On my road bike my saddle height is 804mm and my saddle to bar drop is 112mm. I find on my mtb that the saddle is far too high at 804 so drop it a couple of inches which seems to work okay, but I’m not sure what to do about bar height.

I started building up my 29er this evening and it’s come to the point where I need to cut the forks. Niner say you should have a max of 40mm of spacers, but then say that you shouldn’t ever have spacers above the stem, so can anyone give suggestions as to what I should do to get my bar height correctly. FWIW, I ride XC.

Experiment!

Presumably the max 40mm of spacers is due to some concerns over over-leverage on the head tube and/or frame?

And tbh my saddle height is dictated by the length of your legs, and then I like the bar as high as I can get it – but due to long legs its still below the saddle.

My saddle is 805mm. I slam my stems on 29ers with 20mm rise bars.

experiment… and why no spacers above? It looks a bit gash, but certainly allows plenty of playing around. Remember you can never add on to the steerer after it’s cut, so it’s worth experimenting.

If it’s your first 29er, then even more reason to experiment.

I know it’s me being a pussy and it’s probably unnecessary but I have Niner forks and the manual says

• Do not exceed 40mm spacer stack height.
• Do not place spacers above the stem. The stem must clamp the area reinforced by the compression adjustment plug installed in step 5.1

Which logically means that every time I want to adjust my bar height, I have to cut the steerer.

But yeah it’s my first 29er and my first brand new build MTB so I kinda wanna make sure I get it right, but am worried about experimenting in case something happens to the forks.

804mm from where?

bear in mind that the bottom bracket is higher on the mtb so the measurement you should use is from centre of bb to the top of the saddle.

804mm is centre of BB to centre of saddle, following the line of the seat tube/post

Firstly, (assuming same crank length and pedal/shoe height) if your saddle height is 2″ lower on your mtb you either have your road saddle too high or your are choosing to lose out on sat down climbing eficiency on your mtb to aid control/confidence. (consider a dropper post for the mtb if this is the case)

Bar height drop on your roadbike is massively irrelivent to your mtb bar height, for one thing your road bars will be far narrower and you’ll hopefully have set them up for comfortable/efficient positioning while riding the top/hoods and drops.

Set up your bar height on your mtb so that it offers the optimum control while standing up rather than sitting down.. as soon as things get interesting you should not be sat down.

Right if it blows up then thats how you fitted it.
Now that bit is out of the way experiment. This is the great thing about mountain bikes there is no right or wrong just what works (except singlespeeds)

Right if it blows up then thats how you fitted it.
Now that bit is out of the way experiment.

This – just ride it round roads & gentle off road at first if you’re worried.

Isn’t that with Niner assuming you’ll be using carbon forrks with a carbon steerer which might actually need that support from crushing.

If you’re running sus forks with an alloy steerer I’d say spacers above are okay. Certainly for trying out the position.

Firstly, (assuming same crank length and pedal/shoe height) if your saddle height is 2″ lower on your mtb you either have your road saddle too high or your are choosing to lose out on sat down climbing eficiency on your mtb to aid control/confidence. (consider a dropper post for the mtb if this is the case)

I trust my bike fitter. I ride with my toes pointing down which means my saddle needs to be higher than if I rode with a flat foot (does that make sense)? Because of that I choose to run my saddle lower on the mtb to help when I might need to unclip, I can’t put my feet anywhere near to flat on the floor while still sat on the saddle on the road bike, on the MTB I have it so I can at least get some traction from them if I need to.

A dropper post is definitely on the cards at some point, but I’ve just put the best part of £1750 on the credit card to build this and a dropper seems like a bit of a luxury item right now.

Right if it blows up then thats how you fitted it.

I wish I could afford to be so blasé!

Isn’t that with Niner assuming you’ll be using carbon forrks with a carbon steerer which might actually need that support from crushing.

If you’re running sus forks with an alloy steerer I’d say spacers above are okay. Certainly for trying out the position.

It’s a custom On-One Lurcher setup rigid, the forks are Niner.

Ok. fair enough then that makes a little more sense but 2″ difference still seems excessive..
Also, is it not a little odd riding (training?) with one pedalling style on the road and a completely different one on your mtb?

I ride with around 40mm saddle height difference between my mtb and roadbike but I only ride flats on the mtb and only ride clipped in on the roadbike, if I were to ride clipped in on my mtb I’d raise the saddle at least an inch for climbing efficiency.

actually, forget everything I just said..
Even if you run the same length cranks on both bikes there’s almost no chance the height of your road pedal/shoe combination will be the same height above the pedal axle as your mtb combination so BB-saddle height measurement is pretty pointless.

You’re over-thinking this, and also trying to translate road bike measurements to a mountain bike. The two bikes are very different, and hopefully you’ll also be doing different types of riding with them.

You mentioned that on a mountain bike you drop the saddle a couple of inches. What’s your existing mountain bike set up like? What bike is it? What sort of riding do you do?

If you are worried about spacers and stem position, bear in mind that you can use higher rise stems and different rise handlebars to tune the fit, and also flip the stem – you’ll have two different positions that way. Stem length will also be a factor. Basically, there is plenty of scope for variation by simply trying different bar and stem combinations.

Bear in mind that On-One tends to go for a slightly longer than average top tube. Your Lurcher is the same as my Scandal 29er (I ride a size small, and it sounds like you’re more M or L sized), and the recommendation is for a 50-70mm stem. With Rebas, a 60mm stem with one 5mm spacer underneath and flat bars, the position is perfect for me. Maybe try a cheap stem in the 50-70mm range (or whatever is recommended for your Lurcher size) and then try different riser and flat bars to see what works for you.

By going the carbon steerer route, you are rather limiting your options to get the right fit. Why not consider buying a cheap second hand pair of rigid steel forks the same length, and get the position right on those, then cut your niner forks to fit once you’re totally confident? Probably a bit academic – I imagine with all that lovely kit begging to be built into a bike you just want to go and ride it. 😉

Just remember – you can always cut a steerer down, but you can’t add more back on to it.

Appreciate the in depth reply, thanks mate.

My longdistance HT has a saddle to bar drop of 2.5cm, my FS has 4.5cm. I can ride the HT for 8hrs without pins and needles, the FS starts to get uncomfortable.

I’d caution thinking something is right based on a short ride.

I like em the same height or close.

I can’t put my feet anywhere near to flat on the floor while still sat on the saddle on the road bike, on the MTB I have it so I can at least get some traction from them if I need to.

Eh? If in the saddle there is no way your feet should be anywhere near the ground.

Your saddle should be at a height that the heel of your foot is flat to the pedal at its lowest point.

Good spot, b r. John, near in mind the pedalling dynamics are the same. A low saddle will cause leg pain. Unless you are mostly riding dh or jump / pump stuff – and you have bought an xc bike, so I am guessing not – then you will want to have your post at the right height once you and feeling more confident off road.
SAddle and stem relative height are dependent on bike geometry, riding style, terrain and the flexibility and core stability of the rider.

Would nip into your local mountain bike shop and see if they will do a fitting for you. As it sounds like you have been shopping on teh internetz, you should be prepared to pay for this advice – it’s only fair. Looks like you are in Bristol, so try Mud Dock.

Thomson state you must have a spacer above the stem otherwise the whole clamp area of the stem is not round the steerer. Makes sense to me and I always have 5mm above.