SesameCrunch

I posted this in the recumbent forum, but somehow I think this group will be more appreciative:

I just finished converting my Downtube folding bike into a recumbent with a kit from Cruzbike.com. The kit was previously installed on my Specialized mtb, but it turned out too heavy. So, a few hours in the garage, and ta-da! A folding recumbent!

It's probably about 27 lbs, feels very light and nimble and should take the hills around here pretty well. The fold is a bit compromised right now because of the hinge in the top tube, but I'll fix that with a custom bracket eventually. Should be fun to ride!



The fold is compromised because of the seat bracket. I'll fix that with a custom bracket soon:

spambait11

Nice work, SC! Looks like you adjust your x-seam with the bottom bracket top tube(?). Doesn't look like your handlebars fold either? Did you alter your forks as well?

jur

Brilliant!

bookishboy

It looks like the front triangle moves along with the handlebars. Could you potentially eliminate the handlebars/steerer tube entirely and simply steer with your legs?

SesameCrunch

Yes, it's a moveable BB, front wheel drive system. It's kinda different to pedal, you have to get used to it. But there are certain bio-mechanical advantages which makes it worth while.

I had to lose the handlebar fold. I guess if I thought about it some more I could figure out something. But that fold isn't too big a deal for me. Also, the folding steerer/stem mechanicsm is HEAVY (over 2 lbs as I recall), so I didn't mind losing it. I don't plan to fly with this bike, just load it in my car to go somewhere.

The fork is one from the DT Non-Suspension bike. The original suspended fork weighed close to 4 lbs. The NS fork was about 1.5 lbs. I decided to go with light weight.

I think I'll be using this bike a lot!

SesameCrunch

Good observation! That's one of the benefits claimed by the designer. You can steer quite a bit with your legs alone. There are videos of people riding hands free, but I'm not one of them yet!

spambait11

Hey SC, another question: did you put spacers on the front wheel to fit the rear dropout spacing? Does Cruzbike provide a solution or did you have to come up with your own?

jasong

How much is the kit?

That's cool how the wheel actually isn't in the front fork dropouts.

Fear&Trembling

Wow, that looks great. I have seen a converted Brompton before, but the Downtube looks a lot sleeker and the recumbent kit is ingenious. How does it ride at speed?

SesameCrunch

Yes, spacers were provided which allowed me to use the front wheel in the back dropouts. I had to get a new, longer skewer.

SesameCrunch

The kit cost $375, plus $30 for shipping, so it isn't cheap. But the quality is good and I like the end result. Be aware that the kit weighs 9 lbs total. With the Downtube, I removed probably 7 or pounds worth of stuff, so the net gain wasn't that much.

www.cruzbike.com is the site for the kit. There's videos and such.

SesameCrunch

I just finished the build and have yet to take an extensive ride on it. But riding around the neighborhood, it feels really good. Light and nimble are the first thoughts that come to mind. It seems to fit my needs for a sporty bike that I can go long distance with.

I_Bike

Hey, you did it! That is sweet, great job!

HMMMM... I have a downtube...

SesameCrunch

Heh heh heh, I know the feeling.

It was actually a pretty easy install, especially compared to the mountain bike that I first installed the kit on.

The biggest factor in making it easy was the length of the cable housing. The folders have longer housing, as you know, and it made for a much easier time fitting. Also, there is long tube top very suitable for the seat pan.

The only "problem" I ran into is the hinge in the middle of the tube top. It raises up by 3/8", and it requires a little creativity working around it.

The ride is fantastic. I am really glad I did this.

spambait11

Just waiting for your fairing install and body sock attachment.

juan162

My personal tastes don't run to recumbents, but I think that yours is one I wouldn't mind giving a try. Looks great,
Juan

LittlePixel

It's a sweet install... I can't quite see how you don't veer from left to right when pedalling; Surely puttin effort into the pedals must influence the direction of travel?!?1?!?

SesameCrunch

LittlePixel:

You're absolutely right! The front wheel drive system is a little different since every pedal stroke can inadvertantly steer the bike. You end up pulling on the handlebars to counter the foot stroke. After a while you get used to the rythm and it becomes second nature. The ability to pull on the handlebars helps on the hills when you need to crank hard.

The more experienced fwd riders will tell you that they can ride/steer hands-free also because of the ability to steer with the legs. 'Course I'm not quite there yet.

I'm still getting used to starting on an incline on this bike, but perhaps that's common to all 'bents.

I'm pretty new to 'bents, so I still don't feel as strong and confident as when I'm on my upright, but I'm hoping to get to that point with this bike soon.

jasong

But pedalling in circles with your clipless setup should allow you to minimize one sides push, right?

SesameCrunch

In theory, I suppose it should. In reality, though, even the professional are pedalling mainly with the downward pedal stroke. The lifting is only about 15% of the stroke, from what I read. So, there is some "steering" going on. Having said that, the force not that strong, and you get used to countering it with your arms.

bobkat

Sesame, any more reports on how it handles? I have a DT like yours, and a Trek folder and an old Raleigh 20. Thinking of converting one of them. Is the seat comfortable? How many miles have you gone on a stretch and was it comfortable?
The main thing I would like is a folding bent that would fit in a small hatch back car for travel. My LWB bent definitely won't fit a small hatchback! Heh!

SesameCrunch

Bobkat:

It's been raining non-stop here, so I've only gone about 10 miles on the new setup. So far, I really like it. It's quick and nimble, tons better than the mtb. The 20" wheels ride better than I thought, just don't pump it up to 100psi. The seat is very comfortable after dialing it in (longest trip is 2 hours so far.). I am very happy about the change, just wished I'd done this first. Would have saved a bunch of money and time. I highly recommend it. Also, I've reconfigured the seat bracket and can now fold the thing in half, although the handlebars don't fold down anymore.

Another Cruzbike owner saw my bike and bought a DT to do the same thing!

BTW, The installation on the folder was easier than on the mtb.

So, what are you waiting for?

bobkat

I think I'll go for the Cruz conversion today. Wonder how long they are backlogged? Might try to fit it on my lighter Trek, but will see what it looks like when I get it! Thanks for the info!

SesameCrunch

Great! If you need any help, pm me and I'll be happy to try to help. There's also a Yahoo Groups forum with some very knowlegeable people who helped me get going.
https://sports.groups.yahoo.com/group/Cruzbike/

jasong

I'm really curious how well the headset/stem system on the Downtube will tolerate that kind of repeated torque. The forces you're applying are much more horizontal than vertical, which is a different than a normal bike headset is taking when someone is out of the seat and wrestling.

For pedalling in circles: I don't see how the lifting is different than on a roadbike, other than you're not lifting your leg to do it (you're more moving it laterally upward).

On the recumbent I just got, I never ever need to apply pressure to the handlebar. I baby my hands over it like feathering them on a road bike during a climb.

The setup looks cool, and definitely more portable than most other SWB recumbent designs that seem to have at least a single long boom piece that measures ~45".