# Method to determine if top tube effective length is good fit.



## excr125rracer (Jun 10, 2010)

I read a thread somewhere on this site that contained a general rule of thumb to determine if a bikes effective top tube length is roughly correct. I have searched and cant find it again. It stated something about the length being correct if the handle bar hid the front axle from view. I am imagining things or just overlooking it. Any help here would be appreciated.
I have tried out a 18" Trek 3700 and 4300 both felt decent though their respective geometries were slightly different. I also rode both a 17" and 19" Specialized Hardrock Sport Disc, I could definitely tell a difference in them, the 17" felt better though the 19" didn't feel bad.
I have been riding motorcycles since 1985 and have about six years of amatuer motocross experience. I tend to get into my normal, bent elbows, head over the bars, racer's tuck and some of the bikes' axles are visible behind the bars, while some were hidden by the bars. I am used to sliding forward on a bike to weight the front end in turns and am not used to being more limited in my body positioning as on a bicycle.
I do realize that stems with different heights and or lengths, as well as flat or low rise bars will affect the body position. 
My mountain bike experience started (don't laugh) with a Murray Baja back in 1983 or 1984 when I was a kid. In 1992 I picked up a 20" or 21' Ross Mt. Rainier with street wheels on it while attending MMI in Orlando. My last mtb was a 19" 1999 Raleigh M80 that was used for fitness while i was still racing mx.
I am 5'9" with a 32" inseam with no shoes on and an average length torso, In dress shirts I wear a 32/33 sleeve.
I am getting back into bicycles now that my son and daughter have gotten old enough to ride themselves. I want to get something that will be good for bike paths now and later trails when the kiddos get older. Thanks in advance.


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## Straz85 (Mar 20, 2009)

Go to a good local bike shop, they will take all the necessary measurements and should help you out to make sure you get the correct size.

If you'd prefer to do it yourself, there is a bike size calculator on http://www.competitivecyclist.com/.


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## AndrwSwitch (Nov 8, 2007)

excr125rracer said:


> I read a thread somewhere on this site that contained a general rule of thumb to determine if a bikes effective top tube length is roughly correct. I have searched and cant find it again. It stated something about the length being correct if the handle bar hid the front axle from view. I am imagining things or just overlooking it. Any help here would be appreciated.


I've heard that rule myself, but applied to road bikes. I don't think any of those rules are very good though. If you imagine someone with a particularly long neck, they'd have to move their handle bars uncomfortable far forward to obscure the axle. It's more like a correlation.

I take fit calculators with quite a large grain of salt too, because I think they leave out a couple things that really effect fit - rider flexibility, weight and power output all have a big effect on what riding position someone will tend to have. I think people can drift as much as a full size, maybe even more, if they're making large changes in fitness level and body composition. My mountain bike in its current state feels a little long and a little low if I go for a cruise in my neighborhood, but I sometimes wish the handlebars were even further away and even further down when I'm racing. I've seen some very complicated fit calculators, but I think that the best fit calculator is how a bike feels to me. I guess a power meter might help if one really wanted to get crazy about it.

You still get a lot of freedom to move around on a mountain bike. It sounds like you're talking about sliding forward on the saddle on a motorcycle. Obviously that's a lot more limited on mountain bikes, but I think a well-fitting bike should allow the rider to get behind the saddle or stand up and climb a hill. There's some flexibility in bike fit - you can change stems and handlebars, saddles, seat posts, etc.

Was the Hardrock your favorite? I've been riding mine for four seasons and racing it for two, and while I've done a fair amount of shuffling of components, I'm quite happy with the result. Trek's offerings are quite solid too, and you've been on enough bikes that riding more probably won't improve your final decision. So get your favorite, and get after it.


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## excr125rracer (Jun 10, 2010)

*Recommendations on sizing from lbs.*

From my experiences so far with the different lbs, has been that I am not spending much or am looking at "low" end bikes, therefor all they seem to be worried about is standover height, not total fit on a bike. I am looking at this next bike purchase as a step to better and or multiple types of bikes for different types of riding in the future, think growing kids and my skills getting better. 
No offence to anyone on here, but I have seen quite a bit if elitist attitude from bicyclists, granted it not has been a majority but it has been close, unless you are looking at anything at or over the $1000.00 range. What gives, is this a common experience?
In the amatuer motocross world there is a small amount of that same attitude, but it goes away when you smoke them on the track or trail. Generally I am used to a very inclusive, family, we all have to stick together, type attitude. I am a friendly person and want anyone coming into the sports or hobbies I enjoy to have a good time and feel like they belong, thus they bring more people into those hobbies. This will strengthen these sports and hobbies.
Sorry for the rant.


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## bad mechanic (Jun 21, 2006)

For someone starting out, trust the bike shop to put you on the right size frame. Once you get some experience and are able to try out different bikes, you'll start to get a feel for what you prefer, and what your body feel comfortable with.


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## AndrwSwitch (Nov 8, 2007)

excr125rracer said:


> No offence to anyone on here, but I have seen quite a bit if elitist attitude from bicyclists, granted it not has been a majority but it has been close, unless you are looking at anything at or over the $1000.00 range. What gives, is this a common experience?


I've been riding bikes for a long time. The most welcoming groups of cyclists I've run into so far are cross country and cyclocross racers. The competition's out in the open, so it doesn't really matter who spent what on their bike. When everyone's claiming not to be competitive, and people have bike configurations that actually slow them down, though, it's another story. Competition becomes about how dedicated to the sport you are, as expressed by how much your gear cost, or how much less than retail you spent on it. I guess there's some correlation - it's expensive to get parts that don't wear out rapidly if you spend 10+ hours/week off-road with them. But if all people cared about was the riding experience, everyone would be on frankenbikes cobbled together from their first well-fitting frame, surviving parts, and Shimano or SRAM's workhorse component groups. Nobody would buy XTR rear derailleurs.  And bar ends might still be in.


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## trailville (Jul 24, 2006)

I tried that bike fit calculator from Competitive Cyclist a couple of years ago and it came pretty close to what I typically ride (I've been riding mtbs since the early 90s). As to the LBS, some are better than others (a lot better), so keep that in mind. If all they're doing is checking standover and giving you the old "how does that feel", that really doesn't cut it. That said, I don't think they need to be doing 20 measurements on you to get you a reasonable fit. If the guy knows what he's doing, he should be able to look at you on the bike and come pretty close, the rest is up to you. 

The good thing about mtbs is that you don't need a perfect fit. In fact, I don't know that anyone can calculate the perfect fit for you. Unlike a road bike, you move around a lot (changing body positions) on an mtb, and personal preference changes things. I find a lot of guys my size prefer a smaller frame size than i ride. I personally think a lot of these guys are riding too small a bike simply because when they were noobs, a smaller frame with an upright riding position felt nice to them so they went with it, and the guy that sold it to them took the easy route by not pushing them into a more appropriate size.


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## excr125rracer (Jun 10, 2010)

*Thank you*

Thank you to all for their input. I sse that some say to go with a small frame which makes the bike responsive, while others recommend a larger frame which forces you to put more weight onto the front. I still have good flexibilty and having to reach further forward to the bars wont bother me too much, but there are limits to that. A 2009 19" Gary Fisher Wahoo definitely feels to long, I think is is something like 24.4" effective top tube length. I now have something to work with.


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## mitzikatzi (Sep 9, 2008)

excr125rracer said:


> ..snip...
> No offence to anyone on here, but I have seen quite a bit if elitist attitude from bicyclists, granted it not has been a majority but it has been close, unless you are looking at anything at or over the $1000.00 range. What gives, is this a common experience?
> ...snip
> .


For what ever reason bikes and bike parts are expensive. A lot of people want the cheapest bike they can find. Really some very cheap bikes are really just BSO (bike shaped objects) . Some cheaper bikes are fine on bike paths etc.

I think somewhere between $500 and $1000 you start to get a Mountain bike (or Road) bike that can be used as it is designed for. So I think that is why there is that $1000 figure at that price you get a proper mountain bike that will survive many miles off road with little needed in the way of repairs. So maybe when you mention you are going to spend $1000 people know you are going to buy a good bike.


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## AndrwSwitch (Nov 8, 2007)

excr125rracer said:


> Thank you to all for their input. I sse that some say to go with a small frame which makes the bike responsive, while others recommend a larger frame which forces you to put more weight onto the front. I still have good flexibilty and having to reach further forward to the bars wont bother me too much, but there are limits to that. A 2009 19" Gary Fisher Wahoo definitely feels to long, I think is is something like 24.4" effective top tube length. I now have something to work with.


IMHO, the fit of the bike should be reflective of your riding position at the power output you use for most of the ride. The handlebars should be wherever it's comfortable for you to put your hands when you're in the position obligated by that level of effort. You shouldn't have much weight on your hands - if you do, you'll get pain in your hands, wrists, elbows, shoulders, back, neck, etc. Totally unpleasant, and there's really no performance gain you're getting to justify it. Even if you're riding sitting bolt upright, with your hands off the bars and at your sides, close to half your weight is on the front wheel. A bigger bike is totally unnecessary for that.

Remember, you're the engine. So part of the role of the frame is as an engine mount. One can get very complicated about it, like all the instructions and calculators online, but if you use yourself as the measuring stick it's a lot simpler - most of the time, whatever fit is most comfortable when you're riding at your usual level of effort is the right fit. Of course, it's nice to have a couple of options - that's why a lot of XC racers are using bar ends, unfashionable or not, and why road handlebars have three principle hand positions, and a couple more if you're creative.

I think for most people, there's a stem length that gives the best compromise between uphill and downhill handling. So the ultimate frame size would be one that put your contact points (bars, saddle, pedals) in the right places while using your preferred stem.

Hope I'm not re-complicating things too much.


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## trailville (Jul 24, 2006)

excr125rracer said:


> A 2009 19" Gary Fisher Wahoo definitely feels to long, I think is is something like 24.4" effective top tube length. I now have something to work with.


That's a rather long ETT for a 19" frame. Some Gary Fisher models run a rather unique geometry.
FYI, I'm about a half inch taller than you and my XC bikes range from 18" frames to 19.5" frames with ETTs generally in the 23.5" to 24" range. I typically run stems of 100mm to 120mm on those bikes (this is usually a little longer than the stock stems). This is also where preference comes in. Stem length changes the steering characteristics, so if you prefer long stems you don't want to go too long on the TT, and vice versa. Bar width also plays a role here.


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