BB drop effect for commuting/touring?
 

i'm in the market for a new (complete) bike to be used 80% of the time for commuting and long weekend rides w/ rear rack and pannier, and 20% for medium loaded touring w/ two panniers on the rear and a small front rack w/ rando style bag+supplies.

my riding tends to be comprised of 80-90% on pavement (including rough roads), and 10-20% on gravel/dirt/trails.

the two bikes i currently have my eye on are the (2016) Jamis Aurora Elite and Salsa Marrakesh.

besides the gearing, the quality of components look to be fairly similar on the two.
the one thing i'm noticing that differs greatly between the two is the 12mm in BB drop.

Aurora Elite = 65mm BB drop
Marrakesh = 77mm BB drop

i'm wondering what sort of advantage one would have over the other, and what sort of real world difference i could expect to feel on each bike. i've heard that the lower the bottom bracket the more stable the ride is, especially when loaded, but is that enough of a reason to choose a bike with a 77mm drop as opposed to 65mm?

You're talking a difference of one-half inch. I don't think it will be a big deal. Higher BB is less likely to pedal strike if you happen to pedal through a turn. Your saddle will also have to be 12mm higher above the ground to account for the higher BB. Lower BB will be more steady but a little more prone to pedal strike. Saddle can be slightly lower.

My Brompton has a pretty low BB , so Its an easy comfortable thing to stop and put a foot down.. perfectly suited for purpose ..

Drop is relative to the Wheel Radius , with a Tire on It , what are those Numbers ?

axis difference between centers of hub & BB but wheel size determines how close to the ground the BB is ..

So doing a 27" ->650b conversion also moves the BB down

and the Crank arm choice also lets the saddle height be lower with a Longer arm, & higher with a shorter.

Your question is oversimplified .. flip a coin.

FWIW: wheel/tires will be 700c x 35, crankset will be 170's

Unless you're racing CX or riding a FG, BB drop isn't going to have a big real world impact.

That is not like actually measuring the actual wheel radius.

The lower BB will put you lower on the same bike. That improves the handling (lower center of gravity) but increases the likelihood of banging or scraping a pedal.

That's one of the major differences between a cyclocross bike and a touring bike; the cyclocross bike has a higher BB for obstacle avoidance.

Low BB is good, unless it's too low. 77 mm drop sounds good.

That said, there are many other differences between the Aurora and the Marrakesh so I doubt I could pick out the difference in BB height. If it were the exact same bike otherwise, you'd probably notice the difference.

The Jamis has quicker geometry (BB height and shorter chainstays.) They both look like great choices (really dig those metal fenders on the Jamis) but the Salsa would be my choice as it has a kickstand plate.

In a word, no, BB drop is not enough of a reason to choose one bike over the other.

I ride an Aurora with a 65mm drop and a Rivendell Sam Hillborne with a 78mm drop. Yes, the lower bracket of the Sam feels closer to the ground or stable in that sense, but it's such a small factor in the overall ride experience. The Jamis is far easier to ride with no hands - if that's not a test of stability, I don't know what is. I prefer the Jamis for pavement and commuting (my commute is 9 miles pavement, 4 miles gravel bike trail, each way.) It 'feels' like I sit higher and a bit taller compared to cars. I'm 6',190lbs and I just feel more imposing out there. A bit more like I mean business and a bit less vulnerable. I dig the sport touring geometry as well, it can handle a load without being too pokey.

The Hillborne feels more at home on trails, dirt roads, or even urban settings w/ curbs and whatnot. I have it set-up with thicker tires, 38mm vs the 32mm on the Jamis - which actually measure closer to 28.

I think that the Sam feels a bit like a trail bike that I can ride on the pavement whereas the Jamis feels like a road bike I can ride on some light trails. The Sam is for fun and the Jamis is for speed but like I said, there are so many factors that contribute to the overall ride other than BB drop.

The Marakesh looks nice, I looked into Salsa myself at one point (the Vaya) .Don't quote me on this but I'd be wary about the the frame's compatibility with other racks and more importantly, fenders. For some reason I remember reading a review that pointed out the owner's frustration with the lack attachment points near the rear dropouts. Maybe it's been resolved since then.

In general I think bikes these days are too high in the BB. Even when I used toe clips, my bikes were much lower slung. My rando bike has a BB about 1" lower than my old road bike, and 2" lower than my MTB. I find it distinctly easier to start and stop with the lower BB. Once riding, not much difference.

I sometimes think of putting 27.5" wheels on my 29" just to lower the BB. Not seriously.

So, all things being equal...

I've done a lot of experimenting with different bikes and how geometry affects ride and I've come to consider BB height as more important than BB drop because tires have such a huge impact. For example, the 26" Surly LHT is a touring bike and has a "lower" BB or "higher" BB drop than most 26" bikes. However, Surly designed that bike for tires in the mid-30mm range so if you put 50mm tires on it, which many people do, it no longer has a low BB.

In your case, a 700c x 35mm tire has a diameter of about 700mm and a radius of 350mm.

BB height = Radius - BB drop

350 - 65 = BB height of 28.5cm. That's a pretty high BB

350 - 77 = BB height of 27.3cm. That's a pretty low BB and based on what I've read, it's pretty standard for old school road riders. If you expect to ride in rough terrain, 27.3 cm may be too low.

I think you would feel a considerable difference between the two bikes but which is better is a matter of personal preference. If at all possible, test ride each bike or if you can't find a Marrakesh to test ride, find a 700c Surly Long Haul Trucker. The LHT has about as low a BB as anything out there and is very similar in design theory to the Marrakesh.

I've thought of this as well and even went so far as to put 26" wheels with 55mm tires on my Karate Monkey as a proof of concept. There was nothing at all wrong with the resulting handling but it no longer rode like a Karate Monkey. It didn't even ride like a Troll, which was my hope. I think that much lower BB (compared to both 700c KM and a Troll) completely took away that nimble feeling that characterizes the KM & Troll. It basically turned my KM into a 26" touring bike.

thanks for your description of the Aurora vs Hillborne. even though the Marrakesh is different than the Hillborne, it still definitely helps in understanding some of the geometry differences in relation to ride feel etc.

i've been reading similar concerns about the rack compatibility of the Marrakesh. sounds like only Salsa's racks are compatible with that frame, and the rack that comes with it isn't rated very high for weight capacity. they have alternator plates that allows for fender mounting, but doesn't resolve the mounting issue for third party racks. a shame really as the rest of the bike seems more or less what i was looking for.

i would be a 52cm in a LHT which is only offered for 26" wheels, so unfortunately it wouldn't be a close comparison for me for a Marrakesh.

For me the main effect of having a lower bb is that places the handlebars relatively higher for the same size frame. This has a big effect on comfort.

You mean "lower BB drop" as in the numeric figure, right?

As opposed to the BB being closer to the ground.

Just for clarification, BB drop has no relationship whatsoever to wheel and tire size. It's the measure of the BB center distance below the line created by connecting the centers of the wheel hubs (dropouts). BB distance from the ground, OTOH, is a function of tire radius minus BB drop (as mentioned above).

For instance my old KHS 26" MTB had a higher BB than my 700C road bike. Its BB drop was very small in comparison to the road bike.

http://www.bikecad.ca/faqFiles/bb_drop.png

Yes to the first. The frame is measured from the center of the BB.

marakesh has the rear brake MTB style, so has a raised rack eyelet so needs a special rack with short legs.
Aurora has chainstay brake mounts, compatible with normal accessories.

I don't know if you're specifically referring to the Marrakesh but I have had two Vayas and it has always been very easy to attach racks -- front and rear -- and fenders. No interference with disc brakes and no problems whatsoever. My fenders are regular SKS, the front rack is a cheap no-name and the rear rack is a cheap Axiom. In fact, the ease of attaching things is a big benefit of the Vaya. Too bad if that has changed with the Marrakesh. I suggest asking Salsa, they are very responsive.

Re the kickstand plate, I was initially concerned about it's never an actual problem, there's always something to lean against and the bike is less likely to fall over than it would be on a kickstand.

The Marrakesh has the alternator plate which is what causes this whole problem in the first place. The rack mounts to the swing plate bolt which sits very high up, so the legs are shorter on the salsa specific racks. On top of that I believe they all do not come with the plate to allow fenders to be mounted, so you must buy this plate for another $60 (I know this to be true only on the fargo).

I really like the look and idea of the Marrakesh but I think the alternator plate is just screwing over salsa. I do not see this bike every being on par with a vaya for touring, commuting I think it will be just fine. It I do not think will have world presence like an LHT either.

There's a lot of good advice here. I agree that BB drop shouldn't be a major criterion for your decision. You'll get used to either bike. And they both look like fantastic bikes. I want to read ride reports from you!

I don't understand how we can discuss BB drop without considering crank arm length.


Jamis specifies three different crank arm lengths for the Aurora Elite, depending on frame size, which sounds like a good idea; but these different crank arms all come with the same BB drop. So the smaller framed Aurora Elites have more pedal clearance than the larger ones. Go figure!

Salsa doesn't specify the crank arm length of the Marrakesh. There's attention to detail for you!

Bottom line, BB drop and crank arm length only matter if you're getting near the extremes, and on these bikes you aren't, and it won't make much difference one way or another.

Well a taller person generally rides a larger frame size, and needs longer cranks. It all depends on the person and their ideal fit, though.

the crank arm lengths for the Salsa Marrakesh are listed at the bottom of the "build kit" tab: here

i'd be going for a 54cm in a Marrakesh, whereas i'd go for a 50cm in an Aurora Elite (standover of the 53cm is too high for me).

with all that said, i'm now also considering throwing one more option into the mix:

building up a 52cm New Albion Privateer, with gearing (48/36/26t + 11-32t) and components (brakes + shifters) similar to a Long Haul Trucker.

i like that the geo of the Privateer is pretty much right in between touring geo and CX geo, and similarly that the BB drop of the Privateer is kind of right in the middle of that range at 72mm.
i am aware that the tubing isn't as beefy on the Privateer, but i'm wondering if that would be an issue since i will only be using it for more med/fully loaded touring about 10% (would be using it with a rear rack and single pannier the rest of the time).

any opinions on that?