xenologer

Hi
Haven't done too much actual mountain biking; my past mtb frames have been running skinny tires as road commuters and are apparantly 1 size too big for actual mtb use.
5'4", 27.5" cyclists inseam
So following people's advice for propor off road sizing, am trying out a 15" frame.

Now my confusion:
so the frame has a low top tube; makes sense for standover given fat tires.
and it has a high bottom braket; makes sense considering the fat tires are lifting it up, plus ground clearance off road
but this means.... Lots of Seatpost Showing. only about 1" till the minimul insertion mark is left.
So, is that normal for MTB? I gues it kinda makes sense given the physical constraints; but it sure looks wrong from a road persepective.

ColinL

any seatpost insertion more than the minimum is just fine. I always have plenty of seatpost with the shortest ones (350-370mm) but you can buy them at least 410mm.

dexmax

Hi xenologer,

I am just slightly taller than you.
I ride the smallest frames, and on my most recent one -- I even got a women specific geometry bike.. (below)
Personally, the short top-tube and different angle of the seat tube seemed awkward during testing, but after a while -- it was pretty comfortable (more comfortable than my other bikes). But because the frame is smaller that what I usually get, I will be needing a longer seatpost. Right now, on the seatpost that came with the bike, it is on the minimum insert mark.

I'm still setting up, but I think this is a good geometry for me.

pic below

Lexi01

I just bought a 450mm seatpost for a Scott Spark 29er I've ordered (which should be arriving this week!!!!!!!)

It comes with a 400mm post which I'll need to fully extend to set-up properly...I'll just feel more comfortable having an extra 50mm of post inside the seat tube.

ColinL

sure, but that's less surprising given that you are very tall. for the OP, I guess he either has long-ish legs for his height, or he's on an aggressively small frame and could probably ride larger frames.

my bike has 150-160mm seatpost showing above the clamp.

Lexi01

Sounds like your bike is too big...

ncfisherman

Not necessarily. You have to take bike geometry into the equation.

mystolenbikes

Sounds like you are more concerned with how the bike looks than how it functions. but not the worry unlike a road bike mountain bike seat is not set it and forget it. Depending on the terrain and your riding style sometimes you might have adjust your seat five six times during a ride. Sometimes raised high as possible (for climbing) and sometimes slammed to the bottom or anything in between.

ColinL

and the person's body dimensions, especially if any part of them is not in the middle part of the bell curve.

these are the bikes of a person 6'0" with very long arms. I can stand over them no problem. notice the similarity in fit. not same-- body position is way different. but both are properly setup for me.

ColinL

seatbag on the road bike is obscuring the 'oh no too short' seatpost on the MTB. I didn't think of that when snapping a quick pic.

xenologer

In a sense, yes this may be my issue.
I can understand... that functionally a long seatpost is needed due to a combination of ground clearance and standover clearance.
But at the same time, having as much seatpost showing as the frame's seattube is long *looks* scary/weak; as in it looks unsupported and wanting to snap off. Does that not bother more seasoned mtb-ers?

Almost makes me wonder, as far as hardtails go, why not mixte' mtb frames?

Lexi01

To be honest I reckon your roadie is too big too...I prefer a lot more drop from seat to bars than that. But that too depends on the individual, flexibility, age, etc.

Nice bike though - I love a black & white colour scheme. My SuperSix is quite similar.

ColinL

Thanks! It's only 9cm of drop. I think I mentioned before that I have a mismatch in my leg and arm length. I can't get that reach on a 58cm road bike unless I use a 130-140mm stem. If you can standover the bike, it's not too big.

The MTB certainly I can ride an XL (what it is) or L as long as I don't have toe overlap (which almost no 26" would, but some 29ers do).

Lexi01

Out of interest how many people actually do this? I don't...not saying its right or wrong I'm just curious.

And if you do it are you using a dropper post or do you actually get off the bike at the bottom of a hill, grab the allen key, adjust and get back on?

Seems like a great way to ruin a nice ride.

mystolenbikes

Well since most mt bikes come with the quick release seat post collar it only takes seconds to adjust the seat.

I adjust my seat post so often that I got sick of stop adjust and go stuff so I went and bought a dropper seat post and I'm telling you it was the best purchase I made for my bike. Now I have the dropper post I literally adjust my seat dozens of times on the fly during my ride.

Lexi01

Which dropper do you have? I was looking at a few but my LBS reckons they're crap and they all eventually break (as in just slide down to the lowest point under weight).

ncfisherman

Find a new LBS. I reckon they don't have much, if any, hands on experience with dropper posts over the last couple years.

Looks like MSB is running a version of the Crankbrother Joplin, which is probably the most notorious post out there for issues. I've been running a Kindshock i950r for a while now and had a Gravity Dropper before that. I have had zero issues and a lot of issues I have seen(with other posts) have been related to set up. At this point, reliability of droppers has come a long way and issues seem to be few and far between(except for Crankbrothers posts). Like suspension components, they do need to be maintained. If you're not into routine maintenance, a standard post may be best. I do a basic service on my KS every 6 months with a full service every year.

Lew.

I change my saddle height about 4-5 times on Sunday rides. Never on races, unless it's a team effort I may change it when I'm not riding. On Sunday rides I change it, I have it high (approx. height, when heel is on pedal and leg extended) and then for the faster single track I either drop it down to the lowest if I'm not gonna use it or mid height if I am slightly. I *hate* it when the saddle comes and slams me up the arse, not gone over the bars cause of it yet. I don't run a dropper post, personally, they're too expensive for what they are and what my budget allows. My saddle height looks out of proportion in terms of look (Hardtail StumpJumper) when it's on its usual climbing height.

mystolenbikes

Lol. Even if it breaks and slams to the lowest position there is enough seatpost in the frame that you can still lower it or raise itli like a regular seat post.
I have the joplin 4. It's two years old and haven't done a maintenance on it yet.
I know they are not cheap but they are worth every penny. I highly recommend one.

dminor 

I do it all the time. It's worth it to me to take the extra couple of seconds at the top and bottom of a fun and/or long descent to hop off, flip the QR and raise or lower the post.

A dropper post would be ideal but I am too cheap still to buy a good quality one. I had a cheap KS-made one for a couple of years and loved using it but it eventually crapped.

It is my opinion that EVERY trailbike should come stock with a dropper post. Period. It would accomplish two things: transform everyone's ride experience and make dropper posts so plentiful that the prices would plummet to a reasonable level.

ColinL

I have not seen a dropper post on a bike in Kansas in quite some time. I know a few guys that make a few trips to Colorado every year, and I wonder if they use them there.

I haven't been hit in the arse by my seat when descending, yet. But a fast descent here takes 3-30 seconds, and a slow techy one is really slow, rocky, and still takes maybe 1-2 minutes.

dminor 

That's not the main point to using one, really. Having the saddle out of the way on descents allows you to: assume a position that is not perched so weight-forward over the bars; allows your knees to bend more, ready to absorb impact and shift weight; and allows you to shift body position fore-and-aft or side-to-side more readily. Yes you can achieve some of this by getting behind a fully-extended saddle but then you would not be positioned optimally in the cockpit.

ColinL

That makes a lot of sense. I do get behind the saddle, but you have to be pretty high, and you can't bend your knees near as much as if you were over the saddle. Plus it puts your weight way rearward.

Lexi01

Personally, I don't think that's a reason to lol. The fact that something may still be sort of be functional after it breaks doesn't negate the fact that it's broken.