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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 09/13/2012 :  01:30:52  Show Profile  Reply with Quote
As said before I've been puzzled about MBB suitability for longer events and in rolling hills courses.

While thinking the topic I recalled from memory having started Cruzbike conversion kind of project of turning normal MTB to MBB which I called quits after receiving M5 lowracer. And found that frame's cut out pieces.


This is the target...


And this is how pieces might organize around MetaPhysic geometry around ergonomics. Wheelbase is same, seat is 10cm lower and I'm going to use same hardshell seat.


Here are donor bike's frame components re-organized, with lower seat support.


And frame part is complete. Plenty of work to get it aligned correctly as aluminium does soften while warm after welding and bending some. Wheels are prefectly in line here as is frame.

Here I was compelled in building front triangle fixed for my dimensions. But as got nice idea from local bent forum to use Fauber BB adapter for BSA which might help in making pivoting BB I decided to proceed with it.

I was also lacking compatible road bike's 1-1/8" threaded fork so purchased it together with adapter.


Here is my pivoting BB ready. I didn't like building Vendetta's pivoting system which is based on clamping chainstays to external BB bearing shells. Now I can use any BSA BB my liking and avoid chainring clearance issues too.


Details of my oversized boom and stem clamping system. Needs some more milling to get true adjustability but it's very sturdy construction and in budget.


Modified this heavy but otherwise nice steel fork by spreading it using wide axles to 132.5mm to fit both modern road and MTB hubs. Then aligned dropouts and cut & re-welded DS side to clear chain with 11-12t cassettes.


Here is front triangle ready. With both derailleurs, boom is bent to clear FD and put handlebars lower. I'm using SRAM direct mount FD here, otherwise all other components are Campy Record stuff from my Tri-TT donor.


In this shape did 1st test rides in darkness of the night without brakes or shifters. Interesting ride but it works.

Mounted Campy brake handles and commuted to work next morning, all combined 31 km worth of testing with fixed 34-17 gear. This thing really wants to go uphills !

Mavic TT bars need to be modified for better ergonomics and handling. And to fit bar-end adapters for Campy Doppler shifters.


Here are Mavic TT and aero bars cut and welded together. Much better clearance for legs and palms position. Thanks for AA about his TT-Vendetta setup which I used as good example to get mine right.

Here are weight details:

  • Plain frame: 1.95 kg

  • "Framekit" : 5.5 kg including plain frame, front triangle, carbin&kevlar seat, headset

  • Whole bike: 11.55 kg with my heaviest wheelset.



Target was to use exactly same wheelsets as in MetaPhysic, and same weight, for true comparison reasons. That goal was met with ease.

When I get shifters installed, or done bar-end adapters, I'll start using this only for my legs. Then I'll gather data measeured by Garmin Edge 500 for comparing how much different MBB is over different type of legs, like 10 km TT, 40k / hour, metric century training legs etc.

First impressions do confirm other's observations: very stiff frame, lightweight overall construction, good ergonomics.

Stiffness is like comparing commuting bike to DF race bike. With hardshell seat ergonomics as good as my MetaPhysic. Learning riding was not that hard, with improved handlebar I'm confident enough to go public roads.

Cheers,
-Mika

MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010

warren
human power expert

USA
6643 Posts

Posted - 09/13/2012 :  09:33:43  Show Profile  Visit warren's Homepage  Reply with Quote
Looks great Mika! Nice work.
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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 09/13/2012 :  22:26:25  Show Profile  Reply with Quote
quote:
Originally posted by warren

Looks great Mika! Nice work.



Thanks Warren. It'll get paint when confident no more welding is needed. Likely welding small diameter al tubing to keep cables in place, when handlebar & brake handles & shifters are "stabilized".

When convenient will strip donor's paint for little better looks.

Now it has gears as finished diy bar-end adapters made from 10mm and 5mm thick aluminium slap:





Shifters are, of course, Campy Dopplers. Seems to work great with 9-speed SRAM chain/cassette/crankset but Campy Record RD likely needs cage extension to support 50t/34t chainrings with 11-23 cassette.

Today is 1st training leg on V. Better pack multi-tool and spare tires to be safe, and have mobile phone with me.

Cheers,
-Mika

Diy Vendetta @ 2012, MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010

Edited by - mhelander on 09/13/2012 23:37:40
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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 12/19/2012 :  23:54:03  Show Profile  Reply with Quote
Little bit of update here. Rode about 600 km total up to mid-October when it was just too slippery to ride FWD bent on slicks.

No real technical issues and little tuning of riding ergonomics along the way. Installed Campy Veloce dual-pivot caliber brakes and fixed RD to support better wider range of installed compact double.

Bent looks like that:



After taking this picture did one last leg prior to winter, then stripped wheelset and seat and it's hanging now waiting for summer. It'll get paint before spring time.

As it took about 200-300 km to learn how to ride this MBB FWD bent efficiently I'm afraid there's another learning curve ahead when spring arrives. Because of this I've purchased Tacx training rollers and plan is to use it to maintain learned skills over snowy winter period.

Cheers,
-Mika

Diy bents: Full-suspended off-roader @ 2012, Vendetta clone @ 2012
Commerials: MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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DamjanZ
recumbent enthusiast

Slovenia
282 Posts

Posted - 12/20/2012 :  02:47:00  Show Profile  Visit DamjanZ's Homepage  Reply with Quote
Nice work! Maybe as it looks, the bottom bracket is not stiff enough for serious climbing. If it bends or moves, consider to reinforce it.
Good luck!

Damjan

"Rowing forwards is possible, but hard."
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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 12/20/2012 :  03:06:54  Show Profile  Reply with Quote
quote:
Originally posted by DamjanZ

Nice work! Maybe as it looks, the bottom bracket is not stiff enough for serious climbing. If it bends or moves, consider to reinforce it.
Good luck!


Thanks Damjan.

I'm sorry to say but my BB construction is way stiffer than in original Vendetta. It has steel "Fauber" adapter for BSA BB inside. If anything breaks it's a boom tube, not BB.

I've already pushed couple of full-power TT's on it and it's stiff like no other (RWD fixed boom) bent I've ridden to date. To test does it stay together and how it compares to my other stiff bent, MetaPhysic.

But what I'm saying about power production when compared to Auré and others. I'm just doing 10 km rolling road TT's in high 13 minutes, hour track race in about 40 and 200 km in tad over 6 hours (both in heavy wind, over car test track). Still I have some friction issues when pushing this in TT speeds to uphills despite keeping cadence high (90+ in MBB, 95+ in FWD bents).

Other parts of frame might not be as stiff as CruzBike's, but hey this is homebuilt in very low budget (sub-100 € for rideable form, sub-150 as in picture).

Cheers,
-Mika

Diy bents: Full-suspended off-roader @ 2012, Vendetta clone @ 2012
Commerials: MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010

Edited by - mhelander on 12/20/2012 03:11:24
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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 07/03/2013 :  15:24:54  Show Profile  Reply with Quote
As a proof that BB pivoting is stiff, I broke boom from next welding seam up from BB. While riding on bike path easy recovery leg next day after 6 hour offroad race.

Had to walk little over mile to pickup point in road shoes and cleats. So moved seat and pedals to lowracer and little over month later had time & motivation to fix this.

First I had to fix obvious bugs in my construction. One contributing to premature weld fracturing was my QR which didn't squeeze chainstays and fork properly to Hope Pro III axle. Then had to bend chainstays and BB to proper orientation, then using angle grinder did deep V to seam area and welded it back together.

I remembered that late -80's vintage Campy Record RD had some issues with shifting and keeping chain adequately tight with 11-21 9sp cassette and 50t/34t compact double. With some grinding paste, use of sand paper etc got B-pivot to function well enough that when RD is mounted little loose using thread locking compound it works as well as it's designed originally. Then aligned RD as it needs to be in upright chainline which FWD-MBB shares.

So, today after three rainy days took it to my 55 km reference race course. Started very easily as this was my 3rd ride year to date on it and I'm in need to recall my RWD-MBB riding skills. After some wobbling I got pedaling even enough with comfortable cadence and shifted to big ring.

Oh boy this is so easy to ride inclines. I executed different variation of my climbing strategies from upright riding times and dang this bent. In mostly dry tarmac I'm having driving wheel slippage and able to approach 2-4 % inclines in 37 kph speeds and maintain that over those not so long climbs.

I rode rest of the course in big ring. That's first time ever I've done that in course, racing or training. Still cadence in 90+ range which works for my puny legs.

I needed that hard ride. As did the machine. I want it to break, if it does, before next longer leg or any TT or race.

Cheers,
-Mika

Diy bents: Full-suspended off-roader @ 2012, Vendetta clone @ 2012
Commerials: MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 08/15/2013 :  00:09:52  Show Profile  Reply with Quote
Some updates about this bent too.

I fractured frame again, from next seam up, when finalizing local "SankiTT" 10 km course's incline in full steam. This time was able to ride it back home for repairing. Good that it broke because soon after we had Finnish recumbent nationals where I targeted to ride this...

Week before nationals did last little more serious leg on 55 km "race" course. With steam to spare I did 1h 33min time which would be winning time @ 2011... looking good, really good.

So in nationals rode this with 60mm deep rims, Conti Podium 19mm tubulars. Got 53.9 kph @ 200m speed traps, 5th unfaired. Then won hour race with not so stellar 40.03 km distance, targeted to 50 km but some serious competition would've helped much.

12h race target was 400 km, exceeded 200 km @ 5h 50min and looking & feeling good. I lost focus and speed between hours 6-8 but got it back and rode consistent lap times up to 11h. Then I was short 44 km from my target so decided to cool down remaining hour and my result was about 375 km after 11h 45min riding, moving time 11h 6min.

Definitely FWD-MBB seems to be as good as dual disc (M5 CrMo) lowracer for me... And, yesterday rode my best 10 km TT time ever, 13min 8sec. Previous record was 13:18, ridden @ mid-90's on tricked Rossing Tri-TT. As I seem to be peaking my performance I'll attack other 10 km TT courses and records, including local "official" SankiTT 10m km course with U-turn.

My best 10 km TT time on bent before yesterday was 13:53 on lowracer with dual discs @ 2012.

Cheers,
-Mika

Diy bents: Full-suspended off-roader @ 2012, Vendetta clone @ 2012
Commerials: MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010

Edited by - mhelander on 08/15/2013 00:12:35
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warren
human power expert

USA
6643 Posts

Posted - 08/15/2013 :  06:16:33  Show Profile  Visit warren's Homepage  Reply with Quote
Wow, great performances Mika, and good job of getting the Vendetta clone bulletproofed before the big Fin Nationals!
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Speedbiker
human power expert

USA
3835 Posts

Posted - 08/15/2013 :  13:55:11  Show Profile  Reply with Quote
Like many of us, Mika just keeps getting faster! Where will it end? Most of the time I look at my speedo in amazement....
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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 08/15/2013 :  14:24:19  Show Profile  Reply with Quote
So true Thom. I started my TT pull moderately but after seeing 40+ kph speeds in early inclines started to realize it's gonna be flying time. My HR average was below 170 so plenty of steam left... to be pushed even harder in upcoming TT events.

Thanks Warren, seems I got it built now solid enough for painting it next. Likely after conditions are too slippery for FWD riding.

Cheers,
-Mika

Diy bents: Full-suspended off-roader @ 2012, Vendetta clone @ 2012
Commerials: MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 09/23/2013 :  02:01:02  Show Profile  Reply with Quote
I'm still unlucky building anything that lasts from aluminium.

Little while ago I broke boom weld again, had to ride 26 km with fractured seam and last 6 when it broke totally loose. Too lazy to fix it...

Until Saturday removed seat to return it to MetaPhysic. Noticed that there's fracture near weld below seat. No wonder it felt flexy before boom broke...

I'll re-weld those and ride it on training rollers over winter season to maintain my MBB skills. And use it for jig building, maybe it's time to construct something from better materials for next summer.

Cheers,
-Mika

Diy bents: Full-suspended off-roader @ 2012, Vendetta clone @ 2012
Commerials: MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 03/02/2014 :  23:36:17  Show Profile  Reply with Quote
Little update here... Here are some pictures of this bent while had enough time at hands to fix broken boom weld and discovered frame fracture:



Diy-V without seat and wheelset, straight from winter storage.



Front boom fracture, reason to stop riding this soon after doing my best ever 10 km TT record of 13:08.





These two pictures are taken just behind seat front mount. I was totally amazed that there was fracture as forces causing it are generated from upper seat mount. Also carbon damping plate between that mount and seat was totally done.

And at last, here is picture of it after my first ever test ride on snowy bike path:



Equipped with newly build wheelset around 2 years old DT-Swiss R520 rims, using NovaTec superlight road hubs and Aero424 flattened spokes in radial+radial/2x setup.

Those Schwalbe Marathon 25-622 Green Guard tires are about good enough for riding on sanded roads and dry hard snowy surfaces. Fattest fitting tires in both ends.

Cheers,
-Mika

Diy bents: Full-suspended off-roader @ 2012, Vendetta clone @ 2012
Commerials: MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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warren
human power expert

USA
6643 Posts

Posted - 03/03/2014 :  05:51:34  Show Profile  Visit warren's Homepage  Reply with Quote
Looks like in both cases the crack was next to a weld, so likely the aluminum got very hot there, which weakens the metal.

From wikipedia: http://en.wikipedia.org/wiki/Aluminium_alloy

Heat sensitivity considerations[edit]
Often, the metal's sensitivity to heat must also be considered. Even a relatively routine workshop procedure involving heating is complicated by the fact that aluminium, unlike steel, will melt without first glowing red. Forming operations where a blow torch is used can reverse or remove heat treating, therefore is not advised what so ever. No visual signs reveal how the material is internally damaged. Much like welding heat treated, high strength link chain, all strength is now lost by heat of the torch. The chain is dangerous and must be discarded.
Aluminium also is subject to internal stresses and strains when it is overheated; the tendency of the metal to creep under these stresses tends to result in delayed distortions. For example, the warping or cracking of overheated aluminium automobile cylinder heads is commonly observed, sometimes years later, as is the tendency of improperly welded aluminium bicycle frames to gradually twist out of alignment from the stresses of the welding process. Thus, the aerospace industry avoids heat altogether by joining parts with rivets of like metal composition, other fasteners, or adhesives.
Stresses in overheated aluminium can be relieved by heat-treating the parts in an oven and gradually cooling itin effect annealing the stresses. Yet these parts may still become distorted, so that heat-treating of welded bicycle frames, for instance, can result in a significant fraction becoming misaligned. If the misalignment is not too severe, the cooled parts may be bent into alignment. Of course, if the frame is properly designed for rigidity (see above), that bending will require enormous force.
Aluminium's intolerance to high temperatures has not precluded its use in rocketry; even for use in constructing combustion chambers where gases can reach 3500 K. The Agena upper stage engine used a regeneratively cooled aluminium design for some parts of the nozzle, including the thermally critical throat region; in fact the extremely high thermal conductivity of aluminium prevented the throat from reaching the melting point even under massive heat flux, resulting in a reliable lightweight component.


To fix this the entire frame can be heat treated, or the frame can just be left to sit for a year or so and gradually the aluminum regains it's strength.

-Warren.
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mhelander
recumbent enthusiast

Finland
384 Posts

Posted - 03/03/2014 :  07:26:22  Show Profile  Reply with Quote
So true and reason for my failures. No available post weld heating so this time it'll post cure over time, some months this time.

Next frame will likely be built from 1-3/4" 0.068 wall CrMo and have similar rear suspension with air shock than diy-offroader. Little longer wheelbase. Rigid carbon front triangle with JM inspired slotted and adjustable BB. More reclined seat, focus on more aero and stiffer construction.

Cheers,
-Mika

Diy bents: Full-suspended off-roader @ 2012, Vendetta clone @ 2012
Commerials: MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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