Wednesday, June 15, 2016

Off Road Drop Bars 101: The Importance Of Frame Design And Stems

"Drop bar" bike. Purposeful design to accommodate a drop bar here.
This time I am going to cover the final pieces of the puzzle when it comes to off road drop bars- the frame and stem. Many folks do not consider the design choices which are made to manufacture a "drop bar specific" design. It's a given that "road bikes", and "gravel bikes", for the most part anyway, are going to have drop bars and therefore you do not have to jump through any weird hoops to get these drop bars to work on these drop bar designed bikes. Obvious, right? Well, maybe too obvious. 

The issues arise for drop bar users for mountain biking, and to some degree gravel riding or other "non-traditional" uses for drop bars, because the frames maybe were not envisioned for use with a drop bar. This causes no end to confusion for those who want to try a drop bar out. The main focus of our attention regarding the understanding of this issue has to be on where we want our hands to be in space.

Imagine that you are on a flat bar mountain bike that fits you well. Your hands are on the grips, and the bar runs perpendicular to your wrists, for the most part. Now imagine that your hands stay in the same plane as before, but the bar runs in a line that is more parallel to the stem. You just "twist" your hands by moving the thumb clockwise a bit, but in the same plane, same height off the ground. This is where you want your drop bar's extensions to be when you finish mounting your drop bars. Well.....ideally, this is true. In practice, that may be difficult, and this is something I want to illustrate in this post.

My Singular Gryphon. Note the relationship between the saddle height and grip area, denoted by my shaky looking lines. 
In the case of a bicycle designed with drop bar use in mind from the get-go, like a Salsa Cycles Fargo, or like this Singular Gryphon shown above, the designer has made choices which will help put the drop bar in a place that makes sense from a riding feel and performance perspective that also does not require odd stem selections. "Normal" stems can be used, which opens up a lot more choices when it comes to dialing in a good fit and feel for many riders.

Note that I have a typical Bontrager stem with a modest amount of rise in a length that is a pretty common one- 100mm. I could easily find a stem with a shorter, higher rise, a shorter, lower rise, or even the opposite. Choices with which I could make the bike feel and ride just the way I want it to. Singular's Sam Alison did this by shortening the top tube's effective length, lengthening the head tube, and using other subtle geometry tweaks which, as a whole, make using a drop bar on this bike a very natural thing. But what if you have a bicycle which doesn't have these design cues?

Using a bicycle meant for a flat bar makes fitting a drop bar much more difficult and limiting.
Well, let's use my 2003 Campstove Green Karate Monkey as an example here. The first thing you might notice is that the head tube is shorter and the top tube is longer than on the Gryphon. This is critical in looking at fitting a drop bar to a bike like this. Drop bars add length to your cockpit and need height to get the drop section up to where your normal flat bar grip would be at. (Remember the third paragraph above?) This means you are probably going to be looking at a short reach, high rise stem to get where you need to be, or close to that, with a drop bar retrofit on a bike designed for a flat bar.

Note the lines I drew on the grip area and where the saddle height is on my Karate Monkey. Comparing that to the Gryphon, you can see how my saddle to handle bar/grip area drop is greater on the KM than it is one the Singular. This is using the shortest reach, highest rise stem I could find easily. There are other choices, but they are few, rare, and you'd better hope that they get you where you want to be in the end with the drop bars you have chosen. Velo Orange is supposed to be coming out with a better stem for this application, and when they do, I'll get that and this set up should be better then. In the end view, a custom stem is almost your best bet, and you'd better love the bike you want to convert to drops for off roading, because that custom stem will not be cheap.

The same bike with the same stem and a Gator Bar resulted in a too low extension position.
Let's come full circle now. This all started out with the Gator Bar review when I showed how that bar had too deep a drop, amongst other flaws. Sure, if you wanted to get a custom stem, you could alleviate that issue, but with other, better drop bar offerings, why would you spend that kind of money to get that bar? I just cannot justify that solution to make that handle bar work.

In review, a drop bar for off road use should feature sweep in the extensions to a degree, flare to the drop section, enough to clear the wrists and forearms, and then it really needs to have a shallow drop and a short reach. This allows riders to have an easier time of it when retrofitting a drop bar to a flat bar designed bike. Weird, oddly proportioned bars don't make that job easier and sometimes they make it impossible without resorting to rare stems or going custom. Finally, the radius of the drop bar's bend must not be such that it makes it difficult to make the hoods and the drop section usable. Bars like the Gator Bar and the Woodchipper are good examples of what not to design into a drop bar's radius.

Here are the links to this series:

5 comments:

phillip Cowan said...

Looks like time to resurrect the old LD stem. I think this could resolve a lot of the issues for people who are interested in building a rigid 29er as gravel bike(me). Lately I've been poring over geo charts looking for a frame with a workable top tube length. Going too small means you end up with frame that will have forty miles of seat post sticking out. I understand the concept of seat post as suspension, but at some point it starts to look ridiculous. Going too big is a deal breaker for drop bars. I'm a poor working schmuck so a custom frame is not an option. I'd even considered building an LD style stem with almost zero reach, maybe even dead straight. It would be an odd looking duck but this would get the height where you need it without making the reach excessive. The only drawback I see is it might make the handling a little weird due to lack of weight over the front wheel. I guess it's one of those things you have to try before you really know. I've built a couple of stems in the past but never an LD. We do have a pipe bender at work. Hmmm. What do you think? Is it worth the effort?

Guitar Ted said...

@phillip Cowan: You may want to check out this Velo Orange post from April: http://velo-orange.blogspot.com/2016/04/more-stem-stuff.html

It would appear that the LD type stem they show there is coming and should cost about $80.00. It has been tested to pass EN mtb standards, and will come in at least two colors, (black & silver), so that would be a good one to wait for.

On making your own: Well, it is a satisfying task and you may hit a home run for yourself, or you may be in trouble if you are not well versed in how to make a stem that can be ridden safely. I don't know you well enough to say one way or the other. That said, would buying an $80.00 stem that has passed a standardized test be worth less than one that you would make? How much time would that take you? Based on labor at $500.00/day, minimum, I would weigh my options carefully.

I'll be looking for the Velo Orange stem myself to try out.

phillip Cowan said...

I don't want to overstate the case. When I say I've built stems before I did all the machine work and them had one of my welder buddies TIG it together. My friend can weld up the crack of dawn. My welding on the other hand is highly suspect. The last stem we put together has many thousands of miles on it and hasn't killed me yet. As for the cost I always seem to have more time than money and the work was done in my spare time(the venerable G job)so didn't cost any thing. Still $80.00 is very reasonable and I wouldn't have to call in any favors from the welders.

Guitar Ted said...

@phillip Cowan: Thanks for the clarification. If you should decide to fabricate your own stem, by all means, have your friend weld it up! It sounds as though you have a good resource there. As I stated in the post, a custom stem is sometimes the best option, and with rigid 29"ers like yours, it may be the only reasonable option.

Adam said...

The alloy stem from the VO blog is sold in Europe as the Ergotec "Charisma" with a 20 degree rise, "High Charisma" with a 45 degree rise, and both angles available in 90mm and 110mm reach, and all combinations of rise/reach are available for 25.4mm and 31.8mm bars.

http://www.ergotec.de/produkte/vorbauten/sub/ahead-vorbau/produkt/high-charisma-31-8.html

I have one on a rigid mountain bike frame that's been converted to a drop-bar commuter; it's a nice little product. Highly recommended if you need a high-rise 1-1/8" stem and can get your hands on one. I'd love it if VO started importing them to the US.