Trade 2021 Q45 for 2019 or earlier

[bret]

I'm in Perth, Australia.

The front triangle adjustments (pedal distance) on the 2021 & 2019 pivot around the front wheel axle and the bottom bracket axis. Early Q bikes had separate joints inboard of the wheel and pedal axes. I'll consider a 2018 trade if that version also had the pivot around the wheel axle and the crank axle like the 2021 & 2019. That arrangement means I could put a belt drive on it some day - separate pivot joints make that impossible.

I have a neon yellow returned 2021 Q45 with all the proper specs for that model - 650b wheels, 11spd, viscous headset, etc. I added a touring rack, and I'll keep that unless the trade comes with one.

My bike has been a hangar queen - it's been on a training stand for morning exercise before work while I investigated how to put an electric motor on it. It has almost no road miles - I can count the times it's been out on one hand.

I want a Q45, with QR axles, pivots as above, in good shape and likely to last as long as what I'm trading.

Cheers.

 

[benphyr]

Q45 was the major upgrade when the Q gained the same front triangle as the S40 and v20 Before the Q45 there were QX100, Quest, Y2K, Sofrider, and Conversion kit models that all had the same one that is on the T50.

 

[billyk]

I'm trying to understand what the issue is here.

Below are 2 photos of the front triangles of
a) my long-since-sold Quest 559, showing the unusual offset joints at either end of the chainstay
b) my present 1st generation Q45 (2018), showing the chainstay joints are the BB and the wheel axle.
In both cases the BB-axle distance is fixed, unless I'm missing something.
Why does one allow a belt drive and the other not?

 

[bret]

Quest 559, showing the unusual offset joints at either end of the chainstay

Your Quest in the photo shows the chainstay as almost in a straight line - but that is only a happy accident of the boom adjustment.

You would have little reason to do this, but imagine shortening the boom as much as it's possible to accomplish. In that case, the offset joints you note will have notable angles.

The fork ends in particular enforce a right angle between the fork and the short stub extension to the closest offset joint - that angle will not change. The crank end enforces a fixed acute angle between the boom and the stub reaching back to the offset joint on the front of the chainstay. ALL of the change in angle will be distributed between the front and rear offset joints.

With this in mind, you may be able to see that this has brought the crank axle and the wheel axle substantially closer together - on the order of a centimetre or two. Draw it if you find that helps.

This has just slacked the belt and it no longer has the tension to remain engaged with it's cogs under load.

Changes in the boom length on the more recent Q bikes such as yours and later will not result in any change in the distance between the crank axle and the wheel axle. Tension-ing (for use under drive) and de-tension-ing must occur by some other mechanism - this must be possible to permit installation and removal of the belt, and adjustment to attain a value within the proper range of tension for operation. An eccentric bottom bracket seems the most practical.

In the case of the early Q, you might imagine that adjusting the boom to set the proper belt tension and then locking the boom would work and it might - but then the leg length is set and it can't be another length, so only a lucky few riders could use the bicycle.

If changes in leg length aren't independent of changes in belt tension, you lose one or the other.

 

[billyk]

Ok, that's interesting. I'm surprised it could be as much as a cm, but I see the problem. Too bad, since the offset joints would let you easily de-tension when needed, but as you say, only if the length was right.

So why do you want to trade?

As you can see from the pic, my 1st-year Q has QR axles, as they all did until this year. In fact I saved $300 by buying the very first batch ... mostly I wanted that orange color ... note the matching pedals and bar ends.

I'm intrigued by the claimed through-axle stiffening, always an issue with a swing arm bike (the Kind air shock improves this somewhat). But I'm really not wild about lime green, unfortunately.

 

[bret]

So why do you want to trade?

I haven't decided that I will - but it's possible.

The thru-axles greatly limit adding a motor to the rear. The only compatible motor on the market now is the Grin Technologies All-Axle motor, and for V2, Grin moved the cable to the left side where the disk rotor is. There is very little clearance and the spinning rotor is a saw...

Tortue's photos added to my thread show the problem and how he approached it.

The All-Axle has replaceable inserts to accommodate all (most) bicycle axle types.

Currently the wheel is in with Quantum and they are looking at how to deal with this. The suggestion is a new left-side insert with an added hook to hold the cable positively clear. I have hope they can manage this in which case I will continue with this bicycle.

I had actually ordered the 2019 with QR axles but received this. There are many hub motor solutions on the market, and they have different solutions to the cable exit, so my options are better. But I've already purchased the Grin motor, so I'm hoping Quantum (or me) can come up with a solution. The Grin is much better for braking as well - that's the real benefit of 'regeneration'. The Grin motor actually brakes according to throttle input once the brake switch is triggered. I have one on my Tern S8i. With modest behavioural changes I might never need to change pads or rotors again.