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Old 11-26-07, 12:36 PM   #1
hhabca
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is 1" standover clearance important?

I was given an old frame which I'm thinking of building up into a commuter/touring bike. It's an older Bianchi, Asian made frame I suspect, manganese steel frame, 26.4 seat post - ie. nothing too special but it has braze ons for cables and DT shifters, and front and rear racks, and a RD hanger, so definately not a bottom end frame. BUT, it's a tall bike with a 62cm seat tube but a pretty short 56 cm top tube. That TT length is exactly what I normally ride, and with a 100mm stem I get my perfect bar-to-seatpost distance and a very comfy bar height 1" below the seat height.

I think it was originally a 27" wheeled bike, but with 700c wheels and 25mm tires standover is a tad under 34", so I can just clear it with regular shoes on but with my heals lifted a bit.

So the question is - does it matter that I don't have 1" of crotch clearance? Is there a safety reason I'm not thinking of for having more room there? Injury in a crash?


BTW: I've always figured the racer's 'rule' of getting the smallest frame possible (which puts me huntched over on top of a 56) is more for getting a short wheelbase, lighter frame and plenty of top tube clearance for thrashing about in sprints.

Last edited by hhabca; 12-07-07 at 08:45 AM. Reason: corrected some measurements - tt is a 56, seat post is a 26.4
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Old 11-26-07, 12:40 PM   #2
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No I have short legs and if I buy a bike with sufficient standover the top tube is always too short. Fit while riding is the most important issue.
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Old 11-26-07, 12:42 PM   #3
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On a road bike, room for the "boys" is less important. As was said, if it fits well while riding, you should be fine. Even then, I'd usually avoid a bike with negative standover clearance.
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Old 11-26-07, 01:07 PM   #4
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Top tube is really what matters for riding performance. I am not even sure why bikes are measured by down tubes. My most comfortable ride touches my "boys"with the top tube.
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Old 11-26-07, 01:31 PM   #5
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Ok, I'll put the parts on and see how it goes. It's only because of the 58cm TT that I'd even consider this frame. If it rides OK I might even repaint it (it's got some rust issues).
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Old 11-26-07, 01:32 PM   #6
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I have almost no clearance on my road bike and it hasn't been a problem. my big problem has been the seat type/position. but I think I've got that right now.
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Old 11-26-07, 02:03 PM   #7
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I think it depends where you're commuting.

MTBs are designed to have more clearance than road bikes, with the basic idea that one will most surely require more 'surprise' dismounts while riding off road. This makes a lot of sense, for men and women alike.

When I commuted in a quiet suburb, I often rode bikes that were larger. Some were tall enough to require that I stand on my toes to clear the top tube.

Now that I ride in stop & go city trafic, I always ride a mtb or undersized road bike. My commute is short enough where 'rider comfort' is not an issue. I deal with the short top tube and get a longer stem if need be. Even without 'surprise' or panic stops (and they happen all the time here) it's a pain to stop several times during your ride on a too-big bike. just my 2 cents.
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Old 11-26-07, 02:34 PM   #8
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I have no top-tube clearance on my 'beater. One can't generalize completely, but with old-school road bikes with a flat top tube, a bike with 1" of clearance and the seat at the appropriate height woud require a *really* long stem to be rideable.

As far as stopping, I don't get the problem. It's not like anyone's straddling the top tube at a light, right? You just tip over and put a foot down.
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Old 11-26-07, 06:33 PM   #9
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I put on shorts and running shoes - I can stand flat footed with the TT lightly making contact - I can still lift the front wheel about an inch without undue stress. I'd probably have trouble with 27" wheels and big tires.

I redid the measurements - this is a weird bike! 63 cm ctc seat tube, 56.5cm ctc TT, 87.5cm standover and a 1020mm wheelbase! Now I'm wondering if the front fork is bent because that WB seems so short, but with that 56.5cm TT maybe it's OK? I might get a picture of it up - in the 'saved from the trash' thread over in the CV forum.

Last edited by hhabca; 11-26-07 at 07:25 PM.
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Old 11-27-07, 09:11 AM   #10
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I have no top-tube clearance on my 'beater. One can't generalize completely, but with old-school road bikes with a flat top tube, a bike with 1" of clearance and the seat at the appropriate height woud require a *really* long stem to be rideable.


Yep - i either use a really long stem or better still I use the short stem and raise it, with a slightly upright torso - better in traffic. Again, I am only riding 6 miles each way, and most of that under 12 mph, so I don't need to be all aero.

As far as stopping, I don't get the problem. It's not like anyone's straddling the top tube at a light, right? You just tip over and put a foot down.
Theoretically your are right, but when you are stopping a LOT (like every other block or so), it becomes more of a drag to tilt - this is worse the larger the bike actually is. In real world applications, I find just rolling up to a light around here involves frequent 'panic stops' - not real panic, but people constantly do stupid stuff, step off curbs right in front of you, etc. Pedestrians cross against red lights all the time too. So you must be ready to hop off at any time. Even while coasting at a a few mph this can land you on a top tube and kinda ruin your day! Of course, as I said, this was different in more rural settings where I could ride for several miles without putting a foot down.....ymmv but i still say your route and riding conditions will affect your safety and equipment needs. When the boys (or girls, for that matter!) are involved, I always say better safe than sorry!
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Old 11-27-07, 09:30 AM   #11
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Theoretically your are right, but when you are stopping a LOT (like every other block or so), it becomes more of a drag to tilt - this is worse the larger the bike actually is. In real world applications, I find just rolling up to a light around here involves frequent 'panic stops' - not real panic, but people constantly do stupid stuff, step off curbs right in front of you, etc. Pedestrians cross against red lights all the time too. So you must be ready to hop off at any time. Even while coasting at a a few mph this can land you on a top tube and kinda ruin your day! Of course, as I said, this was different in more rural settings where I could ride for several miles without putting a foot down.....ymmv but i still say your route and riding conditions will affect your safety and equipment needs. When the boys (or girls, for that matter!) are involved, I always say better safe than sorry!
That's a good point. Then I would say, if you're facing that sort of maximum stupidity, I'd ride something more like a mountain bike with slicks. Smaller frame, more agile. I might throw a longer stem on it for comfort, and get the seat up to the point where you're not going to hurt your knees.

Compact-frame road bikes help with this too, because the top tube slopes down toward the crotch region. That way, you get a frame that fits as well as some, shall we say, breathing room.
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Old 11-27-07, 09:37 AM   #12
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I say build it up & ride it. I find the top tube distance is the most critical. Most of my bikes are 53, 53.5 & 54 cm seat tube CtC with Top tubes of 54-55 CtC. The smallest, a Bianchi, measures 51 X 55. Last Spring, I restored a vintage Zeus that measured 56 X 56. I barely cleared the top tube but was surprised I could adjust it to ride with out discomfort, I just had to be careful when stopping/starting. I eventually gave it to my son who usually rides a 59 cm. He found it a bit small but made it fit with a taller seatpost & loves the ride. Don
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Old 11-27-07, 12:05 PM   #13
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Quote:
Originally Posted by hhabca View Post
I was given an old frame which I'm thinking of building up into a commuter/touring bike. It's an older Bianchi, Asian made frame I suspect, manganese steel frame, 26.8 seat post - ie. nothing too special but it has braze ons for cables and DT shifters, and front and rear racks, and a RD hanger, so definately not a bottom end frame. BUT, it's a tall bike with a 62cm seat tube but a pretty short 58 cm top tube. That TT length is exactly what I normally ride, and with a 100mm stem I get my perfect bar-to-seatpost distance and a very comfy bar height 1" below the seat height.

I think it was originally a 27" wheeled bike, but with 700c wheels and 25mm tires standover is a tad under 34", so I can just clear it with regular shoes on but with my heals lifted a bit.

So the question is - does it matter that I don't have 1" of crotch clearance? Is there a safety reason I'm not thinking of for having more room there? Injury in a crash?


BTW: I've always figured the racer's 'rule' of getting the smallest frame possible (which puts me huntched over on top of a 56) is more for getting a short wheelbase, lighter frame and plenty of top tube clearance for thrashing about in sprints.
to a certain extent, nope. I have a bike that my LBS told me was too big for me. I can stand over it but not with a 1'' gap... its the most comfortable bike that I have owned... (its a trek 1220 that I bought used...).

It reminds me of when I was a kid. I road a dept store bike which tended to be a bit big for me...
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