Tuesday, August 2, 2011

Evolution of a Vision R40 SWB Recumbent

For a first post on a new blog, it would seem prudent to choose a project bike that had some interesting options and results. 

I don't think any of my bikes have seen much more of a renovation than my pair of 1994 Vision R40 recumbent bikes, purchased in 2009.

The Vision R40 came in two configurations: short wheelbase and long wheelbase (sometimes called mid wheelbase).  Both have a 26" rear wheel and 16" front wheel.  One issue I had right away with the bikes was that they have the shortest wheelbase of any bike I've ever ridden (at least since I left training wheels behind)!  This makes them what you'd call "very responsive", or probably better described as "twitchy".

Interestingly enough, the short wheelbase version can be converted to a long wheelbase just by swapping the front boom for the style that has a head tube ahead of the bottom bracket.  The front fork can then be relocated to the forward position and a steering linkage ties the fork and the handlebar together.  One such longer boom was included in the box of parts that came with the pair when I purchased them, so I converted it to its longer configuration.  This made the ride much more stable at speed, and the added length smoothed out the ride noticeably as the chromoly frame soaked up the bumps.

On the whole, both bikes rode very well.  They have full mesh seats which are comfortable and extremely breathable.  Adjustable recline angle, pivoting handlebars and rackmounts make them very versatile machines.  They are on the lighter side for steel-frame recumbents, and their drivetrain is very simple and efficient with no power-side idler and only one idler wheel on the non-power side.  They can be set up as over seat steering over under seat steering, whatever your preference happens to be.

For cruising and touring the LWB seemed well-suited, but I had speed comparisons on my mind and the added weight of the boom and steering linkage seemed counter-productive... so I began working with its SWB sibling.  Handling was definitely an issue over 25mph, but nothing too worrisome - plus, I don't spend a great deal of time at that speed anyway.  What I was more concerned with was the flatland performance.  In my estimation there were a couple things working against this machine.  First, the 16" front wheel did not do very well with bumpy surfaces, and some of the trails I was riding were bumpy enough to cause me to slow measurably.  Secondly, the riding position was not terribly aerodynamic - even with the seat quite reclined.  The bottom bracket (where the front crankset resides) was just too low for the seating position and presented too much surface area to the wind. 

I decided to solve both problems with one solution - a larger front wheel.  I picked up an inexpensive steel (1" threaded) fork, had it cut to the right length, and found a used 20" front wheel that was still fairly true and rolled adequately.  This conversion was quite quick and easy as the new fork positioned the brake pads of the old brakes nicely in line with the new wheel's rim.

The new wheel definitely appeared to improve the aerodynamics by raising the bottom bracket up and bringing the pedal circle more in line with the wind shadow of the body, which hopefully would translate into lower wind resistance.  The first ride out brought about some realizations.  First of all, I'm not a tall rider at 5'6", the new wheel and fork had raised the bottom bracket height enough to make flat-footed stops and starts a bit less comfortable than they had been with the smaller wheel.  Once moving, though, the position certainly felt better.  The second observation was a pleasant one after analyzing the ride data - the bike was 5-10% faster.  Now, I could go into the comparison rides and methods, but we all know that comparing bikes to one another across days/weeks/energy levels is virtually impossibly to fully quantify.  I'll leave it to say my numbers were quite a bit improved.

This successful modification led to more theorizing on what to improve upon next.  Before I jumped into any other radical innovations, I first upgraded the drivetrain.  A new rear wheel w/ 9-speed wide-range (11-34) cassette, new 9-speed chain, new Shimano Deore rear derailleur and Shimano integrated brake/shift levers made shifting more precise while expanding the gear range (from the original 7-speed drivetrain).  I also changed out the front crankset for a Sugino XD600 triple (24-36-50) with 152mm crank arms.  I have found that my short legs prefer a shorter crankset on recumbent bikes than on diamond frame bikes.  I ride with a 165mm crankset on my road bike, but that length bothers my knees on the 'bents.  I've had good luck with the Sugino cranksets, they're moderately priced ($110-ish) and it's hard to find a wider range triple unless you customize.  I find that my speed doesn't change much with the shorter crank arms, but the comfort level is much improved.

After a number of rides under my belt with this 26/20 configuration, I once again felt the need to push the speed limits of this machine.  I first tried another size jump in front wheel diameter.  I tracked down a larger fork that would fit a 26" front wheel and swapped it out.  With the dual 26" wheels, the pedal circle moved further upward and almost fell in line with the body of the rider just as I'd hoped.  What I hadn't hoped for is as much height difference in the seating position for my short stature.  What had been a stretch to stop/start with flat feet before turned into a stretch to even reach the ground tiptoed.  On top of that, the wheel diameter was large enough that the tire actually overlapped the circle of the crank arms.  This meant that if I turned the wheel more than a few degrees while pedaling the crank arm (or my foot) would hit the front wheel.  Now, recumbent riders are generally accustomed to "heel strike" because of this positioning and it can generally be mitigated by kicking your heels out to the side when turning sharply.  Crank strike, on the other hand, is a big problem and can stop you dead in your tracks if not extremely careful.  I eased the bike out for a couple of time trial rides and found that the benefits (3-5% speed gain) didn't outweigh the drawbacks (paranoia when turning).  Time to click the "undo" button.

Back at the drawing board with the bike safely back to its 20" front wheel configuration, I decided to try another method to mitigate wind resistance: a fairing.  As luck would have it, I found a Vision Lexan or Plexi or some kind of clear plastic fairing with mounting hardware on craigslist.  It was a bit heavier than I'd imagined, but it had a lot of surface area as well.  Riding with a fairing is a bit different as vision is a bit impaired even with the clear plastic - it was a bit hard to see the pavement closer than 5 feet in front of the bike.  The fairing also made it warmer to ride - nice on a cool crisp fall morning - not so nice on a humid summer day.  Time-trial-wise, the fairing added another 5-10% to the flatland speed when the wind was light or off the nose/tail.  Cross-winds necessitated "fighting" the bike a bit because of the large surface area of the fairing and caused speeds to dip to levels at or even below those of the unfaired bike.  Climbing also slowed a bit (5-10%) with the fairing as the added weight worked against it.  None of my routes were terribly long and straight, and coupled with the midwest's proclivity for moderate-to-high winds, this was not an ideal faired bike environment.  Having not been quite as impressed with the performance gains as I'd hoped, I left the bike in the unfaired configuration for the bulk of the time unless comfort dictated its use (primarily cooler weather).

At this point I decided the unfaired 26/20 configuration of the Vision R40 was the most efficient possible while still being useable for someone of my stature.  Overall the bikes both rode wonderfully and were great recumbents.  I rode the SWB model on two long charity rides and it performed perfectly and made the trips much more comfortable than any diamond frame would have.  But, with the projects exhausted the addiction set in and I parted with the pair in search of something new to explore.


  1. I see your Vision R40 has the now unobtainable Lexan chainguard. Could you post dimensions for the chainguard? I'd like to recreate a chainguard for my R40. Thanks.

    1. Greetings - the superior response is to order floating teflon chain tubes, easily available from Hostel Shoppe - they work perfectly on my Vision R40 LWB...

  2. A straightener fork would move the front wheel back enough to the cranks wouldn't hit the 26 inch tire. If you do it just right you can bend the old fork straighter.

  3. @johncd Sorry, I no longer have the R40. I sold it midway through the winter so can't help you out with the dimensions. It definitely was an odd shaped chainguard and had the downside of snagging the unsecured pant leg if not a bit cautious. Best I can do now is link you to the best photo I have of the chainguard and you can get an idea of the dimensions/shape from there: http://www.flickr.com/photos/49741739@N08/5667088970/

  4. @Tony That's a great idea. The overlap was so pronounced, though, that I'm not sure that even a straight fork would have allowed enough clearance for that wheel/tire combination. It may have also required some type of lower spacer to further raise the crank away from the dropouts. (I do like the idea of manual fork straightening as it was a steel fork. Anytime I get to make "upgrades" with a big hammer is a good deal.)

  5. Thank you!..for the info on the 16 to 20 inch wheel swap.
    Today I purchased a used R 40, my first "real" recumbent (a ReBike a decade ago) it seems to be a well constructed, well balanced machine so I bought it despite it needing some work to be roadworthy again.
    One of my first thoughts was concerning the swapping of the 16 inch fork/wheel with a 20 inch ensemble.
    Looks feasible by what I have read here (cautions well understood) so I will probably do that soon.
    I am 5ft 11 and being able to extend the frame "boom"? at the front of the bike near the crank makes all the difference. Is it true that the "Small" frame featured the 16 in wheel and the "Standard" frame came equipped with a 20 inch wheel? If so, is there a difference in those respective frames or are they the same frame with 2 different fork/wheel set ups?
    Oh, almost forgot, there is something missing in the lower stem pivot area so the PO used a toe strap to lasso/restrict the stem/bars from rotating too far forward, can the missing piece be purchased or do I need to fabricate something? I will try to load a photo of this soon.
    Thanks in advance!
    Phil C.

    1. @Phil - Congrats on the 'bent purchase! I've really had a lot of fun trying out various recumbents of various configurations and I'm sure you'll have a good time on the R40. Looking at the various iterations of the R40 I've found online, the wheel sizes definitely had some variability. I found quite a few that were spec'd with a 20" front wheel rather than the 16", and I'm guessing your frame size correlation between small/standard is accurate (I believe my two were both small frames, though there were no markings indicating such). I can't speak to any additional differences between the two frame sizes as I haven't had a chance to compare them. Does the boom extend far enough with your R40 to allow adequate leg extension? If anything I'd think you'd have an advantage with an extended boom as it would increase pedal/tire clearance and reduce heel strike probability. I was able to source a 20" fork from my LBS fairly inexpensively, but you may be able to find a used one directly from an R40 on some of the forums (bentrideronline, etc).
      As for your stem/pivot issue, both of my R40's had telescoping rubber stopper-headed bolts to adjust for proper handlebar positioning, but neither had any retention device to prevent the bar from pivoting forward (away from the rider). I've had a few 'bents with pivoting stems (Bacchetta Strada, RANS V2, Lightning P-38), and only the Lighting had any kind of mechanism to "lock" the stem in place for riding. The others simply relied on the natural "pull" exerted on the bars from the rider/gravity to keep them from pivoting forward while riding. With the R40's, this was a nice feature for transportability as I could remove the seat and the handlebar could fold up against the boom to make for much easier entry into shorter SUV's and such. If it seems something is missing, I'd definitely be interested to see a photo of the stem/pivot area to see if it's a different configuration than mine. Sourcing new parts is tricky because of the now-defunct company, but some of the recumbent shops (like bicycleman.com) may still have access to some of them. Happy riding!