Bike Size

[Romulus]

Hi,

 

I am brand new to mountain biking. My wife bought me a 2012 Scott Spark Team (dual suspension) a few weeks ago. Prior to this I haven't been on a bike for at least 15 years. I was never into cycling, the only cycling I ever did was messing around with my BMX as a child.

 

After receiving this splendid gift I hit 3 trails and fell in love with mountain biking.

 

I'm 1,80m tall and weigh 89kg. I went to a bike store to have a proper bike set up and fitting done and was told that I need a large frame and the medium frame size which I currently have is too small. This is despite the bike having a 400mm seat post with the seat on the highest setting. I was also advised that should I continue riding this bike, I may end up with a problems such as back ache, neck ache, knee issues and even wrist problems. I was also told that I'd be using and developing the wrong muscle groups in my legs and when I finally buy a bike that's the correct size (large), I may feel weaker and not ride as well due to riding a bike that's too small.

 

I am a complete novice but I have to say that after the bike's settings were changed to be more accommodating to my body, it feels much better and I feel completely comfortable on it.

 

Can you please advise me on the following:

 

1. Can I get away with riding a Medium?

2. I am aware that if I sell my bike I'd lose money, despite the bike being almost new and in perfect condition, as it's now a second hand bike. Should I sell the bike and buy a cheaper bike such as a Scott Aspect 10 29er?

3. Is frame size really such a big deal? It seems that I'm just too big for the medium but not by much.

 

Your advice is appreciated.

 

Thanks.

[M L]

I am 1.86m and started off on a Medium, then upgraded to a large, and it didn't feel so lekker. Bike didn't handle very well so later I upgraded again, now on a medium 29er.

 

I normally don't trust any advice given to me by bike shops. I also don't trust all the measurements and fitment advice on the internet. I don't follow strict rules, climb on the bike, ride it and adjust the seatpost height, spacers on stem, stem length according to how YOU like it. If you like how it feels and handles then I wouldn't change a thing.

 

If you feel it is too small (bike frame sizes differ in top tube - length from the seatpost to the stem, and seat tube length - length from the bottom bracket to the seatpost hole), then the best bet is to sell the frame and buy a second hand frame alone. That will cut the costs lost to a minimum.

 

Do remember that when you pedal and either one of your feet are at the lowest point there should still be a small bent in your knee. It shouldn't feel as if you are stretching your legs to pedal.

[Romulus]

I am 1.86m and started off on a Medium, then upgraded to a large, and it didn't feel so lekker. Bike didn't handle very well so later I upgraded again, now on a medium 29er.

 

I normally don't trust any advice given to me by bike shops. I also don't trust all the measurements and fitment advice on the internet. I don't follow strict rules, climb on the bike, ride it and adjust the seatpost height, spacers on stem, stem length according to how YOU like it. If you like how it feels and handles then I wouldn't change a thing.

 

If you feel it is too small (bike frame sizes differ in top tube - length from the seatpost to the stem, and seat tube length - length from the bottom bracket to the seatpost hole), then the best bet is to sell the frame and buy a second hand frame alone. That will cut the costs lost to a minimum.

 

Do remember that when you pedal and either one of your feet are at the lowest point there should still be a small bent in your knee. It shouldn't feel as if you are stretching your legs to pedal.

 

Well, you're taller than me and if you're riding a medium then I suppose that I could stick to my current bike. I don't want to sell this bike, I really love it and so far I feel comfortable on it. I've also noticed from most people on this site that people who ride for years and take it seriously are continuously upgrading to newer models etc. Do you think it would be fine for me to simply keep this bike till I'm ready to upgrade to something better in the future? Thanks for the advice.

[Pieterg]

If it feels good ride it make sure you don't have any pains any where.

[Cippo]

Have a look at the Ergofit vs BG fit thread here in Tech QA. Grab one of the numbers for technicians and book yourself a proper assesment and bike set up. I personally went to Dr. Swart but had to wait for an appointment. There are other really fitters around. There is a guy that travels between town and Northerns and comes highly recomended as well. Owen at Cyclelab Winelands at Somerest Mall also does Ergofit. Its R550 for an Ergomax fit but well worth the money to make sure you setup properly made the world of difference for me on roadbike especially over long distances. They will advise you as to next step. Explain to them your situation and they can work around it. Good luck

[Cippo]

https://community.bikehub.co.za/topic/114842-ergofit-setup-agents/

[davidlangebaan]

ERGOFIT +1

Renay does the setup at Epic Bike shop in Plumstead.

I'm 1.81. I had a medium that killed my back because the top tube was too short.

I'm now on a large with a longer stem and am really comfortable.

[Grondpad]

I have to agree with Super Mario. First get the proper bike fit. They will most likely be able to get you a perfect fit with only small changes (like seatpost and stem). I am 1.81 and the bike shop recommended a medium for me and after about 6 months I upgraded to a large and I have to say it fits me better. But remember that the large from one brand differs from the large from another brand.

[Thomo]

Unfortunately bike sizing isn't as straight forward as "I'm 1.8m so should ride a ?".

It's affected by bike geometry, rider fitnes, body make-up etc.

Having the saddle post extended to 400mm suggests that the bike is probably too small - but that's not to say that you can't ride it without any issues.

Most people can fit on a range of bike sizes and make them fit with the right length stem, seat post etc.

[JTK]

I think you could get away with either. Also bear in mind a medium GT is like a small Giant. So suppose it depends what bike you have as well. He could be right. As for now I should be riding a medium but I ride a large as I like the stem nice and short and I am shorter than you. But I do realise technically speaking the bike is too big for me. Maybe tell us which bike you have as the sizes differ. A trek is also smaller than a giant for instance (my experience anyways) I have a good mate that races religiously. He is 1.8 and rides a large anthem. He got on my large Trance and got off immediately saying it is set up too small for him So you can make what ever you have fir in reason if you within reason of course. A XS GT will never fit Vic Matfield

 

as to the knees. seet position forward and back and seat height. Here I doubt that, given your length, the bike is too small. Maybe just do the plumbline test to see if your seat is in the right spot forward and back. You can go lower in seat height to a degree and get away with it. It is just less efficient but wont fook up your knees. So again. I cant see the issue. What length stem is on the bike as well? That could also have a impact. A friend of mine once told me (also an avid mountain biker) that if you ride your bike and sit comfortably and look down your handle bar should blank out the front axel. Then it is size wise at least set up nicely for you and the balance should be good as well.

[RockCoach]

I wouldn't worry too much. I fitted a lady on a Scott Spark this week and saw how flipping long that top tube* is on a medium frame. She was fairly tall (1.7x m) and the bike had to have an ultra short stem with major rise. I had to set the saddle almost all the way forward to get her anywhere near comfortable. That frame was too big for her which is much more of a problem than too small.

 

* top tube length is the most important measurement in frame sizing.

[geecee]

im 1.8 on a medium, no issues but i do feel a little cramped sometimes.

but i worry more about aiming my bike downhill and hoping for the best, not 2/3 hours in the saddle/

 

take the above advice, ergofit etc. best thing to do. you may get away with some smaller changes than a frame change

[Eugene]

There is a rule that you can settle for a one size smaller, but never one size bigger. So, if you are supposed to be on a large frame, but are riding a medium. It should be fine.

 

many pro riders choose a frame size smaller than they are supposed to have. They say it makes for a more nimble, responsive ride.

 

If you are comfortable, stick with it.

 

I've never checked the geometry myself, but I've been told that Scott frames are generally on the big side anyway.

[Madmac]

Whatever you do, don't change the wife!!

[Romulus]

Wow, I'm really grateful for the advice and responses. Someone asked me about the bike I have - it's a 2012 Scott Spark Team 29er, MEDIUM with a 400mm seat post. Please click on the link to see a picture of the bike http://www.scott-sports.com/us/en/products/221701/spark-29-team/

[Clinton1]

As most know you can measure absolutely every body part in deciding which bike suits you best but as a quick overview I quite like this site:

 

http://www.ebicycles.com/

 

I'm 1.88m and it suggests a 20" bike but does say I could get anything from 19" to 20.5". A 19" was on special so I got it and it seems fine for me. 19" would normally fall under large as far as I am aware.

Edited June 22, 2012 by Clint_ZA