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Frame size...inseam...confused

Old 02-21-06, 01:46 PM
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huskerpat
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Frame size...inseam...confused

I bought my first bike since I was in junior high last night. Got a Trek 7.2 FX. the confusing bit for me is the frame size. I think I got the right size, but I am 5 10" or so and have a 29" inseam. the bike I bought has a 17.5" frame since I could stand flat footed and not hurt "the boys". I tried a 20" frame and I had to stand on my toes. Does 17.5" sound about right considering my inseam?

I tried seaching but didn't find quite the info I was looking for.

Thanks
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Old 02-21-06, 02:34 PM
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That size sounds right for you. I have a 7.5 FX with a 22.5 inch frame. I'm 6 feet with a 34 inch inseam and have about 2 inches clearance. You'd want more clearance for a mountain bike.
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Old 02-21-06, 03:29 PM
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When you say 29" inseam, are you referring to the inseam of your pants, or the inseam of your legs? I'm 5'8", and my inseam is 32.5"...

Might wanna check this thread for more discussion...
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Old 02-21-06, 03:38 PM
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Now, don't confuse frame size with standover height.
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Old 02-21-06, 04:19 PM
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Don't confuse a bike with pants. Inseam doesn't have a lot to do with it as long as you can clear the frame while standing over it. Top tube length is more important.
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Old 02-21-06, 04:55 PM
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Originally Posted by huskerpat
I bought my first bike since I was in junior high last night. Got a Trek 7.2 FX. the confusing bit for me is the frame size. I think I got the right size, but I am 5 10" or so and have a 29" inseam. the bike I bought has a 17.5" frame since I could stand flat footed and not hurt "the boys". I tried a 20" frame and I had to stand on my toes. Does 17.5" sound about right considering my inseam?

I tried seaching but didn't find quite the info I was looking for.

Thanks

Were you trying to apply the "inseam minus 9" " rule of thumb discussed in the Breaking Away thread? If you were, that rule of thumb does not work on MTB's, cross bikes, most hybrids or any other bike with a high bottom bracket. It only applies to roadbikes and even then not all road bikes are measured the same these days. It is just a starting point.
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Old 02-21-06, 05:27 PM
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Originally Posted by Ranger
Don't confuse a bike with pants. Inseam doesn't have a lot to do with it as long as you can clear the frame while standing over it. Top tube length is more important.
I couldn't stand clear of the top tube on the 20" bike. It was rather uncomfortable and I'd have to dismount when stopped. It sounds like I bought the correct size. Now it just needs to warm up enough so I can get outside on it. Thanks all.
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Old 02-21-06, 06:42 PM
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Originally Posted by huskerpat
I couldn't stand clear of the top tube on the 20" bike. It was rather uncomfortable and I'd have to dismount when stopped. It sounds like I bought the correct size. Now it just needs to warm up enough so I can get outside on it. Thanks all.
That's what's confusing me. Is this a mountain bike, or a road bike? I ride a 23" road frame, and I'm 5'8". Pants inseam is 30", leg inseam is 32.5", standover height is 32".
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Old 02-21-06, 08:07 PM
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Although the height of the top tube is of some importance so you don't mash up the bottom bits, the most important size parameter is the distance to the bars when seated and with the seat correctly positioned fore-aft. Too close and you will feel like you're pushing away from the bars all the time with your arms. Too far and you get sore arms/neck/shoulders from over-reaching. 5'10" sounds a bit large for 17.5" frame, although MTBs have smaller frames...
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Old 02-21-06, 10:03 PM
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Originally Posted by Blue Order
That's what's confusing me. Is this a mountain bike, or a road bike? I ride a 23" road frame, and I'm 5'8". Pants inseam is 30", leg inseam is 32.5", standover height is 32".
The Trek FX series is considered a hybrid road bike and or fitness bike, depending on if you look online or in their catalog. Looking at the frame specifications, the offset and wheelbase are different from the 7200 hybrid frame.

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Old 02-21-06, 10:21 PM
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Be careful there...My Talus is a 17" frame, and by mtn bike standards, it's actually a bit big for me, and I run a 30" inseam. Pretty much if I dismount abruptly, I can end up hurting the boys...it's clearance is acceptable for road bikes, let's put it that way.


....That's what happens when you think a 17" is a 17". I should have bought a 16".
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Old 02-22-06, 09:45 AM
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Your right leg should be straight when the pedal is at the bottom.
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Old 02-22-06, 10:28 AM
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Originally Posted by flags6262
Your right leg should be straight when the pedal is at the bottom.
The guy at the LBS said that I should have a slight bend in my knee with the pedal at the botton. of course, that's just a matter of a seat adjustment.
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Old 02-22-06, 01:54 PM
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There was an old rule of thumb about having 1" clearance above the top tube when you stood over the bike but that was for classic road bikes with a flat top tube. The FX has a sloping top tube so you could have more clearance and the bike still "fit" you. You need to have enough top tube length so that your knees aren't hitting the handlebars or you feel cramped. You don't want the bike to be too large or you are stretched out and putting too much weight on your hands and shoulders, plus you won't have as much power if you are too far forward.

The FX series is meant to have the rider in a more upright position, similar to a mtb. If the frame is a tad too small you can get a longer stem, move the saddle back.

There should be a bit of bend in the knee when the pedal is at the bottom; if not you'll end up pointing your toes downward or rocking in the saddle. This will cause discomfort and possibly medical problems.

It's best if the bike fitter at the shop gets you fitted to your bike.
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Old 02-22-06, 04:05 PM
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Originally Posted by flags6262
Your right leg should be straight when the pedal is at the bottom.
No, there should be a slight bend at the knee.
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Old 02-24-06, 08:55 AM
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Have someone hold the bike or lean against a wall with your hand but keep the bike vertical and your right leg (without shoes) should be straight when the pedal is in the down most position. This is the proper fit. Also be sure you have 2 to 3" clearance over the top bar when you stand with feet (and shoes on) flat on the floor.

This is how 95% of bike shops size a bike for the correct fit.
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Old 02-24-06, 11:53 AM
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Originally Posted by jur
Although the height of the top tube is of some importance so you don't mash up the bottom bits, the most important size parameter is the distance to the bars when seated and with the seat correctly positioned fore-aft. Too close and you will feel like you're pushing away from the bars all the time with your arms. Too far and you get sore arms/neck/shoulders from over-reaching. 5'10" sounds a bit large for 17.5" frame, although MTBs have smaller frames...
I agree with jur.

While I wouldn't ignore standover height completely, it only matters when you stand over your bike. That's not a very significant portion of your on-the-bike time.

Seat tube height, which is the 17.5" frame size, doesn't matter much either. Seat height is the easiest adjustment that you can make on a bike.

Top tube length, which determines the distance of your handlebars to your seat is the biggie. that affects your comfort every minute that you're riding your bike. You can make minor length changes by replacing your stem, but that can get expensive.

Fortunately, bikes with longer seat tube sizes tend to have porportionately longer top tubes so, if you have average body porportions, when you get one right the other generally falls into line. The next time that you buy a bike you should have a better idea of what top tube length you're looking for.
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Old 02-24-06, 03:04 PM
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Inseam could be used in general for a Trek 7.* FX series due to the design. A lot of bikes can be judged this way. But as mentioned, mtbs and a lot of other bikes aren't shaped the way bikes were years ago so this rule is ever changing. Trying a bike is still a best bet. Some manufacturers have special calculations to adjust to help you find proper fit. A sloping top tube with 1-2 inches of crotch clearance could make for a massive bike :-)
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Old 02-24-06, 03:25 PM
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Originally Posted by flags6262
Your right leg should be straight when the pedal is at the bottom.

For a beginning seat height, your leg should be straight with your heal on the pedal at the farthest point. The farthest point is generaly when the crank arm is inline with the seat tube. This method will allow knee bend when pedaling with the balls of your feet on the pedals. Personnal adjustments can then be made to each riders preference.

Mountain bikers usually have their seat adjusted lower, but , this is subject to personnal preference and comfort per inividual.
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Old 02-24-06, 06:06 PM
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Originally Posted by flags6262
Have someone hold the bike or lean against a wall with your hand but keep the bike vertical and your right leg (without shoes) should be straight when the pedal is in the down most position. This is the proper fit. Also be sure you have 2 to 3" clearance over the top bar when you stand with feet (and shoes on) flat on the floor.

This is how 95% of bike shops size a bike for the correct fit.
Whatever. Not doubting that's how they do it. Just whatever.
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Old 10-03-14, 07:40 PM
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Hello how are you. My height is 5`&" and my inseam is 32". I buy one mountain bike is 18" frame size. Do you think that size bike is good for me?
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Old 10-03-14, 07:56 PM
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Originally Posted by bobbyl1966 View Post
Hello how are you. My height is 5`&" and my inseam is 32". I buy one mountain bike is 18" frame size. Do you think that size bike is good for me?
You do realize that your posting in a thread that has been dormant since 2/24/2006 (and half of the participants are no longer active)?

You might want to check out one of the newer forums here- Fitting Your Bike
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Old 10-03-14, 08:08 PM
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I not realize that i am almost new in that site. thank you for you tell me for that fit forum
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