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-   -   Is my bike to big? (http://www.bikeforums.net/general-cycling-discussion/402247-my-bike-big.html)

Random Rider 03-29-08 02:37 PM

Is my bike to big?
 
I am about 5 '10 on a 51 cm bike. Is that to big. When i am one my seat i can only touch the ground with both my toes. Is that the way it should be?

bike_boy 03-29-08 03:07 PM

If this is a road bike, some general things to consider...You should have at least 2 inches of clearance over
the top tube whe standing over it. (off the seat, feet flat on ground) If I am seated and unclip and stop,
I have to lean bike about 3 inches to one side to allow my unclipped foot to sit flat on ground.

I know a rider that's 5'6" on a 54 cm road frame and a 6'2" rider on a 60 cm road frame.
Of course top tube and arm length play a role, too per frame size.

Also, with feet on pedals and pedals at the 6 & 12 o'clock position, your knee (on lowest pedal) should be slightly bent. with arms resting on handlebars, eblows should not be locked.

Considering seat & handlebar and stem heights along with frame, the height of most seats will look like they
can sit just above the handlebars when viewing from the side.

StephenH 03-29-08 03:10 PM

Actually, that sounds about right. But the more important question is whether you like it. It's also partly a matter of seat adjustment height. You also can't tell exactly what size matches a person based on height- leg length is the critical dimension, not height, and the two don't correlate exactly.

You want your legs to be almost extended when the pedal is down. But if your riding habits involve a lot of stopping and starting and waiting and stuff, you might like a lower position just for convenience. You'll notice a lot of guys cruising around on little bikes with their knees nearly hitting their chins. That's lousy for riding far or fast, but can be handy for mounting and jumping and looking cool and stuff.

If I stop for just a few seconds, I sit on the seat and put a foot down. Longer than that, I just stand up (platform pedals, no gymnastics required).

Lamplight 03-29-08 03:15 PM

I'm 5'9" and a 56cm bike fits me perfectly, so a 51cm for a person an inch taller than me seems quite small. I know they tend to size bikes smaller these days, but that's a pretty big difference!

bike_boy 03-29-08 03:23 PM

I guess the OP is longer in torso than legs ?

barba 03-29-08 03:25 PM

That actually sounds too small to me.

Platy 03-29-08 05:07 PM

Quote:

Originally Posted by Random Rider (Post 6427150)
When i am one my seat i can only touch the ground with both my toes.

Sounds normal for most bikes. Think about it. If your leg is fully extended at the bottom of the pedal stroke, to reach the ground while you're on the seat your leg will have to be a few inches beyond fully extended. Your basic options are

(1) (A stay on the seat option) Lean the bike when you stop and stand on one leg

(2) (Another stay on the seat option) Look for curbs and stones to put your foot on when you stop

(3) (Still another stay on the seat option) Use a so called crank forward bike. You pedal in sort of a half reclining position but when you stop you can put both feet straight down onto the ground

(4) (A come off the seat option) Dismount forward off the seat and stand over the top frame tube when you stop the bike. This is why people always recommend to select a bike with a couple inches of standover clearance. You can't always do it if you're short legged. Some bike frames give more standover clearance than others.

(5) (Another dismount option) Fully dismount at a stop.

I think the right frame size is whatever is comfortable for you. Most people can follow the usual fitting recommendations. Some can't. I think the people who can't follow the usual bike guidelines are already aware from previous life experience that they have out of the ordinary body geometries.

wahoonc 03-29-08 05:18 PM

Quote:

Originally Posted by Platy (Post 6427731)
Sounds normal for most bikes. Think about it. If your leg is fully extended at the bottom of the pedal stroke, to reach the ground while you're on the seat your leg will have to be a few inches beyond fully extended. Your basic options are

(1) (A stay on the seat option) Lean the bike when you stop and stand on one leg

(2) (Another stay on the seat option) Look for curbs and stones to put your foot on when you stop

(3) (Still another stay on the seat option) Use a so called crank forward bike. You pedal in sort of a half reclining position but when you stop you can put both feet straight down onto the ground

(4) (A come off the seat option) Dismount forward off the seat and stand over the top frame tube when you stop the bike. This is why people always recommend to select a bike with a couple inches of standover clearance. You can't always do it if you're short legged. Some bike frames give more standover clearance than others.

(5) (Another dismount option) Fully dismount at a stop.

I think the right frame size is whatever is comfortable for you. Most people can follow the usual fitting recommendations. Some can't. I think the people who can't follow the usual bike guidelines are already aware from previous life experience that they have out of the ordinary body geometries.

Good advice, but also take into consideration the geometry of the bike I have one with a very high bottom bracket and there is no way I can put a foot down from the saddle without falling over, but that is the exception rather than the rule.:p

Aaron:)

Platy 03-29-08 05:25 PM

Bikes have significantly different bottom bracket heights. As a short legged person I like bikes with low bottom brackets. However, the lower the bottom bracket the more likely a pedal will scrape the ground on an uneven surface --> increased accident potential.

barba 03-29-08 05:29 PM

It might be easier to answer the question if you post a picture of yourself on the bike.

BarracksSi 03-29-08 05:37 PM

Quote:

Originally Posted by barba (Post 6427825)
It might be easier to answer the question if you post a picture of yourself on the bike.

+1 -- it really depends on the style of bike. Some of them are set up so that you can stop flat-footed and still get proper leg extension at the pedals.

Also, normally, when I see 5'10" and 51 cm, I blurt out, "No way, that's wayyy too small."

Dahon.Steve 03-30-08 05:19 AM

I would like to see the seat post he's using to fit a bike that small.

CommuterRun 03-30-08 05:49 AM

A 51 cm for someone 5'10" Sounds small to me, too. But like was said, a lot depends on the geometry of the bike.

Stand flat footed straddling the top tube. For a road bike you should have about 2" clearance between the top tube and your crotch, about 4" for mountain bike. A little more for either is fine.

This measurement is not as important as overall fit.

The only style of bike that you should be easily able to reach the ground with both feet while in the saddle are some of the cruisers like those made by Electra, Rans, etc.

Random Rider 03-30-08 10:24 AM

When standing over the bar i def don't have 2 inches of clearance. But the bike guy said its a good fit and he would'nt have sold it to me if it was to big. I can try to post a pic. How should I pose? Standing flat footed over the bar? I never thought i had short leg but maybe that is the case.

BarracksSi 03-30-08 10:42 AM

Take a picture with you actually on the bike, preferably with your leg nearest the camera extended to the bottom of the pedal stroke.

You're saying that you have less than 2 inches of clearance from the top tube, right? What's your inseam, anyway? And are we sure that it's 51 cm and not 61?

Random Rider 03-30-08 11:16 AM

Sticker on bike says 20" 51cm. I'll try to take a pic later.

BarracksSi 03-30-08 11:21 AM

What kind of bike is it? Brand, model, etc?

Random Rider 03-30-08 02:24 PM

Trek 7100 Hybrid bike.

BarracksSi 03-30-08 02:50 PM

Quote:

Originally Posted by Random Rider (Post 6431986)
Trek 7100 Hybrid bike.

Aha, okay -- that makes a difference.

What I mean is, when people say "xx cm", they're usually talking about a road bike frame. I'm 6'2"-ish and have a 60 cm road bike with a slightly shorter stem, for example; somebody 5'10" would be best on a 56 cm-ish frame.

But, I have a mountain bike with a pretty similar geometry to your 7100 (sloping top tube, etc), and its size is... dang, the sticker's gone.. I think it's a 21" frame. BUT!... manufacturers measure their frames a little differently, too, so my Schwinn likely isn't a geometric cousin to your Trek.

So, your 20" bike is a size M on Trek's site -- http://www.trekbikes.com/us/en/bikes...0_series/7100/

Yours may too big for you. However, for me and my mountain bike, I can hardly reach the ground with both toes while seated... but I'm comfortable, and I can ride for a long time. I fit correctly on that bike. If I'm on a bike that's too small -- which I've done before -- my lower back starts killing me within fifteen minutes.

Trucker_JDub 03-30-08 03:03 PM

I'm very comfortable on my 58cm with me standing at 6'0"

BarracksSi 03-30-08 03:05 PM

Quote:

Originally Posted by Trucker_JDub (Post 6432159)
I'm very comfortable on my 58cm with me standing at 6'0"

Yeah -- but in this case, 20" doesn't necessarily "equal" 51 cm, either.


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