Fifty Plus (50+) - Oversized Bottom Brackets

There is a trend, especially with CF racing frames, towards new BB standards like BB30, BB90, and BBright. This limits ones ability to swap parts around. For instance, having invested in a Quarq power meter that fits the threaded BB of my steel Gunnar, I find that my desire to be able to move the Quarq to a racing frame is limiting my N+1 choices. Of the bikes I'm currently considering, only one (Specialized Tarmac) is available with a threaded BB. There is a similar trend towards tapered head tubes. Both trends are based on eliminating flex, or at least making that flex elimination easier to accomplish.

So my question, to those of you who have experienced both the old and the new technologies, is: How much difference does it make?

Especially given I'm a big, 200 pound (well, actually 199.3 pounds now!) guy, should I bite the bullet and go with an oversized BB, reconfiguring my Quarq, or, (ga$p), buying another one?

I like my Tarmac. I believe it is race worthy and I would buy it all over again.;)

194714

I like my Tarmac. I believe it is race worthy and I would buy it all over again.;)

And I take yours has a threaded BB, Jet? Tarmacs come in a variety of flavors, many of which use an Oversized BB.

There are adapters available for your existing Hollowtech or GXP crank.

I'm looking, and finding a lot of adapters, but so far nothing that is GXP <> BB90 (Trek Madone)

Ahhh..., I would contact Trek.

I like my Tarmac. I believe it is race worthy and I would buy it all over again.;)

194714
^^^^ Great looking bike!:thumb:^^^^^

And I take yours has a threaded BB, Jet? Tarmacs come in a variety of flavors, many of which use an Oversized BB.

It's an external threaded BB.

^^^^ Great looking bike!:thumb:^^^^^

thanks... makes me want to say "I'm Batman":D

Man, I gotta learn the lingo. I thought Oversized Bottom Brackets was going to be a tribute to Queen's "Fat-Bottomed Girls."

thanks... makes me want to say "I'm Batman":D

Is that the bike that now has the PT?

Is that the bike that now has the PT?

The PT is in the hub of my training wheels that I can also use on my Roubaix and TT bike while training and in C races. Those 58cm tubular wheels are my Sunday-go-to-meeting wheels.

Wot's a PT?

PT = Power Tap hub power meter

I guess your saying you do not have an external threaded BB.
Isn't a Quarq pm mounted in spider of crank?

I have a 2011 Trek Madone w/BB90. I had my SRAM RED Compact Crank (BCD 110) from my old bike (which used a GXP external BB) re-installed to the Madone using required a BB90 BB kit. I chose the Enduro one with hybrid ceramic bearings.

PT = Power Tap hub power meter
thanks.

So this connects to a cyclocomputer, and replaces the old magnet on the spoke kind of thing?

thanks.

So this connects to a cyclocomputer, and replaces the old magnet on the spoke kind of thing?

It is a sophisticated cycle computer that measures power generated by the rider in watts. The hub has strain gauges and other internal bits that measures torque, speed, distance, watts, time and estimates cadence and sends the info wireless onto the CPU. I purchased the cadence sensor to get real cadence. Instead of training by heart rate I train using established power zones that are similar to heart rate zones but are more accurate because power generated is consistent where HR can vary due to heat, fatigue and other factors. I had to do specific testing to determine the lactate threshold heart rate and average watts produced over a specific time frame to generate the data needed to establish the power training zones. It reads complicated, and to me it is, which is why I invest in a coach and spend my time riding and following directions.:D

On the one hand, I gotta confess these oversized bottom brackets look pretty badass on a lot of new bikes...the sheer size of some of them conveys a solidity/rigidity that, in theory at least, suggests some sort of perfomance benefit.

On the other hand, the puny normal-sized bottom bracket on my TIG-welded steel Strong frame is so freakin' solid I can't imagine anything else being perceptibly more rigid, or offering any perceptible performance gains.

I know, "Failures Of Imagination Are Not Insights Into Necessity", yadda-yadda-yadda.

I understand where you are coming from Bob. In my case, with the wide and stiff bottom on my Tarmac I have never jumped on the pedals up a hill or sprint and had the chain rub the derailleur. Every effort seems to go into the wheels. My 1999 stiff aluminum Cannondale would rub quite heavily and my early-70's 531 steel Super Course would need constant trimming. If anything, it just feels good to have the bike respond to every effort the moment it’s made.

^^^^ Great looking bike!:thumb:^^^^^

I'll second that!
Very nice

I guess your saying you do not have an external threaded BB.
Isn't a Quarq pm mounted in spider of crank?

I have an external threaded BB on the current bike, but might not on the new one. And yes, the Quarq unit is mounted in the spider.


I have a 2011 Trek Madone w/BB90. I had my SRAM RED Compact Crank (BCD 110) from my old bike (which used a GXP external BB) re-installed to the Madone using required a BB90 BB kit. I chose the Enduro one with hybrid ceramic bearings.

This is good to hear, as it is exactly what I'm considering. I have a SRAM RED S975 (S975=Quarq) GXP standard crank on my bike, and one of the bikes I'm considering is the Madone. I had heard of the Enduro adapters, as Cervelo also references them (for their BBright BB). I just haven't been able to find the right one online. I'm trying to make sure there are no surprises when I pull the N+1 trigger, and want to be knowledgeable before I even start talking to the LBS. I'm currently considering the Madone, the Tarmac, and Cervelo Rx, and I'm fortunate that we have an LBS carrying all three, and that LBS has a relationship (spelled d-i-s-c-o-u-n-t) with my coach.

It reads complicated, and to me it is, which is why I invest in a coach and spend my time riding and following directions.:D

Me too. I'm trying to get my mind around the science and data, because that's just the kind of guy I am, but it truly is overwhelming. I've been gradually reading "Training and Racing with a Power Meter", which is the bible on the subject, digesting it slowly like a time-release protein powder. I'll finally be doing my threshold test a few weeks from now, when there is a break in my racing schedule.

I'm glad I don't race, just ride!

I'm glad I don't race, just ride!

To quote a great old commercial: "Try it; you'll like it."

Seems [Afaik], BB30 moved the frame width out to re internalize the External bearing stuff.

external stuff was compelled by Shimano, etc, jumping on the patent expiration
of Bullseye, tube attached to the right crank arm design.

the original design used needle and ball bearings , to fit in a normal 1.37" threaded shell..

To quote a great old commercial: "Try it; you'll like it."

I don't know, whether it's running, swimming, or bicycling, I've never enjoyed racing. I guess because I'm not usually good enough to win, but I'm competitive enough not to be satisfied with a "personal best."

Power meters are a bit on the pricey side for somebody who doesn't race. If you do, then ya gotta have one. If somebody offered me one for free, I wouldn't turn my nose up at it. :D

The price to get power-meter-geeky may be dropping significantly in the future. There are new pedal based systems, shoe based systems, pod based systems... and at least two consumer electronics companies getting involved.

I don't know, whether it's running, swimming, or bicycling, I've never enjoyed racing. I guess because I'm not usually good enough to win, but I'm competitive enough not to be satisfied with a "personal best."

I'm finding that, so far, I'm okay with "acquitting myself well". As I start entering age group events, we'll see if I can maintain that attitude. One thing is for sure - there are some hella-fast people out there.

This is good to hear, as it is exactly what I'm considering. I have a SRAM RED S975 (S975=Quarq) GXP standard crank on my bike, and one of the bikes I'm considering is the Madone. I had heard of the Enduro adapters, as Cervelo also references them (for their BBright BB). I just haven't been able to find the right one online. I'm trying to make sure there are no surprises when I pull the N+1 trigger, and want to be knowledgeable before I even start talking to the LBS. I'm currently considering the Madone, the Tarmac, and Cervelo Rx, and I'm fortunate that we have an LBS carrying all three, and that LBS has a relationship (spelled d-i-s-c-o-u-n-t) with my coach.

As far as we know, Trek hasn't made a BB30 frame yet, only ones with BB90. They are not the same thing. BB30 frames need cranks with a 30mm spindle. BB90 frames still use cranks with 24mm spindles, such as the SRAM S975 GXP one that you have. You don't need an adapter, you just need to make sure your frame comes with SRAM bearings and not Shimano bearings and you can use your current Quarq setup as is.

Adapters are needed if you want to put your current setup with a 24mm spindle in a frame that is BB30 that would otherwise need cranks with a 30mm spindle.

Mieke
Quarq Technology

My very subjective observation is that the screw-in outboard Dura-Ace 7800 bottom bracket on my carbon Giant is no stiffer or smoother than the ancient Campy Record bottom bracket (with ball retainers removed and replaced with extra balls) in my 31-year-old Masi.

On the other hand the new drop-in bearings allow the manufacturers to widen the shell out to the cranks, purportedly to stiffen the drive section of the bike. I'll let others debate on whether this area needs stiffening.