Thursday, April 23, 2009

EBBs Vs. Sliders

The other day Colin "I think it is perfectly reasonable to wear a bucket for a helmet" Reuter forwarded me a question regarding EBBs (Eccentric Bottom Brackets) Vs. Slider style rear dropouts on single speeds.

Since the only people who really ponder such matters are Single Speeders (and really only the biggest dorks amongst that contingent) I'll give you a quick rundown on the types of tensioning systems used on Single Speeds. There are a couple other solutions out there, but I'm going to stick to the ones below for now.

Here you've got you Rear-Facing Horizontal. Fine for a fixed gear or a track bike, really lame for a Mountain Bike. Mountain Bikes have Disc Brakes, they just do. Hybrids and Children's bicycles have V-Brakes. This "solution" was used because tensioning the chain with varying gear ratios would cause the relationship between the Disc Rotor and Caliper to change. The easy way out was to run a V-Brake on the rear. Leaving the ass end of your bike firmly planted somewhere in the mid-nineties.

Simple Expander Style EBB, Common on most EBB mountain bikes. This is the type of EBB used on both of my Fisher Rigs and My Ferrous only a bit bulkier. The current Fishers use a model with cut-outs, reducing the weight significantly. I had PVD machine out the EBB on my '07 Rig to save some weight, but that's beside the point...

The Good:
Easy and quick adjustment allows you to swap out gears before rides or races. Rotor and caliper stay in absolute constant relationship. No potential for rear wheel slippage. Certain fit issues can be addressed with fore/aft position of EBB. Very unlikely to slip out of adjustment. Adjustment changes BB height.

The Bad:
Creaky. Must be pulled out and cleaned repeatedly to maintain quiet. Totally screws up your Saddle height and fore aft adjustment. If you are an XC racer-dork or Endurance type bloke, you will probably find having to adjust your fit every time you change out a gear pretty damn annoying. HEAVY. This is by far the most lard-assy system. Adjustment changes BB height.
I've heard people say they like to run their BB in the up or down position (you get the same tension on the chain in either one) depending on the terrain, i.e.; run it low for fast, buff stuff and run it high for "East Coast" technical, rocky stuff. I always keep mine as low as possible. In the "up" position I feel like I'm standing on a skateboard...on stilts. Keep the BB low, keep the center of gravity low, corner better, go faster.



Carver makes a nicer version using a more complex expander wedge system with a nylon sleeve which eliminates the creaking. A good upgrade for a Fisher Rig or any bike with the same BB shell diameter.

Niner Bikes was using a simple Set-Bolt Style EBB, now they have some crazy new deal. They claim it is the holy grail, I really know nothing about it other than that it exists and that it sounds pretty cool. This one is red.

Set Bolt or Pinch Bolt Style EBB. I don't have much experience running one of these but I have seen what happens to the EBB after many adjustments. The Bolts make little divots in the EBB. When you make an adjustment the bolt wants to slide back into that divot. Probably not the best system. I'd take an expander over one of these.

Now to The Sliders. Paragon makes the end all be all of Sliders. Kona has their own version as I'm sure other folks do as well. I used these on my Independent Fabrication Single Speed. I really had no problem with them at the time.

The Good:
Saddle height and fit are obviously not influenced by changes in gear ratio. The relationship between the caliper and the rotor stays constant. They are pretty light.

The Bad: Adjustment requires re-centering wheel. Changes wheel base. Gear changes most time consuming of any system.

Conclusion...er, really depends on your needs. If you change gears a lot and either don't mind monkeying with your fit or could care less about it, go EBB. If you want to save weight and if and when you do change out your gear you don't want to monkey with the fit, go Slider. If faced with the choice between Set-Bolt style EBB and Slider, go slider. Which I think is what I was actually supposed to address here.

Is that really a conclusion?

Big Bikes may have magically re-appeared at the top of the Google search listings (which I will not crow about, I learned my lesson Death-Bots...please don't hurt me Death-bots, have I told you how sexy you look today Death-Bots?) but it is still not a place people generally come for technical advice. Which, of course, won't stop me from speaking of such things in my own special way.

-t

5 comments:

Hill Junkie said...

Excellent review. I run an expander style EBB on my Dean Ti singlespeed. I would dearly love to run it in the "up" position, as my pedals seem like they run about 2" off the ground in the "down" position. Good for keeping CoG low, bad for clearing anything more than a pebble sticking up out of the trail. The bottom position is pretty much bottom dead center, very low. When I run up, it creaks profusly and works loose. So loose that I can get chain drops (very bad on SS). It never works loose, it actually seems to make the chain too tight, when run in down position. Don't understand all the dynamics, seems like just the opposite would happen. I haven't touched the EBB for over a year in bottom position and all is good.

PVD said...

I found out about this really cool invention. It's called a "Shimano 810 Saint Rear Derailure" It seems to solve all of the problem that you mention. It is also so advanced that it allows the use of up to 10 gear choices at the rear of the bike. You should check it out. Pretty cool!

Colin R said...

Aw dammit... PVD beat me to the joke :(

James said...

Funny, It doesn't happen often but when I see someone walking with there bike and there derailure dangling from being smashed on a rock I secretly laugh to myself. I feel bad for them and tell them tough luck as I roll by. Or when they pick the wrong gear to make it up a short hill and wind up crashing in front of me I think that's too bad.
My point is, if people want to run one gear let them do it and give them the respect they deserve. I respect the geared riders, especially when they are beating me.

Tim said...

I vote for the Bushnell EBB.
TImmyD