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I've see a couple of posts saying it's better to buy a too small bike and extend your cockpit / effective top tube than it is to buy a size too big and try and reduce it as a shorter stem can make the steering too sensitive ... does anyone know if that's so and if it's a very noticeable effect.
I tried a bike in medium at a shop and they thought I'd be better off with the small and certainly the reach felt too much, there's a 2nd hand medium for sale though at a very attractive price and I'm tempted to get it and put a smaller stem on .. the difference on the manufacturers site between the two is 540mm vs 550 mm so theoretically only a 10mm shorter stem.
Does anyone have experience of this and can advise one way or the other??
I’d always do bigger frame short stem, assuming a similar stand over height, as a short stem fits well with wider bars
A shorter stem makes the steering a bit twitchier, but if you then put on longer bars that will compensate? And also you probably won't notice anyway after about ten minutes.
I think having had both frames that are too short, and frames that are too long, I'd try to get one that's about right. There are plenty out there.
lots of (pro & wannabe) roadies like small frames with massive long stems
don't think that's a goer on a "modern" geometry mtb though
I've been edging up through the ETT lengths, I'd much rather have a short stem and be comfortable on the bike
Depends on the way the bike is setup that you tried.
Shorter stems and long bars are very much the vogue in MTB’s and have been for years now. A 70mm stem these days is crazy long and most gravitate towards the mid 700’s as a good starting place for bars.
How you will use the bike has a huge impact. If you intend flowy singletrack descents or seeking out steep stuff to throw yourself down then seated positions are secondary as their only purpose will be to make climbing easier. You’ll definitely want to look at long top tubes and short stems in this situation. If you plan more modest riding and intend to be seated mostly with mild descents then prioritise the seated position (and old skool road geo mostly applies)
Road geo is considerably different.
Anecdotally, I’m 178cm and usually bang on the split between medium and large for most frames. I’ve regretted every ‘large’ I’ve ever had and much prefer medium with a lot of seatpost (droppers have a big impact here as you can run a high seatpost and get rid of it at the touch of a button). My CX bike is at odds with this, I have a 54 which ‘should’ be too small for me but feels like a rocket ship and I love very much. The 58 felt like a barge.
If the bikes you sat on had 70mm or so stems then you have around 35mm you can lose fairly cheaply. If they have 50-35mm stems they’re already about as short as they’re getting. I don’t regard stand over as relevant except for kids or maybe commuter bikes, personally.
If it makes a difference what the bike is between MTB / Road Bike it's one of these if that helps ??
https://www.giant-bicycles.com/gb/toughroad-slr-gx-3
I'm very much a medium sized rider but recently went for a large. It was a good enough price to gamble with and a taller friend who had owned a large said they sized up a little small.
I feel pulled forward a little in some circumstances but most of the time it feels right. I'm going to try a shorter stem and see how it goes.
ETT on a mountain bike doesn't really matter, what matters are two things: Reach and Stack.
Reach is the distance from an imaginary line draw straight up from the bottom bracket, then a line drawn parallel to the top of the stem. This gives you a comparable figure between bikes that allows you to understand how far you'll have to reach to grab the bars when standing - really important when descending.
Stack is the distance from the floor to the top of the stem, this figure gives you a comparable figure between bikes that allows you to understand how high the front end of the bike is.
These two figures together give you a really good way to understand if a bike will be a good fit.
ETT is the static distance from the saddle to the bars, this figure allows you to understand how long a bike will feel when sat down. The problem with this is that as soon you you out a seat post on the bike and move it up or down, this figure changes, as the angle of the seattube isn't 90 degrees. So this figure is largely pointless as a bike fit measurement.
With modern geometry you *should* be able to gaurentee this is just sorted. What's more important is you get Reach and Stack right, and then the Seat Angle is steep enough that the saddle is pushed forward on the bike so you're quite far forward when sat pedalling.
How tall are you, and how long are you arms and legs?
Don't make a bike fit, get a bike that fits
I was a fully paid up subscriber to the small and 'chuckable' school of thought for years. Finally decided it wasn't working and newest bike is a longshot cotic BFe in large. And goddammit it fits me so much better than previous bikes. I think some wider bars would probably make it even better as have 720 at the mo with 35mm stem.
Am 5,11 and a gnats cock so always been (I thought) borderline m/l.
Stack is the distance from the floor to the top of the stem
As I understand it, it's to the top of the headtube. This is kinda useless because you can move the bars up or down by fitting spacers under the stem, using a stem with more rise or negative rise, or using riser bars. Because the head-tube and seat-tube are not parallel, the effective top tube length will vary between a short rider and a tall rider for the same bike, but the same thing will happen to the effective reach because a longer steerer will move the stem and bars backwards in relation to the pedals. Reach alone will not guarrantee good fit, just like ETT won't.
I think some wider bars would probably make it even better as have 720 at the mo with 35mm stem.
From a total cynic with a recent Solaris Longshot and the Cotic 'OEM' bars (£30 ish) - get some 800s, its a revelation.
I’m 5’7 with inch inseam of that helps
Standover might be an issue 😉
“This is kinda useless because you can move the bars up or down...”
Stack height matters because it tells you how much bar rise and/or stem spacers you’ll need to get to your preferred fit - and if the stack height is too high you can’t go lower but if it’s rather low you’ll lose reach as you go higher (about 4mm reach for every 10mm of extra rise added).
If it makes a difference what the bike is between MTB / Road Bike..
Yes, makes a big difference. ime the guidelines for one don't cross over to the other much and it's mostly down to how much weight the front end needs for good handling and fit. An MTB almost can't have a too-short stem, a road/drop bar bike certainly can.
Stack id from BB to headtube. Important to me as a fully signed up stem slammer.
Most of my bikes have slammed stems and in the past i've cut a headtube down. I don't like high front ends. Sizing up always leaves me too tall at the front and therefore uncomfortable.
EDIT: after chopping the headtube on the bike - several stems and sets of bars later, I sold it as I still couldn't get it to fit.
540mm vs 550 mm so theoretically only a 10mm shorter stem.
it's 10mm to get to
certainly the reach felt too much
so you need to take 20 mm off minimum. so that means 70 mm which is about as short as I'd expect to see on a road bike. [Exceptions with short stems, wide bars, and slack geo aside]
you could fit a short bar but you're only going to find 5 mm or so.
Longer reach isn't a magic bullet - depends on the trail. I have a medium Mondraker Dune with a 470mm reach which is super fast at bike park wales and in the Alps etc due to the increased stability of the longer wheelbase. I also have a shorter 438mm Liteville 301 (this is actually a large!). On my local trails which are steep and tight the Liteville is significantly the faster bike. The Mondraker just cant get around the turns quick enough.
Its not that longer bikes don't like corners but there is a cut off...The Mondraker is quicker right up until it meets a corner of a certain radius....then shorter bikes kill it.
So basically it depends how tight your turns are - and if you like to ride everywhere then you need to go N+1 🙂
As I understand it, it’s to the top of the headtube. This is kinda useless because you can move the bars up or down by fitting spacers under the stem, using a stem with more rise or negative rise, or using riser bars.
Lol, yep, long post - not stem, top of head tube.
As other say, it matters because it's what ETT and reach are measured against. And it can severely affected how long a bike feels.
A bike with the exact same dimensions, but a 550mm stack vs. a 600mm stack will be a lot shorter if you're a little bit tall and need to add spacers. This is worse with a slack head tube, as you add spacers the effective reach and TT reduce as each spacer you put on top of the headtube will bring the bars just that little bit.
You need to take Reach, Stack, HA, and SA into consideration when looking at fit. One on its own doesn't tell the whole story.
That's way demos are important, as it's pretty difficult to get your head around unless you spend time to research and be bothered to understand the mechanics.