Q45 at 1000km, +/- some parts

burando

Member
After a decade of all-weather urban commuting on RWD bents, I decided last month that I've had enough of high-maintenance chainlines, and went to the LBS to buy an S40. Due to some unicycle experience, the MBB was no problem, though handsfree riding was quite wobbly. Sadly, the S40's fixed seat was too upright for my tastes and the V20 didn't look commuter-convertible, so I took home the more adjustable Q45 for a seasonal audition.

Mods: I rode the Q45 as purchased for two days. Then off came the rear rack, 38T chainring & guard, seat tilt adjustment bracket, bottle cage, light mount stub (not enough clearance for my lights), front derailleur pulley (unused, collects dirt), and kickstand (actually, it fell off). On went fenders, a 48T chainring, a mirror, bell, air horn, clock, lights, clip-on pedals, a steering lock (makes the bike rigid), and a minimalist underseat pannier rack (accommodates large panniers with good ground clearance). Pictures below. I tilted the boom and seat back to ~28 degrees and put some shaped hard-foam inserts into the seat cushion to stabilize the pelvis and provide lumbar support. The result is a commuter bike with gearing and rider geometry halfway between a V20 and an S40, but generously suspended. Given the condition of local roads this winter, that's my sweet spot.

Speed: I did some roll-down timings and found that the Q45 is slightly slower then my previous commuter, a bombproofed Bacchetta Giro 26ATT whose higher bottom bracket and "superman" handlebars afford a more aero position. Could also be that the Giro just has better tires and more weight (it's kitted to carry a adult passenger), but it routinely overtakes a Silvio 2.1 on a flattish part of the route home. The Q45 does seem to be a better climber, except on very steep grades or wet hills, where front wheel slippage can completely kill forward momentum. At present, the Q45 adds ~2 minutes to my 16km morning commute. Totally worth it, considering how nicely it smooths out rough roads that I avoid on hardtail bents.

Forks & fenders: The steering fork is "pinched" and the chainstay fork is not. WTF (what's that for?) From a heel-clearance point of view, the wrong fork is pinched. For fenders, it's almost a deal-killer: The steering fork is too narrow to accept standard fenders (or my favorite tire) and the chainstay fork has no fender mount points. I used a heat gun to soften a polycarbonate rear fender and jam it into the pinched fork, and UV-robust zip ties to fix it to the unpinched fork. Getting a (front) fender onto the rear wheel required similar improvisations.

Tires: IMHO the main determinant of bike performance. The soft rubber tread on the stock Maxxis tires has a killer combination of high rolling resistance and poor traction. There's an alarming amount of tire slippage when powering out of a traffic stop or up a hill. The tread also collects pebbles to the point of getting noisy on the rare quiet road. Looking forward to replacing these with 50mm Schwalbe Marathon Supremes. And a wide fork.

To do: (1) Handlebar replacement. Ideally my hands would be higher, more centered, and in-plane with the steering axis, but the boom mount says no can do. Might try bullhorn or dirt-drop handlebars, tipped vertically. (2) Adjustable seat pan bracket. I'd be more aero and better leveraged if the seat pan were further back, lower, and slightly angled. Also safer, as I've learned that the rear wheel goes airborne during emergency stops. After some tinkering I concluded that a new bracket will have to be machined. (3) Better parts for all-weather commuting. Six weeks in and the chainring bolts are rusting and the drivetrain is showing wear.

Misc: (A) If the kickstand were 1cm longer I might have kept it. (B) The retro-reflective detailing doesn't really work under clear-coat (which frustrates the microbeads' total internal reflection). (C) The wheel flop could be traded off for a little less trail (something to keep in mind when replacing the fork). (D) The short s-curve in the rear brake cable routing is a head-scratcher. (E) The bike came home with a variety of assembly errors, some merely sloppy, some dangerous. Props to the LBS for fixes.

Now to pictures:
Conspicuity tape to make the bike pop in headlights on winter nights:


Mirror, horn, & bell had to be mounted on or near the brake hoods for knee clearance:


The steering lock is simply a hex key that goes through the fork bridge to a small machined receiver:


The pannier rack is a carbon fiber tube on two small aluminum standoff blocks. Unobtrusive & weighs <50g:


Hope this is useful to fellow commuters. Tailwinds, all.
 

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onmyback

Active Member
Your experienced parallel mine. My Q45 replaced and old Vision VR45 (20x26 USS) that I used for all weather commuting. I also have a highracer for sportier days.

Do you pull the hex key out and stow it somewhere, while riding? I have the rear pannier rack, which with a little suspension compression, holds the bike vertical in bike lockup racks. I've arranged an ugly piece of old inner tube, to help the fork stay straight, so that I don't bump neighbouring bikes.

I considered going with the underseat pannier rack, but it gets mighty wet in our rainy season, which would sometimes make the pannier bottoms drag in flooded areas. I suspect my rear rack has a larger impact on handling and it really doesn't like being loaded unevenly (e.g. single pannier) compared to other bikes.

The need for two "rear" fenders was a bit annoying and added expense, since fenders are usually only sold in sets. I was at my 4th LBS before finding a fender that would work on the front wheel. I ended up using a piece of galvanized steel strapping (comes in rolls, with pre-punched holes) for the forward front fender mount. I also have bits of rubber taped onto the inside surfaces of the chainstays, with clear Gorilla tape, to prevent rattling. It easily bends a bit, to allow minor boom length adjustments, but it is rather ugly. PS; I've also applied Gorilla tape to the inside of my rear swing

I haven't done any roll-down tests, but I've actually been quite happy with the stock tires and the bike seems to coast forever. Given the bike has suspension, they are plenty wide for me.

I too would be happier with the seat slightly further back, both to keep the back wheel on the ground during hard stops and because I have the boom completely extended (I have a pretty average X-seam). I may try your foam insertion to make the seat a bit more ergonomic.

I'm not sure how you plan to replace the fork. It's dropouts are custom CruzBike style, to accept and centre the chainstays.

Cheers
Colin
 

benphyr

Guru-me-not
Just to confirm that the seat pan has 3 positions and you are already (both) using the rear seat pan, right?

@burando Nice build. Can you show some pictures of the seat cushion/foam modifications that you did? And how is your water bottle mounted? Mine eventually bounces out if I have it under the seat, doesn't it fall out?

Sounds like good analysis, seems to match with what I know from my experience on the QX100 too.
 

Rampa

Guru
You may be able to get away with reversing the seat mounting base 180, if your OK with a bit more nose-up. That moves the seat back and lower.
 

super slim

Zen MBB Master
After a decade of all-weather urban commuting on RWD bents, I decided last month that I've had enough of high-maintenance chainlines, and went to the LBS to buy an S40. Due to some unicycle experience, the MBB was no problem, though handsfree riding was quite wobbly. Sadly, the S40's fixed seat was too upright for my tastes and the V20 didn't look commuter-convertible, so I took home the more adjustable Q45 for a seasonal audition.

Mods: I rode the Q45 as purchased for two days. Then off came the rear rack, 38T chainring & guard, seat tilt adjustment bracket, bottle cage, light mount stub (not enough clearance for my lights), front derailleur pulley (unused, collects dirt), and kickstand (actually, it fell off). On went fenders, a 48T chainring, a mirror, bell, air horn, clock, lights, clip-on pedals, a steering lock (makes the bike rigid), and a minimalist underseat pannier rack (accommodates large panniers with good ground clearance). Pictures below. I tilted the boom and seat back to ~28 degrees and put some shaped hard-foam inserts into the seat cushion to stabilize the pelvis and provide lumbar support. The result is a commuter bike with gearing and rider geometry halfway between a V20 and an S40, but generously suspended. Given the condition of local roads this winter, that's my sweet spot.

Speed: I did some roll-down timings and found that the Q45 is slightly slower then my previous commuter, a bombproofed Bacchetta Giro 26ATT whose higher bottom bracket and "superman" handlebars afford a more aero position. Could also be that the Giro just has better tires and more weight (it's kitted to carry a adult passenger), but it routinely overtakes a Silvio 2.1 on a flattish part of the route home. The Q45 does seem to be a better climber, except on very steep grades or wet hills, where front wheel slippage can completely kill forward momentum. At present, the Q45 adds ~2 minutes to my 16km morning commute. Totally worth it, considering how nicely it smooths out rough roads that I avoid on hardtail bents.

Forks & fenders: The steering fork is "pinched" and the chainstay fork is not. WTF (what's that for?) From a heel-clearance point of view, the wrong fork is pinched. For fenders, it's almost a deal-killer: The steering fork is too narrow to accept standard fenders (or my favorite tire) and the chainstay fork has no fender mount points. I used a heat gun to soften a polycarbonate rear fender and jam it into the pinched fork, and UV-robust zip ties to fix it to the unpinched fork. Getting a (front) fender onto the rear wheel required similar improvisations.

Tires: IMHO the main determinant of bike performance. The soft rubber tread on the stock Maxxis tires has a killer combination of high rolling resistance and poor traction. There's an alarming amount of tire slippage when powering out of a traffic stop or up a hill. The tread also collects pebbles to the point of getting noisy on the rare quiet road. Looking forward to replacing these with 50mm Schwalbe Marathon Supremes. And a wide fork.

To do: (1) Handlebar replacement. Ideally my hands would be higher, more centered, and in-plane with the steering axis, but the boom mount says no can do. Might try bullhorn or dirt-drop handlebars, tipped vertically. (2) Adjustable seat pan bracket. I'd be more aero and better leveraged if the seat pan were further back, lower, and slightly angled. Also safer, as I've learned that the rear wheel goes airborne during emergency stops. After some tinkering I concluded that a new bracket will have to be machined. (3) Better parts for all-weather commuting. Six weeks in and the chainring bolts are rusting and the drivetrain is showing wear.

Misc: (A) If the kickstand were 1cm longer I might have kept it. (B) The retro-reflective detailing doesn't really work under clear-coat (which frustrates the microbeads' total internal reflection). (C) The wheel flop could be traded off for a little less trail (something to keep in mind when replacing the fork). (D) The short s-curve in the rear brake cable routing is a head-scratcher. (E) The bike came home with a variety of assembly errors, some merely sloppy, some dangerous. Props to the LBS for fixes.

Now to pictures:
Conspicuity tape to make the bike pop in headlights on winter nights:


Mirror, horn, & bell had to be mounted on or near the brake hoods for knee clearance:
7806-52689170104c6e46c18019274edf7342.jpg


The steering lock is simply a hex key that goes through the fork bridge to a small machined receiver:


The pannier rack is a carbon fiber tube on two small aluminum standoff blocks. Unobtrusive & weighs <50g:


Hope this is useful to fellow commuters. Tailwinds, all.

I really like your simple cheap steering lock!

How much do you think the seat height could be lowered, by drilling higher holes in the two seat base brackets?
 

burando

Member
Responses:

Seat inserts (@onmyback, @benphyr): Both cut from a 5cm-radius half-cylinder of firm closed-cell flotation foam (at left):

The arch (middle) gets stuffed inside the seat cover under the cushion for lumbar support; the half-pyramid (right) similarly goes into/under the nose of the seat between the legs. So far they haven't slipped.

Steering lock (@onmyback, @super slim): The hex key is fattened with a jacket of yellow heat-shrink so that it can be nudged out of the receiver and held in place by friction while riding. Remains to be seen how well this works at temperature extremes, so I also put retaining indents into the fender.

Seat pan (@benphyr, @Rampa): I drilled some additional holes so that the front edge of the seat pan can sit 2cm behind the front of the mounting bracket. Tried reversing the bracket; too much nose up. Lowering the bracket would involve more than just drilling it. I will likely machine a replacement that lowers the seat ~2cm in the front and ~4cm in the back.

Fenders (@onmyback): I used set of standard 50mm (~2") fenders, taken off an old playa bike. They're rock solid since they're heat-formed to fit the Q45 frame. I did have to extend the front fender (on the back wheel) with a bit of lightweight polyethylene to prevent tire-spray.

Water bottle: (@benphyr): The underseat bottle is a pressurized air reservoir for my air horn. If I wanted a water bottle, I'd probably attach a cage to the steering tube with hose clamps or industrial-strength zip ties.

Panniers (@onmyback): Unlike the Terracycle rack, the minimalist rack sits above the shock, putting the bottoms of my largest bags roughly level with the bottom of the brake rotors. So I have no qualms about cycling through deep water (other than hidden potholes). The load center of gravity sits <10cm from the exact midpoint of the two wheel hubs, with no perceptible effect on handling.

BTW, I made two racks with 12mm tubing, then discovered that some of my bags have narrower hooks. These could go on somebody else's bike ...

 

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onmyback

Active Member
Just to confirm that the seat pan has 3 positions and you are already (both) using the rear seat pan, right?

@burando Nice build. Can you show some pictures of the seat cushion/foam modifications that you did? And how is your water bottle mounted? Mine eventually bounces out if I have it under the seat, doesn't it fall out?

Sounds like good analysis, seems to match with what I know from my experience on the QX100 too.

My seat pan frame is slotted. The seat pan is as far back as it goes. It might be possible to reverse it, but that would really tip the front of the seat up.
 

billyk

Guru
Nice build.

Your next upgrade should be the Kind air shock (search these forums for many reports). Less pogo, more control, the frame becomes more rigid. Way, way lighter! Pretty cheap, too, about $75.

I use a similar (think) closed cell flotation foam for similar seat-shaping. My experience is that it eventually crushes if your weight is on it and becomes flat. Not that eventually in fact. Unless you have a better kind. In that case I'd like know where to get it.
 

burando

Member
5000km update: I moved the seat down & back 4cm by replacing all the seat brackets with some drilled aluminum angle bracket. Seems to make the bike stiffer and faster -- smoked an S40 yesterday ;-). Thinking about buying a V20 chainstay to raise the BB to a more aero position. Also replaced the carbon fiber in my underseat racks with aluminum; pics below for @Giloun. The seat-shaping foam is holding up pretty well but yes, @billyk, I expect to replace these annually. Looking forward to replacing the shock. Can anyone volunteer the right model # for a Q45?

Pics: The seat is lower and further back:
IMG_4514.JPG
The underseat rack from the side and back:
IMG_4509.JPG
IMG_4510.JPG
Once you know your preferred geometry, angle bracket makes a lighter and stiffer frame-to-seat connection than the original hardware:
IMG_4508.JPG
 

burando

Member
As per @billyk I put on an air shock (DNM's new AOY-38RC). Does a lovely job, and has a lockout which has been great for aggressive climbing with heavy baggage loads. The only issue is that the Q45's skewed mount points will reduce any shock's mechanical advantage, so you have a choice between higher shock pressure or reduced piston travel. I split the difference and let the bike sit lower (under load). Might even be getting a little aero advantage there.
 

jond

Zen MBB Master
On air shock, how does DNM AOY-38RC compare with the Kind Shock KS A5-RR1?

Very very favourably fitted on a challenge hurricane.

I did a review on this forum. It’s titled “ cheapish rear shock comparison “ compared 165mm cheap shocks a dnm DVD 22 coil over and the kind shock rr1 and the dnm aoy 38 rc.

In a nutshell the air dnm is not as light as the kind shock is a little more expensive but has lockout and rebound adjust. Well worth it. Buy it. I found its performance vastly superior when fitted to hurricane .
 

burando

Member
Added another set of minimalist pannier racks slightly higher up and behind the seat. Can get 4 full-sized bags on the bike now. Upside is that the seat now sits at ~25° fully loaded and the bottom bracket is well above the seat pan, which seems to improve my leverage on the pedals. Downside is that this has confirmed my suspicion that something up front (chainring? boom?) is flexing under heavy pedaling forces. Also have to be careful not to bottom out the shock when mashing up steep inclines with a lot of weight in the bags.
Q45_rack2.jpg
 

benphyr

Guru-me-not
(1) Added another set of minimalist pannier racks slightly higher up and behind the seat.... (2) Downside is that this has confirmed my suspicion that something up front (chainring? boom?) is flexing under heavy pedaling forces. (3) Also have to be careful not to bottom out the shock when mashing up steep inclines with a lot of weight in the bags.
1) Love it. Can you post more on how you made these minimalist racks?
2) How did you confirm flexing? Do you have a measurement of how much force/power you are putting down when you say "heavy pedaling forces"?
3) Is that an air shock? Can you increase the pressure in the shock when you are going to be fully loaded?
 

super slim

Zen MBB Master
Added another set of minimalist pannier racks slightly higher up and behind the seat. Can get 4 full-sized bags on the bike now. Upside is that the seat now sits at ~25° fully loaded and the bottom bracket is well above the seat pan, which seems to improve my leverage on the pedals. Downside is that this has confirmed my suspicion that something up front (chainring? boom?) is flexing under heavy pedaling forces. Also have to be careful not to bottom out the shock when mashing up steep inclines with a lot of weight in the bags.
View attachment 8507
Stunning idea for the pannier support and great simple design!!!
 

burando

Member
Re: @benphyr 's questions about seat-tube-mounted minimal rack:
1) Making the rack: Cut 2 C-clamps from 1/2" aluminum plate, drill holes for tightening bolt and rails as in picture below. Slide onto seat tube, slide in 3/8" rods, tighten bolts to lock it all together.
2) Front end flex: If I put the chain on the smaller chainring and sprint or climb, it will scrape the larger chainring when the right pedal is at peak torque.
3) Air shock: DNM's AOY-38RC. Nice, but already pumped high to compensate for poor leverage afforded by the frame mounts. I just lock it out for steep climbs.

The rack has be rock solid and super-convenient, but ironically I'm now looking at moving the pannier bags to the front wheel because spin-outs on winter roads has become too much of an annoyance.
rack_clamp.png
BONUS: A recumbent bike song sung to me at party last night
 

super slim

Zen MBB Master
Re: @benphyr 's questions about seat-tube-mounted minimal rack:
1) Making the rack: Cut 2 C-clamps from 1/2" aluminum plate, drill holes for tightening bolt and rails as in picture below. Slide onto seat tube, slide in 3/8" rods, tighten bolts to lock it all together.
2) Front end flex: If I put the chain on the smaller chainring and sprint or climb, it will scrape the larger chainring when the right pedal is at peak torque.
3) Air shock: DNM's AOY-38RC. Nice, but already pumped high to compensate for poor leverage afforded by the frame mounts. I just lock it out for steep climbs.

The rack has be rock solid and super-convenient, but ironically I'm now looking at moving the pannier bags to the front wheel because spin-outs on winter roads has become too much of an annoyance.
View attachment 8687
BONUS: A recumbent bike song sung to me at party last night
Any chance of a dimensioned drawing, so others could make these great simple brackets!!!
Would these brackets be suitable in PETG 3D printed?
 

burando

Member
Any chance of a dimensioned drawing, so others could make these great simple brackets!!!
Would these brackets be suitable in PETG 3D printed?

Here's an STL file and the OpenSCAD file that generated it. It's parametric CAD so you can play with all the dimensions and generate new STLs.

I made mine out of 6061 aluminum; for PETG you'll want to thicken the clamp, print 100% solid, and probably melt in a brass threading insert instead of tapping threads directly into the plastic. Good luck!

PS You might want to strip off the ".txt" suffixes of the file names; I added them to make the files palatable to the uploader.
 

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