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Old 11-04-06, 12:19 PM   #1
hoss10
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Sloping top tube

To recap Im having my dream touring bike built and I just received the preliminary drawings.

I have very unique body measurements in that I have a 31 inch in seam and Im 6'5" tall (O.K. Im a freak), because of this we decided to use a sloping toptube to give me some stand over clearance. Besides looks, the bike looks like a Mountain bike, (a really cool mountain bike) is there any disadvantage in having a sloping toptube? Why do more road/touring bike not use them it seems like a good idea when it comes to stand over.
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Old 11-04-06, 12:31 PM   #2
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Quote:
Originally Posted by hoss10
To recap Im having my dream touring bike built and I just received the preliminary drawings.

I have very unique body measurements in that I have a 31 inch in seam and Im 6'5" tall (O.K. Im a freak), because of this we decided to use a sloping toptube to give me some stand over clearance. Besides looks, the bike looks like a Mountain bike, (a really cool mountain bike) is there any disadvantage in having a sloping toptube? Why do more road/touring bike not use them it seems like a good idea when it comes to stand over.
No there is nothing wrong with sloping top tubes. You end up with a bike that has a smaller, lighter, stiffer frame. That's the reason that you see so many mountain bikes with them. If there is a downside it would be in a stiffer rear triangle which would make for a slightly harsher ride.

The reason you don't see them in touring bikes (and I'm donning my asbestos undies as we speak ) is because we touring nuts tend to a rather conservative bunch. If anyone still made Draisines, a not insiginficant part of the touring population would argue that they are all that you need to go around the world. Chains are just too complicated for real touring use
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Old 11-04-06, 12:40 PM   #3
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Originally Posted by hoss10
Besides looks, the bike looks like a Mountain bike, (a really cool mountain bike) is there any disadvantage in having a sloping toptube?
None that have been revealed or exposed.
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Old 11-04-06, 01:29 PM   #4
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My measurements (33" inseam at 6'3") put me in the nearly the same boat as you, Hoss10. I'd say the sloping top tube is the best way to go -- probably only way -- that you can get a bike that you can stand over without wrecking your wedding tackle, yet still have a cockpit length and saddle-to-handlevbar relationship that makes sense for you. Sadly, however, I can't afford a custom frame, so I'm stuck with buying the tallest bike I can barely standover and then just adjust the heck out of the saddle setback, stem, etc.,

FWIW... Soma is building some very cool framesets with sloping top tubes (Smoothie, Smooth ES and Doublecross, for example), but none have long enough chainstays for me. My feet are so big/long (size 14) that I need a long stay to keep my heel from striking the derailer, much less pannier. Not that I suggest you buy something other than the custom you're planning to buy. It's just I like the looks and attitude of the Somas. I'm hoping that Soma will finally start selling a true touring frameset to compete with the Surly Long Haul Trucker. The Somas are the same price, but made of better stuff and lighter.
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Old 11-04-06, 01:38 PM   #5
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Originally Posted by cyccommute
No there is nothing wrong with sloping top tubes. You end up with a bike that has a smaller, lighter, stiffer frame.
Depending upon the amount of slope and the size of the frame, what you save in frame weight and flex you may pay for in the form of a longer, heavier seat post.

Sloping top tubes are great for fitting people with short legs and long torsos, and they are great for reducing the amount of inventory bike shops need to carry because they can sell fewer sizes.

For people with longer legs and shorter torsos, a horizontal top tube means we can save the added weight and flex of a really long seat post.
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Old 11-04-06, 11:47 PM   #6
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I have them on both my touring bikes - one 700c and the other 26 inch - when you have a loaded rig they can be a little squirrly depending on the weight distribution and I find a sloping top tube just plain easier to get your feet on the ground. I find this comforting in wet weather, in traffic, or coming a hill and needing to stop.
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Old 11-05-06, 09:50 AM   #7
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Hoss10, I have sloping top tube bikes, because I also have long torso, short legs... but as you know, the compact frame geometry bikes have short chainstays, which lead to pannier "heel strike" problems. These can be gotten around with the proper rear rack. The Jandd Expedition rack gives me adequate clearance.
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Old 11-05-06, 11:20 AM   #8
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Hey Hoss, glad to hear your bike is coming along. Sounds like you've got a good solution there with the slanted top tube. If you recall I have your issue in terms of sizing. When we measured it out, the frame manufacturers couldn't believe the dimensions. They wound up spec'ing a bike that was about 52cm. They wanted to the bike shop to take another measurement. We wound up with a bike that was 56.5cm. At that height, the top tube is a tad bit high for me, but not a, um, deal breaker. Keep us up to date on the bike, can't wait to see pictures.
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Old 11-05-06, 03:24 PM   #9
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Thanks for the information guys. Sort of what i figured. No problems with the top tube it just looks a little odd. (that's O.K. so do I). No worries about heel strike (even with my size 13 hooves) it's been designed with over a 18 inch chainstay! The joys of custom designs.
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Old 11-05-06, 03:40 PM   #10
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Who's the builder? You really should give them a little free press here, hoss10. Most custom frame builders aren't very good really-- they often build one bike they happen to think this the greatest frame on earth and then knock it off a little different for each *new* customer. Honestly-- most buyers would be better off with an off the self stock Trek.

But you are getting a bike with a sloping top tube AND 18 inch chainstays!?! Now that's a custom bike! And a frame builder with a lot of vision. You're going to love your new bike.
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Old 11-05-06, 03:45 PM   #11
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Originally Posted by tacomee
Who's the builder? You really should give them a little free press here, hoss10. Most custom frame builders aren't very good really-- they often build one bike they happen to think this the greatest frame on earth and then knock it off a little different for each *new* customer. Honestly-- most buyers would be better off with an off the self stock Trek.

But you are getting a bike with a sloping top tube AND 18 inch chainstays!?! Now that's a custom bike! And a frame builder with a lot of vision. You're going to love your new bike.
Yeah, please tell. Maybe he'll give us a two for one sale!
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Old 11-05-06, 04:50 PM   #12
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Originally Posted by tacomee
Who's the builder? You really should give them a little free press here, hoss10. Most custom frame builders aren't very good really-- they often build one bike they happen to think this the greatest frame on earth and then knock it off a little different for each *new* customer. Honestly-- most buyers would be better off with an off the self stock Trek.

But you are getting a bike with a sloping top tube AND 18 inch chainstays!?! Now that's a custom bike! And a frame builder with a lot of vision. You're going to love your new bike.
Agreed. And coincidentally, I have just written something along the lines of your profile of many framebuilders for my website! Great minds think alike...
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Old 11-05-06, 05:30 PM   #13
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It's a True North frame, built by Hugh Black. Hugh is a Mechanical Engineer who builds bikes. So far it has been a great experience, as I said in a past post Hugh spent a long time measuring me and watching me ride. He then sent a design for me look at and provide input. The tubes are large diameter top (oval) and down tubes to handle my weight. The bike will not be pretty in a classical sense, but it will be a blast for short legged old fat guy to ride.

PS Did I mention that Hugh's welds are almost perfect.
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Old 11-05-06, 08:18 PM   #14
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Mine and my wife's bikes have sloping top tubes.
Two disadvantages I've found-
1. They hang funny on our hitch rack. This is no big deal, but if you have a twin arm rack, make sure it'll fit.
2. This one was unforseen, and kinda POs me- Polar bottles wont fit in the seatpost cage- the top tube is too close to the downtube. A standard 24 oz bottle will fit, but a 24 oz polar is too tall.
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Old 11-05-06, 11:05 PM   #15
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Quote:
Originally Posted by halfspeed
Depending upon the amount of slope and the size of the frame, what you save in frame weight and flex you may pay for in the form of a longer, heavier seat post.

Sloping top tubes are great for fitting people with short legs and long torsos, and they are great for reducing the amount of inventory bike shops need to carry because they can sell fewer sizes.

For people with longer legs and shorter torsos, a horizontal top tube means we can save the added weight and flex of a really long seat post.
If you use a seatpost of the same diameter as can be found on most road bikes, I'd agree. I've even used those in the past on old steel mountain bikes. But my current mountain bikes all have 12 to 14" of seatpost exposed and they aren't flexy. But they are 31.0mm diameter posts, too.
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Old 11-05-06, 11:29 PM   #16
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Originally Posted by cyccommute
If you use a seatpost of the same diameter as can be found on most road bikes, I'd agree. I've even used those in the past on old steel mountain bikes. But my current mountain bikes all have 12 to 14" of seatpost exposed and they aren't flexy. But they are 31.0mm diameter posts, too.
So, basically, you've taken away some lightweight butted seat tube reinforced with a crossing member and replaced it with an extra heavy, straight guage piece of tubing that needs all that mass to make up for the fact that it isn't supported with a cross member and this is "better" how? For the same weight and stiffness, you can build a traditional geometry frame with stiffer tubing and a shorter seat post.

Bottom line, a sloping top tube only provides benefit in terms of fit for =some= riders and inventory reduction for the bike business. All this nonsense about "lighter and stiffer" is pretty much unwarranted marketing claims. Don't confuse the characteristics of a =frame= with those of a =bike=.
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Old 11-06-06, 12:18 AM   #17
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Quote:
Originally Posted by hoss10
It's a True North frame, built by Hugh Black. Hugh is a Mechanical Engineer who builds bikes. So far it has been a great experience, as I said in a past post Hugh spent a long time measuring me and watching me ride. He then sent a design for me look at and provide input. The tubes are large diameter top (oval) and down tubes to handle my weight. The bike will not be pretty in a classical sense, but it will be a blast for short legged old fat guy to ride.

PS Did I mention that Hugh's welds are almost perfect.
Hey Hoss10...I just sent you a private message about you frame
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Old 11-06-06, 04:14 AM   #18
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Originally Posted by kf5nd
Hoss10, I have sloping top tube bikes, because I also have long torso, short legs... but as you know, the compact frame geometry bikes have short chainstays, which lead to pannier "heel strike" problems. These can be gotten around with the proper rear rack. The Jandd Expedition rack gives me adequate clearance.
A trailer also avoids the heelstrike issue very nicely and fixes a lot of the "percieved weight" issues of a loaded touring bike.
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Old 11-06-06, 09:28 AM   #19
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Originally Posted by halfspeed
So, basically, you've taken away some lightweight butted seat tube reinforced with a crossing member and replaced it with an extra heavy, straight guage piece of tubing that needs all that mass to make up for the fact that it isn't supported with a cross member and this is "better" how? For the same weight and stiffness, you can build a traditional geometry frame with stiffer tubing and a shorter seat post.

Bottom line, a sloping top tube only provides benefit in terms of fit for =some= riders and inventory reduction for the bike business. All this nonsense about "lighter and stiffer" is pretty much unwarranted marketing claims. Don't confuse the characteristics of a =frame= with those of a =bike=.
No because the seatpost isn't that heavy. It's not like the post is a solid piece of aluminum rod 350mm to 400mm long. One of my mountain bikes has the stock Specialized seatpost and the other has a RaceFace. Neither is that heavy. I've had heavier seatposts that were much shorter on other bikes. The Raceface post is 240g for a 400mm post vs a Ritchey road post that is 250mm long and weighs 250g. You can certainly find lighter posts for a road bike but I have the Ritchey post on my touring bike.

The reason I have so much post showing is because both of these bikes are mountain bikes for which you need much more clearance than a traditional framed bike. I've had older mountain bikes with smaller diameter posts (27.2mm vs 32.0 mm) with less post exposed and I have bent them. But with a larger diameter post flex has never been a problems...and this is on mountain bikes that are ridden much harder than road bikes.
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Old 11-06-06, 06:13 PM   #20
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Originally Posted by cyccommute
No because the seatpost isn't that heavy.
Neither are a few centimeters of frame tubing. Since metal frame tubing is usually butted and seatposts usually are not, a cm of extra seatpost tends to be heavier than a cm of extra frame tubing. So while you =might= save more frame tubing than you add seat post, the seat post you add is heavier. When you account for this, the net difference in weight and stiffness going from a sloping to horizontal top tube is trivial to none.

If there were a true advantage in weight and stiffness of a sloping top tube, then in a sport where these minor differences are actually relevant it would be a bit hard to explain how that sport's top event had been won seven of the last eight times without it. (It could even be eight for eight, I haven't kept up on the controversy.)
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Old 11-06-06, 10:35 PM   #21
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If there were a true advantage in weight and stiffness of a sloping top tube, then in a sport where these minor differences are actually relevant it would be a bit hard to explain how that sport's top event had been won seven of the last eight times without it. (It could even be eight for eight, I haven't kept up on the controversy.)
Which mountain bike event is that?
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