Sloping Top Tube Madness
September 10th, 2006 by Guitar TedThe trend in hardtail 29″er design has been to drop the top tube/ seat tube junction to achieve a lower standover height. I have seen a few different solutions to this design, but the results have been less than desirable.
The one solution that really gets my goat is the “super sloping” top tube design, exemplified by the Inbred 29″er, Raleigh’s XXIX, and other similarly designed steel hardtails. Now, don’t get me wrong, I like standover as much as the next guy. Let my recent experience in acquiring a Raleigh XXIX be an example of what I am talking about.
The way I like to size a mountain bike is by top tube length. I’ve been on alot of mountain bikes and a few 29″ers now, so I know that a 23 and a half inch long top tube, (or there abouts) is just peachy for my riding style. When I pick out a production bike, I turn to the geometry page in the catalog and look right at the effective top tube length column. When I see my preferred top tube length, I pull the trigger. In the case of the XXIX, that meant I went with the medium frame size, which on the surface of things, might sound smallish for my 6′1″ frame. (no pun intended)
The thing is, the XXIX I chose got the “medium” tag because of it’s “super sloping” top tube, which makes the seat tube on this bike only 16″ long! Okay, let’s see here: a sixteen inch frame with a 23.4″ top tube? Not a usual length for a seat tube with that long a top tube. Out of curiousity, I had my 5′4″ wife stand over it and she could, in her bare feet! How much stand over do we need? I think it’s gone too far!
The frame will fit fine for me, but the supplied Easton seat post, at 350mm, will barely get the saddle up higher than the handle bars at max height. I had to order a 410mm seat post, which will get me right with the leg extension. This shouldn’t be. The seat tube on a frame with this top tube length should be a minimum of 18″ and a seat post that allows you to get the saddle higher than the handle bars without going to max height should be provided. ( It’s easier to cut off what you do not need than it is to add material!)
The question of why the bikes are getting designed this way is a fair one. First of all, I think alot of this is driven by the fashion of the day. Secondly: I think the manufacturers do this to get smaller folks on board 29″ers. They can tell their dealers, “It’s not just for big people. Look how low you can get the saddle!” What ever the reason is that this is being done, it’s goofy, and should be stopped. We don’t need copious amounts of standover. Heck, when I crash, I’m usually airbourne! Alot of good stand over does me then!
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If you run across any 23.75-24″ inch top tubes, I would love to help you in your testing process. I am just saying (xcbiker27@gmail.com) if that happens.
I am somewhat puzzled.
Our 18in frame has an 18in seat tube, and a 23.7in top tube.
It is a straight tube, welded from the head tube to the seat tube, with the tube centre dropped about 3in from the top of the seat tube.
It requires around 4in of seat post engaging in the frame.
The bikes come with 400mm posts - 350mm in the UK is more a roadie length for compact frames.
Your phrase “We don’t need copious amounts of standover.” does make me wonder what you’re doing out there.
So to sum up, you’d like to see the inbred 18in 29er with a longer seat tube?
I would like a 18″ On-One if possible. I will send out my address if you need a “tester”!
Brant: Lovely top tube measurement- don’t change it! The seat tube/ top tube junction is as you say. In the bicycle world, we measure things quite oddly at times. It might prove to be more usefull if we were to talk “center to center” with our measurements which would make the 18″ Inbred a 15.25″ frame. A little bit more revealing, I’d say. By your own admission, the seatpost needs to be inserted to at least the junction of the top tube and seat tube, so at least a “center to top” measurement would be better than calling it an 18″ frame. So then, let’s call it a 16″ frame, shall we?
At any rate, the seat post has to be inserted that far for safety reasons and I need 11″ sticking out above the seat collar, so yeah……410mm post has to be ordered. No big…..I love the way it rides, but I really do not need the top tube that low, and I don’t think it would have hurt to have welded the top tube up an inch or so higher on the seat tube. Hey! Then you could legitimately call it an 18″ frame! Beautiful!
The reason for me to spec my custom with a very low seattube is that my seatpost will be fully extended so it can flex. I’m riding a almost fully extended Moots ti 380mm seatpost in my RIG now and really like the comfort. When people have ridden my bike they often feel if my reartire isn’t too soft.
Hubert: No doubt that your titanium Moots seat post takes the edge out of the trail, but what do you think about seated climbing? Is your seat post robbing you of power by flexing when you mash the pedals? Perhaps it’s not a concern if you routinely climb out of the saddle.
Flexy seatpost? Is that the only disadvantage? I don’t understand your problem, other than looks. Clearly the manufacturers are trying to make a size range that fits a wide range of riders. I’m not sure I understand why that’s bad, since you only mentioned “budget” frames. Expecially since a year ago everyone was whining about too little standover on 29ers. It sounds like were damning them if the do at this point.
-M
Wolfy: I’m not here to “damn” 29″er manufacturers. I just don’t think that a 16″ frame with a 23.75″ top tube sounds like it makes any sense. Does it to you?
If this is what it takes to “fit a wide range of riders” then doesn’t it make sense to accomodate the larger, longer legged rider? As I stated, it’s easier to cut some seatpost off than it is to add some material. At least it wouldn’t cost me much more on the original purchase if 400mm seat posts were provided at the onset. I’m just asking that this all make some sense.
Again, the XXIX I have cannot even get the saddle three inches above the handle bar without the post being at max height, and that’s with the stem flipped! I tell you, It’s madness.
At 6′1″ I wonder if you’re longer than average legs and preferance in top tube length is not part of the problem. I would guess the average person at that height would fit the next size up better. It’s gotta be tough to design a production frame for every possible body proportion, and yes… standover is pretty high on my priority list.
two words
toeclip overlap
head tubes are where headtubes are. unless you want to design a “rigid only” 29er.
Okay guys, a little clearing up here. Standover is good “where you need it”, meaning where one would straddle the frame, right? We don’t need to continue to slope the top tube at such a severe angle that we end up with a really short seat tube.
Am I missing something here? Why is it that the seat tube “needs” to be so short?
Frankly, I don’t need the standover really. I used to ride a 20″ Kona 26er and standover was fine. However, I love the look of the long , dropped tt on my MOnocog. I think it look great. I have a 330×26.8 post extended 9 inches and I love the flex it gives me too.
I’m 6′4 and just ordered a Raleigh large.I thought it was a 20 but it seems to measure out at 18.5?I tried to ask the shop and Raleigh directly since they also have a x-large listed in their specs.Both say a large should fit.Well will it?I’ve ridden a Gunnar 20.5,Surly KM large and a Voodoo 21.Any ideas if I will like the Raleigh?It just seems like it’s going to be to small.I wish the people selling and making the bike could help out a bit more with the fit.
warren: It’s going to depend on what you have previuosly run for a top tube. The Large has a 24.4″ ( I believe that’s correct, I do not have my spec sheet handy) top tube. That’s “effective” top tube, by the way. You get that by measuring horizontally and level to the ground from the center line of the head tube at the top of the head tube, to the center line of the seat post. This takes into account the sloping top tube.
You are probably going to find that the seat post doesn’t extend far enough up to accomodate your legs. If your inseam measurement is 35″ or longer, you will definitely be looking for a longer seat post.
I got the medium, as I have stated, and the inseam measurement for me is 33.5″. I’m about two inches shy of making my legs extend the way I like. Therefore, I had to order a longer seat post. My seat tube is 16.5″ stock, out of the box. But since the XXIX has an eccentric bottom bracket, you can “cheat” a little bit for more seat tube length. Tension the chain with the BB in the lowest part of the shell and you can effectively gain a half an inch length on the seat tube measurement. This might make a difference in getting a new seat post or not. Worth a try, but I doubt it’ll work with your size on a Large.
Raleigh is supposedly going to make this available in an XL, which might be more to your liking. You’ll have to have your dealer inquire with their Raleigh rep.
Warren’s dillema illustrates the need for the collective LBS to start stocking more (if they have any) 29ers. It sounds like there wasn’t something he could try out before he ordered it. Bummer. It seems like many of us have gone out on a limb and made a best guess as to the size we need. I always look at every single number, but really should everyone have to? There’s nothing like actually sizing/fitting a bike personally.
GT - if he drops the BB into the lowest setting in the Eccentric will that leave less obstacle clearance? - Sorry for the somewhat dumb question, I’ve never touched an EBB so I’m not sure if there’s a way the ground clearance stays close to the same no matter where it’s positioned.
bdee: Yeah, rotating the EBB to the lowest position is going to affect clearance by the same amount you gain on the seat tube length. In my case with the XXIX, that is a half of an inch. That’s also going to affect stability, ( more stable with a lower BB) and also you can affect the knee over pedal set up by going to the forward or rearward posistion.
3rd try @posting a comment…
I like sloping TT’s, because i’m vertically challenged…:) [a shortarse by any other name would be the same...:)]
I also love my flexy Moots Ti seatpost that soaks up all sorts of vibes..really nicely.
However, I could live without any clearance between the TT and my ‘nads if I had to. After all, that’s what I have been doing most of my cycling life.
I agree that frame sizes should be TT height specific. XXL frames should have very high TT’s and small frames low TT’s.
What’s so hard about that?
The designer / builder just has to do his R & D properly.
R.
Oh yeah, and whilst i’m at it…NO cable guides on top of the TT, thank you.
Also, why sit down to climb? Is there anything more uncomfortable than sitting on the very nose of the saddle, hunched over the bars to keep the front wheel down while you spin madly away like a gerbil on speed in a treadmill whilst trying to negotiate the rocks, roots and bumps on a climb?????
It’s ridiculous !
Stand up and crank it like a man, forget the gears, select the middle ring and the appropriate rear cog and mash that mutha up the hill !
Damn it Ted, what are you, a frilly bloused big girl?
R.
Rainman: Ha! You make me laugh you goofy Aussie! It’s too bad we are so far apart because I think we’d get on quite well together. Frilly blouses or no.
I hear you on the climbing style. When I ride the single speed, ( all my 29″ers are single speed so far, by the way) off road on really steep stuff I do exactly as you say: Stand and mash! But I only get out of the saddle on last resort, because my motor doesn’t like it too well if I do alot of that. Actually, my days of XC racing on a fully taught me “The Posistion”, ( hovering above the nose of the saddle, negotiating all the rocks and roots) so I’m familiar and comfortable riding that way. It may be rediculus, but it works for me better, more often than not.
And then there is the whole gravel grinding thing, where out of the saddle climbing is almost never necessary. Just grinding out the gear, ala Ullrich style, on the single speed. That’s where your seatpost had better be stiff. Long gradual climbs. And don’t say it’s just a weird Iowa thing, because I’ve been on Rocky Mountain service roads and singletrack that mimic the same type of climbing, only miles longer!
Ahh……to each his own, I guess.
And could somebody pass the top tube clearance memo on to the cyclo-cross guys. They don’t seem to get it either. Thanks!
Hey-A quick and slightly unrelated question. On the Raleigh XXIX do you have to remove the crankarm(s) to move the EBB. With the Giga-pipe crankarms it seems I would have to remove them to tighten the chain and I’m hoping that’s not the case. Also bdee is right. I was able to actually try my XXIX out first at the shop. Makes buying the bike a lot easier when you can ride it first. Thanks!
jffmark, you do not have to remove the crankarms to adjust the EBB. It’s quite easy actually.
1. Loosen the two fixing bolts on the bottom of the BB shell
2. Rotate the cranks until you get a loose spot in the chain
3. Once you have the loose spot, you should be able to grab the crank BB and rotate the the whole EBB to your desired sweet spot
Good luck
Heheheh.. I’m sure we would get on fine Ted …… even though you are an American..lol..
Seriously, you tall ugly guys have the same sort of problems we short handsome guys have but on opposite ends of the scale..we are looking for more SO, you are looking for less….. s’rather funny.
Anyways, lets hope the 2007 bikes are better for us all.
R.
jffmark: One additional thing on the EBB adjustment. You will see two holes in the EBB itself on the driveside. They are there to fit a pin spanner, much like an old style, serviceable BB would have had. You can also take a Phillips head screw driver and insert it into one of the holes. You then use the crank arm to push on the inserted screw driver, which in turn drives the EBB around in the bottom bracket shell. This makes adjusting the chain tension really easy, plus you can hold the chain tension while you re-tighten the EBB pinch bolts.
You would have a mighty hard time turning the EBB any other way.
BACK TO TT VS STAND OVER. YOU NEED TO READ ALL THE SPECS BEFORE YOU BUY NOT JUST TT. IF IT WON’T WORK FOR YOU DON’T BUY IT. CONSIDER A CUSTOM BIKE WITH REAL CUSTOMIZATIONS.
THERE IS SO MUCH MORE TO SIZING A BIKE THAN THOSE TWO MEASUREMENTS.
BUCKY: Nice, but top tube measurement is not a measurement that you should compromise in bike fit. Also, “normally” a bike with a top tube measurement of 23.5″ or above doesn’t have a 16″ or less seat tube. You see? It doesn’t have a thing to do with a “standover” measurement, which is a nebulous measurement, at best. It’s about what you as a bike company spec for the ability to size people properly. In the case of the XXIX, the seat post is too short, or Raleigh could re-design the bike with a more appropriately sized seat tube for the top tube spec.
I have a spec sheet on the XXIX that was sent to me in June that does not list standover , just so you know.
I think what BUCKY meant was things like seat tube angle which has a serious affect on the overall cockpit length. By the time you’ve raised your seat to be three inches over the bars you’ve changed that measurement a lot. You’re also prone to catapult yourself otb, like you said before “when i crash i usually become airbourne”.
It sounds like you’ve made a habbit of buying more than one entry level bike sight unseen without human consultation. Let’s say you buy a km, an on one, and an XXVIX something or other. What’s that add up to, maybe $1500 if they were framesets? In the end you’ve shuffled a lot of parts around and attempted to adapt to three different beginner setups. You spent a bunch of imaginary cash online and overseas to a place where it’s okay to pay nine year olds pennies a day and spill their filth into the air and water. Clearly none of the bikes suited you and you’re still in the hunt for a new bike.
Unless you live way out in the sticks it’s not real hard to find a shop that carries custom bicycles that would be right for you from the start. You can pay somebody a fair price to fit you for a custom american made bicycle if you need custom in the first place. You’re likely to love and cherish that bicycle for a long time and spend that time riding it instead of complaining about how crappy your cheap bike is on the internet.
harold: Wow! Sorry that’s what it sounds like to you, but you couldn’t be more wrong. I understand and agree about the custom bike thing. One day, I will have one done up for me.
Too many assumptions on your part have led to erroneous conclusions. My cockpit length is a number which I have honed in on over eighteen years of riding off road. It’s a number that is the same on all of my bikes meant for off roading. Prone to catapulting myself over the bars? I’ve done it once since going to 29″ers in ‘03, and that was due to getting my front tire stuck in a sand pit, not by having my posistion screwed up, as you have implied.
Your crass assumptions about the manufacturers of my bicycles bears no resemblence to reality and is unworthy of further comment.
And by the way, I do not live “way out in the sticks” and I work at a professional bicycle dealer. Love and cherish a mere bicycle? I love and cherish something far more worthy. Finally, I don’t think my bicycles are “crappy”. I’m discussing a design feature that I think is a bit misguided and being handled poorly.
Hopefully this discussion can stay on target here and not devolve into silly assumptions and off topic rantings.
Thanks to those that have commented, I’ve enjoyed the discussion.
OT: ekoostick, did you ever play SubSpace?
back OT: at 6′2″, I am thoroughly tickled that my XL Astrix Monk - with quoted 33″ standover and 25.4″ TT - fits me perfectly. Felt like I was taking a gamble ordering it sight unseen, but it’s amazing. Looks like a real bike, too, not some dramatically-sloping weirdness.
for what it’s worth.
This whole thing sounds pretty simple to me. You shouldn’t have bought a Raleigh and should have done looked at all of the frame measurements before “pulling the trigger” Raleigh buily a bike to fit a range of people. If you don’t fit that range, look elsewhere. I am 6′2″. Their are bikes that fit me and bikes that don’t. I ride what fits me. Simple. Next time, aim before you pull the trigger.
This whole thing sounds pretty simple to me. You shouldn’t have bought a Raleigh and what you should have done looked at all of the frame measurements before “pulling the trigger” Raleigh buily a bike to fit a range of people. If you don’t fit that range, look elsewhere. I am 6′2″. Their are bikes that fit me and bikes that don’t. I ride what fits me. Simple. Next time, aim before you pull the trigger.
This whole thing sounds pretty simple to me. You shouldn’t have bought a Raleigh and what you should have done ws looked at all of the frame measurements before “pulling the trigger” Raleigh built a bike to fit a range of people. If you don’t fit that range, look elsewhere. I am 6′2″. There are bikes that fit me and bikes that don’t. I ride what fits me. Simple. Next time, aim before you pull the trigger.
oderus: Nice triple post there!
Anyway, if you would have carefully read through the comments, you would have seen where I did indeed look at all the frame measurements before “pulling the trigger”. Also, you would have read that my main beef is with the spec on the seatpost, if the design is going to be that way. Subsequently to this posting, Raleigh made a change to 400mm seat posts for their ‘08 XXIX and XXIX+G.
As far as being “simple”, well it’s anything but, as is usual in the real world. I doubt that I’m the only feller out there with this sort of beef, and I’m sure there are others out there like you too. Cool! To your point: the size range that Raleigh could fit would have been wider had they allowed for a 400mm post, right? Well, it would appear that at least they agreed with me, since, as you have read, they changed the spec.
Cheers! Have a graet summer!
Just came across this thread tonight, so I’m a bit late to the party. Anyway, I have a medium Raleigh xxix. I am 5 feet 9 inches tall on a good day (with bike shoes on). The stem is a 110mm Deda. And, yes, I had to get a longer post also. To get proper leg extension, the stock post was about 4mm above the minimum insertion line. Ted is 100% right in his assessment of the Raleigh needing a longer post. Personally, I like the aesthetics of the sloping top tube and I like the standover height. There ARE times when your wheels are sitting higher than where you’re going to put your foot down and the extra standover height is a real nadsaver.