I've always thought the bottom bracket on my Singular Swift should be in the lower EBB position when the chain is tensioned, like so:
However, a bike-swap for a lap round the local woods and a subsequent comment from my mate about having never experienced pedal strike round that trail on his bike has got me thinking.
I went back to the same trail yesterday and set the EBB round the other way, so the BB was higher by maybe 10mm. Much more confidence pedalling through the rocky and rooty bits.
Have I been working on the wrong assumption for nearly a year, or is the higher BB going to upset me when the riding goes more vertical and I should go back to the lower height?
Lots of EBB-equiped bikes on here; how have you lot got yours set?
Got mine set at about 2 O'clock when viewed from the drive side, logic being that if it were to slip it would be clockwise (direction of pedal stroke) and the chain would tighten and not loosen. Obviously it's higher up too, so pedal clearance is better but I can't say I've really found this a problem.
Out of interest, when you set you EBB to the top, did you also raise your saddle 10mm?
yep I tend to run mine higher in preference to lower & I don't usually bother moving my saddle as the difference is so small if I try & keep the EBB in the top half of the circle. In fact, I find there's more difference in seated height between different pairs of padded shorts! I'm not much of a technical riding expert though so probably wouldn't notice any benefits or otherwise of EBB position in that regard.
On my old GT peace I always set the EBB at about 2 o'clock so it could roll forward to account for chain stretch, or slipped like Ian suggested! If it was going to slip, I always thought it would go when stood on the pedals and groin cross bar collisions are too painful
I've not had any slippage issues at all; very happy with the EBB solution, especially coming from a slot-dropout On One (I don't think I ever did an entire ride without the rear disc rubbing, even with 2 chaintugs).
I have the Swift setup as per the second, higher BB photo for lunch today. Sounds like I was the odd one out before, so it'll be staying like that for the weekends ride too.
I don't think it is relevent to slippage which ever way you have it. By really honking on the pedals the chain under tension is effectively trying to pull the BB axle back towards the rear wheel axle; it's not the rotation of the cranks that is trying to rotate the ebb.
I guess I'm in the minority that prefers mine in the lower position. I like the slightly lower centre of gravity and lower saddle height which helps me to feel in the bike rather than on it which is particularly noticable on the 29er.
Never really thought about this before, I always set the EBB on my Swift to the lower half.
The reasoning behind this was to give the BB maximum clearance when in XC mode.
There are a couple of large steps on the Chase where I've bent a chainring, but this was on my other bike (a 26er) theoretically I have more clearance now and not bent owt .... Yet
Now off to the man cave to change it round for tomorrow to try out in the up half.
Can it really make that much difference?
Mart wrote:Never really thought about this before...Can it really make that much difference?
My thoughts exactly, and I never even considered it until my mate mentioned the pedal strike after the test ride.
Having done 4 muddy hours on the Swift in the higher BB height position today I reckon it does help with pedal strike, and I haven't noticed any difference on the vertical bits (I still minced down them! )
I'll be interested in your comments after trying it as the Swift has a much bigger EBB, and hence difference in BB height, than the Pegasus that a couple of the guys above have.
btw, my Pegasus is a custom jobbie & amongst other things I specified a full link EBB a la Swift, which I prefer to the half link faffage of my original Pegasus.
Reporting back after my trial today. The upshot is pretty inconclusive
Tried the ebb in the upper half has made little difference to the way the bike feels when ridden.
I didnt feel any advantage over having higher pedals avoiding pedal strike
And I didn't feel any real difference with lower centre of gravity less ground clearance.
Going to run it in the high position for a bit longer just in case it takes a bit longer.
I would just suit yourself
Mart
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