Q45 (100 miles) vs Q2 (9000) compared

[billyk]

I have more than 9000 miles on my Q2 (upgraded to QX100, see below). Now I've done about 100 miles on my new Q45. Most of these miles are on my daily commute (5 miles each way, about 2/3 on city streets, 1/3 on a bike trail). Most of the rest are errands and shopping. This post is a comparison of the two bikes, based on that experience.

I bought an early-ish Q2/559 in late 2011. Seattle is hilly, and I climb a 275-foot hill on my way home every evening. It was apparent that the frame flexed quite a bit under heavy load (see measurements of this on the thread "Quest frame flex tested" http://cruzbike.com/forum/threads/quest-frame-flex-tested.7794/). We argued inconclusively here about where the flex was occurring: handlebars bending, steer tube twisting, boom/slider bending, a bit of play in each of those many joints, ...). Someone here called it an "energy-sucking handlebar on a stick".

After that testing, I made three upgrades that improved this greatly: replaced the stock shock with an air shock, replaced the original front shock steer tube/fork with the rigid QX100 one, and got a beefier boom/slider. These are essentially an upgrade to a QX100, and made a lot of difference, but one of my main motivations for getting the Q45 was the much better-designed and stiffer boom/slider. And indeed it is. The Q45 is virtually flex-free, even pumping up a 10% grade. Brilliant.

I mounted the old Q2 fairing on the Q45 (it's my raingear; I commute year-round), and it is a sensitive indicator of flex between the handlebars and bottom bracket: any twist on the plastic is highly evident (see "New homemade fairing for Quest" http://cruzbike.com/forum/threads/new-homemade-fairing-for-quest.6959/). The Q45 is close to dead rigid.

Specific differences (Q45/Q2):
- 1.75 tires vs 1.5 (same pressure, 60lb)
- longer wheelbase by about 2 inches
- much slacker head angle (70-deg vs 78, by my crude measurement)
- longer shock (165mm vs 125)

The Q45 is way more bump-friendly. Even with the air shock, the Q2's ride on Seattle's bumpy, potholey streets wasn't great. The most dramatic difference I note with the new bike is how much more pleasant the ride is, and I'm on the same route every day so I know these bumps well. I'm not sure why this is: The Q45 has the stock 1.75 tires pumped up to 60lb, which doesn't seem that different from the Q2's 1.5 tires at the same pressure. Maybe the longer travel of the Q45 shock? The slacker head angle? Whatever, it is excellent.

Overall, the ride quality is a step up, for sure.

I find that I am faster on the flat, by a lot, 10% or more without seeming to work harder. On the other hand I am no faster (maybe even slower) uphill. I would have thought that the rigid front end would improve my uphill speed. Nope. This might be because of the spring shock, which I found on the Q2 was an energy-sink when climbing; I'll replace it with an air shock to see. It could also be because of my riding position: I have the Q45 seat as far back as it can go and the handlebars as far forward as they can go (right at the pivot clamp), and it is still closer than the Q2 seat was to its bars. I got used to a much more open-body, arms-outstretched riding position and can't make that happen on the Q45. Not sure what to do about that ...

I miss the SRAM internal hub, heavy as it was. Riding in urban traffic like I do, there are a lot of quick and unexpected stops, and the ability to shift into low gear while stopped got used a lot. But yeah, it's a heavy, clunky thing that made the front end even more unwieldy.

I also find myself riding the Q45 in high gear most of the time, at about 16-17mph. I can push it to 20, but the cadence at that speed is too high for me to keep it up for long. I will probably get a larger chainring, since I bought the Q45 with a 42-tooth sprocket that is plenty low, so I have room to increase the gearing.

I would have thought the slacker head angle would make the bike "more stable", since a slacker angle should increase the trail and thus make the bike want to track straight (see Wikipedia "Bicycle dynamics"). I have not measured the trail (yet), but don't notice much difference; if anything, I find the Q45 "twitchier". On the other hand, it is equally easy and comfortable to ride the Q45 no-hands. But the head angle difference is really large; I wonder what the theory was behind making that change.

For the first time, I have a kickstand that holds the bike up even when loaded with groceries or my work stuff. I never found one that would do that for my Q2. Not to be taken for granted!

Coming experiments (will be reported here):
- Air shock
- Weigh the bike with me on it, each wheel separately; compare Q2
- Measure the trail on both bikes (not so easy to do accurately)
- I might even take the opportunity to put the Q2 swingarm on the Q45 (looks like the mounts are identical). That will have the effect of lifting the rear end of the frame, increasing the head angle, and decreasing the trail. Thoughts?

Did I mention that the Q45 is absolutely gorgeous? Just from appearance sake, getting rid of the complex front end of the Q2 is a big improvement.

And I will soon have a Q2/QX100 for sale ... lovingly maintained.

 

[Rampa]

Try reversing the plate on the bottom of the seat. That may allow greater rearward adjustment.

 

[dtseng]

Thank you for such informative post which is very important for those of us procrastinating on owning the new Q.

Move the seat pan as forward as possible and back rest as low as possible. That will give you more cockpit space and therefore, more aero and climbing better.

How about do the experiment: inter-change the front triangle. You'll never know that might give Q2 200% improvement in performance.

 

[Brad R]

Try reversing the plate on the bottom of the seat. That may allow greater rearward adjustment.

If the seat mount is similar to the T50, you can use just two bolts on the seat pan instead of 4. You can move the seat back by using the front two holes in the seat pan and the rear two in the mounting plate.

However, this might interfere with getting the seat back as reclined as you want.

 

[billyk]

How about do the experiment: inter-change the front triangle.

I'm pretty sure that, except for the braze-ons for the seat mount, the Q45 frame is identical to the earlier Q2 frame. The head angle is changed because the shock angles back, tilting the frame back. So replacing the front triangle on the Q2 would be the same experiment as replacing the swingarm on the Q45!

 

[benphyr]

@billyk

I thought I remembered seeing somewhere in the lead up to the Q45 release (but couldn't find it in the promotional emails) that the only difference to the main frame was the rear end being lengthened for stability/climbing traction and to move the rear shock mount rearward to accommodate the longer, standard size shock. If the info above is correct then it should not have changed the head angle/trail however, this is all from my memory and without any measurements. Can you measure the height from ground of the pivot point for comparison along with other comparisons you are making?

Also, the change in front triangle could seriously change the feel of the front end even if the technical elements are still similar just because the pieces flex differently. Your Q2X100 might actually weigh less after your changes than the new stock Q45.

Some food for thoughts. Thank you for sharing your experiences.

 

[dtseng]

I measured from the picture (may not be accurate): pivot height from ground 510 mm, axle to pivot 610 mm, head tube angle 70 degrees, trail 70 mm. Q2 with suspended front forks also has 70 degrees head tube angle. Axle to pivot 589 mm. Ben's "above info" is correct. Only the swing arms are elongated in Q45. Replacing the fork of Q2 with non-suspended one may increase the head tube angle.

 

[billyk]

the only difference to the main frame was the rear end being lengthened for stability/climbing traction and to move the rear shock mount rearward to accommodate the longer, standard size shock. If the info above is correct then it should not have changed the head angle/trail

"the above info" is correct, but it DID change the head angle because the rearward shift of the shock mount results in lowering the height of the swingarm-frame pivot point, thus tilting the head tube back.

Imagine lengthening and shortening the shock on a Q2: The head tube would tilt forward and back. The way the shock is mounted on the Q45 is effectively like shortening the shock on the Q2.

I'm on work travel this week and all of next, home briefly over the weekend. I will measure the height of the swingarm pivot on the two bikes ... betcha the Q45 is lower.

 

[billyk]

I'm on work travel this week and all of next, home briefly over the weekend. I will measure the height of the swingarm pivot on the two bikes ... betcha the Q45 is lower.

Swingarm pivot height: Q2=22.75". Q45=21".
That's what accounts for the Q45's shallower head angle. The same frame lowered 1.75" in the rear.

Seat pan back to handlebar center (seat all the way back, bars all the way forward):
Q2=24". Q45=20.25".
That's the difference in the riding position. I'm 3.75" closer to the bars.

When I get back from the next trip I will try @Brad R's suggestion to shift the seat back using only 2 of the bolts. Thanks.

Considered @Rampa's idea of reversing the plate below the seat, but that would tilt the pan back much more.

@dtseng's sketch is wrong in several particulars, especially in putting the swingarm pivot in a different place. The two frames are identical, it is the swingarm only that has changed.

 

[Robert Holler]

There are definitely some nuanced changes to the Q45 frame over the old Q frame - they are 98% similar but the small changes made a big difference in ride quality.