Dynamic Boom Question...

[Postapocalypsia]

Hi learned folk,
I am curious about the triangulation properties of the dynamic boom on the Q45. I ride a Q559 v2 where the boom attaches lower down, and I was wondering if I was losing uphill power if the riser tube was flexing under stress. If I duplicated the bracket tensioning the diatech business and raised the boom and secured it at the top, this would create a truer triangle, raise the pedals a little and allow the seat to go back a bit, all of which seems good to me.
I have attached a pic where I roughly photoshopped the effect.
Is this a folly or potentially advantageous?
I am also trying out some bigger tires for a laugh - 1.95 on the original rims. They fit well with just a whisker of filing for rear wheel clearance. The result is easier passage and better traction over bumps, also offset by a 11-36 cassette which helps.
Any enlightenment on front end dynamics would be appreciated!
...and Happy New Year to you all!

 

[Rampa]

You should just try it both ways.
There is the potential that your legs will be flexing the riser more, simply because it's a longer lever that way. Having the clamp just at the the top of the steerer makes the riser the shortest lever possible for your legs. But if you have your handlebars the right width, your arms will properly counterbalance your legs (wider bars is more leverage than narrower cranks).

 

[Postapocalypsia]

Thanks Rampa, I figured I would keep the boom adjustment shorter and just sit further back.
I use Soma Sparrow handlebars which I find quite efficient - not too wide but with a nice kink for plenty of knee room.

 

[castlerobber]

There are old threads about the "energy-sucking handlebar-on-a-stick" where this is discussed. You might be interested in the "Emeljay mod" . I'm linking you to a particular post, but there's a whole thread full of details.

 

[billyk]

In the threads @castlerobber mentions, and others, there is also discussion about the spring shock in the head tube causing flex and power loss. Definitely worth searching the Q forums as these topics have been well gone over.

Try getting the front end assembly (head tube/fork, and boom/slider) from the QX100. In addition to omitting the useless (my experience) spring shock, the QX100 boom/slider is beefier.

I did this on my Q2 and it stiffened things up pretty well. The parts weren't too expensive.

Try Rose City Recumbents in Portland, and tell them exactly what you're trying to do, and if there's something else you need (bolts at the bottom of the fork? ... as I remember these also need replacing).

 

[Postapocalypsia]

Thanks billyk, I had a good trawl through the threads castlerobber mentioned and found plenty of inspiring options. One of the issues I have is arm position...I really benefit from having almost straight (and low) arms when riding, and finding a good combination of handlebar, stem height, and seat position is tricky. I will look into the QX100 front end for sure thanks, but first I am trying the low budget tweaking approach. I have found a combination of Soma Sparrow handlebars and a longer adjustable stem allows me to lower the anchor point on the riser bar by around 95mm which should, in theory, reduce the flex. This also makes a more direct line between my hands, knees, and feet when pedalling which is great.
I have already replaced the sprung front forks, which made a difference too.
Just out of curiousity...I wondered if the CB folk had considered a hybrid of the S40 and the Q45 - basically an S40 with a suspended tail. If they brought out one of these I would save up for that!

 

[super slim]

Thanks billyk, I had a good trawl through the threads castlerobber mentioned and found plenty of inspiring options. One of the issues I have is arm position...I really benefit from having almost straight (and low) arms when riding, and finding a good combination of handlebar, stem height, and seat position is tricky. I will look into the QX100 front end for sure thanks, but first I am trying the low budget tweaking approach. I have found a combination of Soma Sparrow handlebars and a longer adjustable stem allows me to lower the anchor point on the riser bar by around 95mm which should, in theory, reduce the flex. This also makes a more direct line between my hands, knees, and feet when pedalling which is great.
I have already replaced the sprung front forks, which made a difference too.
Just out of curiousity...I wondered if the CB folk had considered a hybrid of the S40 and the Q45 - basically an S40 with a suspended tail. If they brought out one of these I would save up for that!
View attachment 8741

AND you could then pack the rear suspended S40 in a 26"*26"*10" US airline sized box/Bag to save $220/leg in excess luggage!

 

[Postapocalypsia]

What do you think slim, good idea? Would you buy one?

 

[super slim]

What do you think slim, good idea? Would you buy one?

If I needed a new Cruzbike, the wide tyred S40, with a removable rear suspension, would be my pick!

I have two Silvios, a V1.0 45 degree Aluminium seat as part of the frame, with air front fork, and my air bag rear suspension, both using the patented One Speed titanium/CF flexible forks, and a Silvio V3.0 with a 28 degree CF removable seat, with air front fork, and stiff (At this stage poly) rear suspension, both using the patented One Speed titanium/CF flexible forks!
The V3.0 has foam added between the seat and the mesh padding to approx 35 degrees !

The V1.0 will NOT fit in a 26"*26"*10" box as the fixed seat stops wheels going either side of it!
The V3.0 28 deg. will fit in a 26"*26"*10" box with the cruzbike removable CF seat!

 

[Giloun]

Just out of curiousity...I wondered if the CB folk had considered a hybrid of the S40 and the Q45 - basically an S40 with a suspended tail. If they brought out one of these I would save up for that!
View attachment 8741

I have shortened the steerer tube of my Q45. Does it make it more like a suspended tail S40?
https://forum.cruzbike.com/threads/shortening-the-steerer-tube-of-q45.12716/