agree with MTBfix – fitting is one thing with road bikes where you’re seated most of the time and geometry varies less, but throw in handling preferences to the MTB fit mix (ie prefer a slack HA = longer FC that often needs steeper SA = short tt or long wheelbase dilemma) and they’re difficult at best, useless at worst since they’re based on proportional averages anyway.

You could try playing around with bikeCAD – you can model your current bike, measure yourself up and set up a rider the same size on the bike, and then ammend dimensions based on how you think you’d be more comfortable? It’s a simple, intuitive program with a fee online trial. trial and error isn’t the easy way but i’m not convinced a fitting session can do better. Only a few hours on a bike says if you’re comfy. Try something in bikeCAD, then try to replicate that position on your bike somehow.

And if anyone starts off with putting a plumbline from your knee to the pedal axle, stop the fitting session right there! )

Edited to say, you’re the opposite proportion of what would suit a women’s specific, don’t worry! They’re based on a shorter TT and steeper SA generally. You may need an average to slacker SA, shorter ST, a longer TT and maybe a shorter HT. An on-one with a layback post may be ideal for off-the-peg fit, if not it maybe a good excuse for a custom.

For an MTB, don’t worry about “the science”. If you’re happy and comfortable on your bike, carry on. If not, try to figure out what’s wrong and fix it. As other people have said, there are many things that go in to fit, including but not limited to:

riding style
typical terrain
your fitness
your flexibility
preferred handlebar width
preferred standover
preferred handling
average ride time

Almost all these variables are not that variable when discussing road bikes, but on a mountain bike they all play a part.

Who “reliably informed” you? If I had to ask anyone’s opinion on how your bike fitted you it would be yours!

adjustablewench – Member
– what is the best geometry for my apparently weasel shaped body (in terms of diddy legs and long back –

I’m the same – the Scandal is perfect at M.

I also ride an XL Pompino in comfort – my height size should be M. Toptube height isn’t so important on the road. Who cares how much seatpost is showing?

riding style – pass but someone described me as aggressive! made me laugh!
typical terrain – al sorts do commute on my bike, a few hours on singletrack when possible but longer trails and wild camping are my choice.
fitness – fairly
flexibility – very
i’d happily ride all day too, and i guess thats where the curiosity comes into the ‘ideal’ geometry, nothing can take away all the pain of a day in the saddle – but I just want it minimised!

As for who reliably informed me – he is right, as the ways in which it doesn’t fit are obvious