What's with the struts?

[FarHorizon]

I got to ride my new Bacchetta Corsa today for the first time. Since I've never ridden a recumbent, much less a high-racer before, I took my first spin on a grass parade ground. As it turned out, no problems - no spills. I still have to get used to steering less & leaning more, though.

After about three laps (with six or eight starts/stops just to get the hang of it), the seat collapsed backwards! Fortunately, the struts didn't get into the derailleur or spokes and no harm was done to the bike or to me. The bottoms of the struts on the Bacchetta are held onto the rear lugs with what look like 5mm bolts. Both bolts backed out & fell off. I found only one of the two, and it shows no signs of distress on the threads or shaft. The struts seem undamaged. The rear lugs on the Bacchetta, by the way, are cut with threads for the strut support bolts, and no through bolt is used, nor any nut.

I've asked my LBS to drill out the struts & lugs to accommodate 6mm through-bolts, which I asked be fitted with lock-washers and nuts. Since the frame is steel and the vector of force will be in a direction where the lug has lots of extra meat, I think this modification is OK.

Questions: Why did the 5mm bolts back out after only a mile or less of riding? They were tight when I started (the LBS tightened them before I picked up the bike while I watched!). I weigh 275#, but the steel Bacchetta should handle that OK.

Is the "bore out to 6mm" plan sound, or is there anything I've overlooked?

Thanks.

[Dchiefransom]

A bolt by itself can come loose from vibration easily. I usually get a longer bolt if necessary and put on a split ring lock nut.

[SoonerBent]

Unless you bought a left over Corsa from 2004 or before it is alumininum, not steel. I would try longer 5mm bolts with nylock nuts. And please take no offense but I've seen 3 Bachetta high racers have strut connection problems and all three riders weigh well over the 230 pound advertised limit.

SB

[Trsnrtr]

The bolts on my Aero used to come loose regularly, despite loctite. I never got around to running a bolt through and nutting it, though that would have been an obvious solution.

Just for the record, I don't weigh over 230#. :)

[FarHorizon]

Unless you bought a left over Corsa from 2004 or before it is alumininum, not steel...

My Corsa is a steel, 2004 model. I was told (by several sources) that the reason Bacchetta placed the 230# limit on the Corsas was because of the 650c Bontrager wheels. The wheels that came on the Corsa were radial-spoked, light-weight, and narrow. I replaced the original wheels with 26" MTB wheels with 1.75" multi-surface Michelin tires. The new MTB fork, wheels, & tires showed no signs of distress when I rode.

The struts, so far as I can tell, are the same struts used on other Bacchettas without any weight limit. That being the case, I believe the "weak point" in the construction is the 5mm retaining bolt that is designed to thread directly into the rear lug. I'm willing to try the 6mm through-bolt modification in hopes of eliminating the problem. Should the mod fail to achieve what I want, "plan-B" is to replace the original struts with fixed-length sections of angle iron, through-bolted at both the seat back and the frame.

[SoonerBent]

Since you aren't having trouble with the 5mm bolts breaking I don't think I would drill the holes. Just get longer bolts that would utilize the threads in the frame and then back them up with nylock nuts.

P.S. The thing I've noticed when following other Bacchettas is that larger riders and guys that really mash instead of spinning flex the struts from side to side. Especially when taking off. I can see where that would work the bolts loose.

SB

[FarHorizon]

...The thing I've noticed when following other Bacchettas is that larger riders and guys that really mash instead of spinning flex the struts from side to side. Especially when taking off. I can see where that would work the bolts loose.

Thanks, Sooner, you may be right. I mash like crazy (but only when starting from a dead stop) to gain and maintain balance. Once under way, I tend to spin more.

Another thing I noticed on my brief maiden voyage is that my feet are high up there! Since I have MTB platform pedals with spikes, they keep my feet in place OK. I can see why the guy said get clipless, though - if you aren't careful, your feet could fall off the pedals!

Finally, does anyone make a seat cover for that open-cell foam that Bacchetta uses on their seat? The coefficient of friction on that foam is so high that the bike almost sticks to my butt when I try to get up! Maybe this is a desirable design for some reason I'm not aware of?

Thanks!