Road cyclist wanting to get into MTB

Alibran

I've been into road bikes for a few years, but I've just moved to a place where there are some really good natural mountain trails nearby, and I'm not sure what I need from a bike to make use of them.

I already have an 18 month old mountain bike, but tbh, I'm not sure if it's suitable or even big enough for me. I live in Spain, and when I bought it didn't have much knowledge of spanish, so pretty much just went along with what the man in the shop recommended. He "fitted" it for me when I went to collect it, and I realised there was a problem when he adjusted the saddle height so I could get both feet on the ground!

Anyway, the bike I have feels small. I've adjusted the saddle as high as I dare, but there isn't much seat tube left inside the post, and it still isn't as high as I'd like. It's a women's specific model, and the reach to the bars feels very cramped (although I may be comparing it to the stretched out position of my road bike, which is also women specific, so isn't *that* stretched out). I've positioned the saddle as far back as it will go, and when I stand on climbs - to avoid putting too much strain on my knees because the saddle isn't high enough - I'm worried about hitting my knees on the bars.

The trails I'm hoping to ride are quite steep in places, mostly hard-packed with a thin top layer or loose gravel or sand, with large stones and smallish rocks either embedded in the hard surface or loose all over it. There's very rarely any mud, even after rain, because the surface drains well. I've taken my MTB up there, and it feels awkward and incredibly hard work on the climbs, and I'm not as far back as I'd like on the descents, even when I hang over the back of the saddle.

So, my question is, is there anything I can do with the bike I have, or should I look at buying a new one?

The bike I have has a 13.5in seat tube, not particularly relevant except that I'm assuming I was sold the smallest size. I am 5ft3. The top tube is 21in and very steeply angled. I don't know what the vertical measurement would be because I'm not sure which points to measure between. The stem is very short - no more than 2in - and the bars bend back slightly towards the ends. It cost me €260 (about £230 at the time), so it's very much an entry level bike.

Is there anything I could do to it to make it a better fit for me? I'm thinking of a longer stem and seat post - if a longer seat post would be safe. Or would I be better off buying a bigger bike? I have up to £500 I could spend, but there are also a lot of other things I could spend it on, like some new gear, hydration pack, spares, etc.

I just really want to go exploring the trails on a bike I can have fun on!

tri-sexual

what make/model of bike is it?
dont confuse the fit of a road bike to that of a mtb,
modern mtb are generally more upright, this allows better control of the bike when the trail gets rough, a short stem is also more common, this allows better more precise steering than that of a longer stem.
as a simple rule concerning fit is to straddle the bike with your regular riding shoes and check for clearance between your crotch and the top tube, you should have at least a couple of inches clearance.
more precise fitting is possible, and a better fit can be achieved with different components, ie stems, hadlebar widths, crank lengths etc
if the bike is ok, take it out and ride the trails, change components as neccessary if you feel discomfort or think that different components may be of benefit.
if you do decide to buy a new bike ask for advice from several different sources and bike shops. seeing that you are a relative novice to bike fitting, make sure that you get a bike that fits you rather than being sold a bike which just happens to be in stock.
test ride as many as possible before parting with your money

Alibran

Thanks for the reply.

It's a BH Over-X. (BH is a spanish make, and they're hugely popular over here.) I did a search on Google, but couldn't find any pictures. There's a man's version on Wiggle, at a much higher price than I paid for mine, which is probably partly due to inflation, but also because spanish goods are generally sold MUCH cheaper in Spain than in the rest of the world.

I have a couple of inches clearance when I stand over the top tube - I certainly wouldn't want less after I landed hard on the top tube of a bike I hired in the New Forest a few years ago, when OH just stood there laughing and told me I was lucky I wasn't a bloke!

Anyway, that suggests I wouldn't want the same bike with a bigger frame ....

My biggest concern right away is not being able to get the saddle as high as I want. When I first got into cycling, I injured my knees by having the saddle too low - I wanted to touch the ground - and have since gone with having a straight leg when I put my heel on the pedal in the lowest position. I know it's considered the least accurate by road cyclists, but it works for me. I'd like to do the same on my MTB if I could. Would this be considered too high by experienced MTBers - it would put the saddle about level with the bars, and I'd have around 27cm of seat post exposed - or doesn't it matter as long as you're comfortable?

Yes, you're probably right that I'm confusing the fit of a MTB with a road bike. I'm trying not to do that, which is why I'm asking here rather than assuming I know best and trying to set up a MTB the same as my road bike, but it's hard not to compare with what I'm used to. I'm also aware that some of my "problems" are probably down to not being familiar with the different style of riding, and they might go away on their own with practice. I just feel like there are issues with the fit of this bike that I need so sort one way or the other before I can enjoy the practicing!

tri-sexual

BH bikes are actually pretty good bikes
how much higher would you like your saddle to be?
if its not too much over what you have at the moment, you can simply get a longer seat post (a few inches), if you need a really long seat post then it may not be suitable since the extra length will put additional stress on your frame's seat post but dont think that it would be a problem since you are 5' 3"
if you are trying to get the same fit from a road bike as a mtb bike (the stretched out fit)then you will not get the best from your mtb when you are off road.
even my mtbs are set up differently depending on their uses, xc race is set up with higher saddle but all mountain mtbs have a lower saddle.
if you really want a new bike, then JUST DO IT

Alibran

I don't want a new bike enough to waste money on something I don't need if I can get the one I've got to do the job I'm asking of it - if that makes sense. And it's not like I'm going to be doing anything particularly technical.

The saddle doesn't need to go up much. I've just measured from the top of the saddle to the pedal in the lowest position, and it's only 2in different to my road bike. It feels like more, maybe because the saddle's a different shape.

Ah - maybe that means I can buy a new saddle as well

I'll take a look at some seat posts on Wiggle. Is there any particular make you'd recommend, or doesn't it matter?

ddraver

Should nt be posting here really, but if you can't get the saddle up high enough that does suggest that the bike might be too small. Road and MTB saddle hight should nt be that different (maybe an inch lower for Trail riding), but you should be able to set it at the right hight for pedalling on tarmac.

But you should be able to get even further off the back on a bike that is too small for you so maybe you need a shorter stem (or, no offence, you need a bit more practice). I don't know the model but if it's typical euro style then it might be an XC bike which are longer than standard trail bikes, But nowhere near as long as a road bike.

You could try a longer seat post as an easy fix.

Alibran

Thanks, ddraver. Yes, a longer seat post is what I'm going to try first, since it's a relatively cheap option.

I don't think I explained myself properly when I said I'm not as far back as I'd like on descents. I should probably have said, I'm not as low as I'd like. Yes, I could get further off the back of the saddle to get lower, but I'm reluctant to do that because it would shift all my weight back, and I'm assuming I need to keep a fair bit of weight on the front wheel for grip when braking.

warpcow

Alibran wrote:

it would put the saddle about level with the bars, and I'd have around 27cm of seat post exposed - or doesn't it matter as long as you're comfortable?

^this (up to a point). On my 3 MTBs, 1 has the saddle level with the bars, another about an inch higher and the other about 3 inches higher. It all depends a lot on the type of bike and its geometry/intended use. Based purely on your description here, it sounds like the bike probably is the right size, you're just not used to it yet. Contact points such as saddle/seatpost and bar/stem/grips will allow you to fine-tune the fit somewhat and generally make it more comfortable.

When descending you'll be safer with the weight further back. You're only looking to control your speed, not stop dead. With your weight too far forward on a steep slope there's more chance an obstacle (stone, root, etc) will launch you over the bars before you've even had time to consider braking.

One thing to note is the the minimum insertion mark on the seatpost does not necessarily go for the frame too. Generally speaking you want at least 2 inches of seatpost below where the top-tube joins the seat-tube to avoid putting any undue stress on this area.

Alibran

That makes sense about the weight being positioned further back. I forget I don't have to react to things like pedestrians and idiot drivers on the MTB. And I have noticed that I have to go very easy on the brakes on the loose surfaces.

I pulled the seat post right out today, which I'd never done before, and noticed how little there was past the minimum insertion mark. I'd just kept moving it up and up until I reached that mark, so it probably hasn't been terribly safe for a while.

I've found a seatpost on Wiggle that I think might be suitable:
http://www.wiggle.co.uk/fsa-sl-280-seat-post/

The seatpost I already have is slightly set back, and I've got the saddle as far back as it will go, so I figure this would give me a bit more room for adjustment if I need it.

I measured the diameter with a metal ruler (best I have) and it looked like just over 27mm, so I think it must be 27.2, seeing as that seems a pretty common size. But I'm not so sure about the length. Is it measured to the join between the top of the post and the head, or to where the fixings attach to the saddle rails?

I need about 250mm above the seat tube (measuring to the join), so I think I probably need the 350mm length, leaving 10cm/4in inside the seat tube. Does that sound about right?

ddraver

Is it written on the post somewhere? 27.2 is a pretty common size

The weight back thing is just practice, There is a balance between being the right amount back to let the bike roll down steep hills and moving forward again to steer. There is no one correct position, you have to be constantly moving...

The good news is that practising the technique is the fun bit if you already have the engine from road riding so get out and enjoy! 8)