rx7mark
Guru
Aluminum bike frames can't be retrofitted with S&S couplers but S&S makes aluminum specific couplers for bike frame fabricators, but they are unique to each frame.
Mark
Are there new V20s coming out?
- Thread starter Enid
- Start date
Mark
Bill Wightman
Well-Known Member
This is a very intriguing discussion. I have been a nuts and bolts mechanical engineer for 39 years now so I love this stuff. There are a few ideas for the front end of the V20 that could be incorporated with some prototyping. I do not think that performance and packing convenience are compatible goals. A one-size-fits-all bike has created performance compromises in weight and frame deflection under load that DF manufacturers have solved with (gobs of money and...) frame sizing instead (like shoes). Attached is my version of Powerpoint engineering for cleaning up the front end with conventional aluminum and steel. All I look for is lighter, faster, and more responsive. Packing/shipping is not a consideration.
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Frito Bandito
Zen MBB Master
I have been thinking about this for well over a year, and have spent countless hours researching online on how to not only lighten it but also make it as aero as I can within my limited capabilities. I don't want to break the bank doing it, so I am taking my time, but I don't mind throwing money at it if that is what gets me what I want. I have a feeling that soon I will get it sorted, I just need 1 very specific part that I can't seem to get my hands on.
3bs
whereabouts unknown
Oh how happy I am to have lit the fuse.
For me, I try and look at changes and upgrades through a manufacturers eye.
Jm demonstrates what can be done on a hand built bespoke basis. And even his stuff has room for improvement. Handbuilts with full technology available and unlimited time and money can be extraordinary, but not available to regular humans.
So I try to view any change as one that could be added to the mfg distribution process in a real business.
Keep it rolling team.
For me, I try and look at changes and upgrades through a manufacturers eye.
Jm demonstrates what can be done on a hand built bespoke basis. And even his stuff has room for improvement. Handbuilts with full technology available and unlimited time and money can be extraordinary, but not available to regular humans.
So I try to view any change as one that could be added to the mfg distribution process in a real business.
Keep it rolling team.
Frito Bandito
Zen MBB Master
In the short time I have been an active member I am amazed at what many of the members here have been able to do with their bikes. It feels like being a kid in the candy store, and while what I would like to do with mine is hardly revolutionary to probably everyone one here, it is still new to me without even considering how I always personalize my bikes. 1 of the great things about this forum is that the customizations and personalizations are appreciated, and the dissemination of advice flows freely.
Gawd I can't wait to start upgrading
Gawd I can't wait to start upgrading
Bill Wightman
Well-Known Member
This prior post idea overlooked the bending effect of tension in the chain on the forks. Here is a way to address that while improving aerodynamics of forward forks. One version does not use tension rods which may be too unusual for some even though that is what a wheel design uses.
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benphyr
Guru-me-not
I like this but not sure if I understand how these changes would save weight. Can you explain a little more so me with an engineering type mind but no education so I don’t know any if the terms?
super slim
Zen MBB Master
I think the biggest aero improvement will be seen very soon with Larry's Thor rear Pannier!!!
Bill Wightman
Well-Known Member
Warning: what follows is a true "wall of text".
It is like building a truss or suspension bridge. Over very short distances like overpasses you use straight segments and pillars, over longer segments you use segments supported by a truss work of steel members above or below, and over the longest bridges with limited ground pillars the segments are only supported long cables with vertical cables running down to the bridge segments. The longest bridge project budgets (in deeper water) cannot afford the material and labor of an inefficient design.
In the case of the triangulated DF design the design is close to perfect for stress because all power crank, weight, and upper torso loads are mostly in compression or tension in the frame segments except for some bending and twisting in the front downtube (that is why it is so big). The loads between the handlebar and the bottom bracket are well handled by the short distance and large section of the downtube on a DF. Because the other tubes in a DF frame are integral (either welded or laid up in carbon fiber overwrap) they also share the loads to a lesser extent. This integration or permanent joint assembly condition also helps make these frames featherweight. The frame is made up mostly of triangles and that is the most efficient way to move loads around.
The main problem with the front of the V20 is that the slider (which is a down tube equivalent) is very long and has two joints between the handlebars and the the bottom bracket. The long tube and joints allow steering loads from the handlebars to be absorbed by the slider and chainstay before they even get to the front wheel. The current stem attach method is not stiff and does not transmit torque to the front fork. A different approach would be to allow steering loads to go directly to the fork through the head tube with a conventional clamped stem. This way steering inputs are more subtle and directed efficiently to the wheel. The slider tube presents the problem of lost energy/torque through heat (believe it or not) because the bending of the slider and small but continuous joint motion in the length adjustments, joint at the BB, and the additional joint down at the front axle. To get rid of that problem in concept 3 there are two welded struts running from the fork crown and welded to the bottom bracket and one strut running from and welded to the middle of the BB back to the head tube stem where a high-torque bolted joint is required for assembly. These three tubes can be very minimal in section, weight, and aero drag because they take load predominantly in compression and tension, similar in size to the struts you see supporting the V20 rear wheel or struts used a DF rear wheel. These three struts are short, light, and stiff and are attached to the stiffest regions of the fork transmitting loads directly into the head tube bearings. In addition these struts are closer to and buried in the wind shadow of the BB/crankarms and rider legs than the current V20 forward structures.
With smaller stiffer forward structural components come the advantages of easier and more subtle steering, reduced form and skin drag, reduced overall bike weight (faster "green light" acceleration and hill climbing), and more power efficiency from the front assembly to the wheels. Because the loads from the chain tension go to the end of the fork, the current V20 chainstay serves to react this load but at a cost of extra drag and weight. One way to address this loading problem with minimum weight is to take the existing fork strut design and fabricate the section chord (distance from the front to the back) to be 1.75 to 2 times longer/deeper. This will add a little weight but this brings with it the advantage of a chord-to-thickness ratio in the neighborhood of 5:1 which is almost perfect especially if the right teardrop shape can be fabricated (a very aero fork) and will make it 5 to 8 time stronger in bending.
A manufacturing disadvantage of all these stiff welded joints is that front BB discreet frame sizing may be needed because of the many leg lengths out there. Also to obtain the stiffest handlebar mounts, similar tiller stem multiple size availability would be appropriate for all the multiple torso and arm length combinations. The V20 currently places your bottom in a fixed location and clamps are made available to adjust for all body parts. These multiple clamp methods allow a one-size-fits-all approach at the cost of weight, bike joint wear, and energy loss/flexibility but maybe are a necessary trade to save on cost. In any case the V20 is still the fastest bike for any given power capability, especially on the flats over long distances.
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Although @Bill Wightman's ideas are interesting, I expect they're beyond the scope of the resources Cruzbike has at their disposal. Designing a new Vendetta front end from scratch is a big ask.
In my opinion, based on no factual data whatsoever, they have a highly successful design that wouldn't take a whole lot of effort to knock off of. As others have said, redoing the front triangle in CF would take 3-5 pounds off. On my S40, the front fork weighs a lot, the boom is heavy, the bars are heavy, etc. That's where I personally would like to see Cruzbike focus their design efforts.
But hey, if they can leverage Bill's design work and come up with a lighter design that performs as well I'd be all over it!
In my opinion, based on no factual data whatsoever, they have a highly successful design that wouldn't take a whole lot of effort to knock off of. As others have said, redoing the front triangle in CF would take 3-5 pounds off. On my S40, the front fork weighs a lot, the boom is heavy, the bars are heavy, etc. That's where I personally would like to see Cruzbike focus their design efforts.
But hey, if they can leverage Bill's design work and come up with a lighter design that performs as well I'd be all over it!
super slim
Zen MBB Master
I think that the Cruzbike V20, S40 and Q45 front end that are ALL identical, even with the same max 700c tyre width.
The chain load would be 60 kg for a 25 kg pedal load on a 175 mm crank, and 36T chainring.
Cruzbike AND even DF bicycles have a direct tube connection with heavy connections at the Bottom Bracket to handle the pulsating mainly Compression loads (Chain side) and tension loads (Non chain side).
Putting this 60 kg.f load into the side of the fork that is not designed for it would require a lot of stiffening, and be heavier than the original design.
Having an extendable (ONE joint) mainly straight Steerer tube of a large diameter, and thin walls, to give a stiff straight continuous connection between the handlebars and the BB!!!
The multiple connections of the T50, old Quest, QX100, and Softrider steerer tube, allowed for a LOT of flexing when climbing, using the handle bars.
NO, as too fragile!!!!!
I think that Paco 1961 idea of a fixed length steerer tube that can be cut to size, and use a min length special stem to handle the existing 44 mm OD(OR larger!) Steerer tube, to attach the handle bars, (One joint) is great!
It would need an expanding plug with a lip to seal the steerer tube in case of an accident, and to stop wall collapse under the stem.
On my Softrider and Quest, I had keeps of problems of the steerer tube joint slipping, during hill starts, when I loaded a pedal heavily. I had to replace the quick releases, with lubricated grade 12.9 allen screws and nuts to get enough clamping load.
.
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super slim
Zen MBB Master
I think that the Cruzbike V20, S40 and Q45 front end that are ALL identical, even with the same max 700c tyre width.
The chain load would be 60 kg for a 25 kg pedal load on a 175 mm crank, and 36T chainring.
Cruzbike AND even DF bicycles have a direct tube connection with heavy connections at the Bottom Bracket to handle the pulsating mainly Compression loads (Chain side) and tension loads (Non chain side).
Putting this 60 kg.f load into the side of the fork that is not designed for it would require a lot of stiffening, and be heavier than the original design.
Having an extendable mainly straight Steerer tube of a large diameter, and thin walls, to give a stiff straight continuous connection between the handlebars and the BB!!!
The multiple connections of the T50, old Quest, QX100, and Softrider steerer tube, allowed for a LOT of flexing when climbing, using the handle bars.
Frito Bandito
Zen MBB Master
Great explanation Bill. If someone has already done that or something similar it would be great to see a pic of it.
I was wondering if cutting the rear triangle from a disc brake titanium bike, bending the round seat tube and fabricating a titanium boom to match the specs on the V20 front end, bending the chain stays to the proper width, and then replacing the original fork with a either a CF or titanium fork would result in a bit of weight savings.
I was wondering if cutting the rear triangle from a disc brake titanium bike, bending the round seat tube and fabricating a titanium boom to match the specs on the V20 front end, bending the chain stays to the proper width, and then replacing the original fork with a either a CF or titanium fork would result in a bit of weight savings.
super slim
Zen MBB Master
If you have a removable rear triangle like on the Silvio V2.0 and S30, it will fit into a 26"*26"*10" bike box.
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Definitely disagree with this.
super slim
Zen MBB Master
Every Tour Down Under Community ride/race I have gone in, with 7,000 other riders, I have seen 2 to 3 CF bikes with broken chain stays or front forks with a couple of high speed crashes!!!!
super slim
Zen MBB Master
What is the weight of the frame only kit, with CF seat+ cushion, and handle bar for the V20 and the S40, as my Silvio V2.2 with front /rear suspension + cf seat+ cushions +handle bar is 6.5 kg (14.3 lbs)
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ak-tux
Zen MBB Master
% agreed! Single oversized and stiff telescoping tube from BB to handlebar. Minimal joints. Can't get better than that! It's in line with pedalling forces.The only thing worth improving is the pivot point where the front chainstay meets the fork dropouts and derailuer hanger. It should probably be moved up by 20mm so that the derailluer hanger is either bolted to the fork or to the end of the chainstay and does not come out easily with a wheel change. It should be as easy to change the wheel as it is on a regular DF bicycle.
3bs
whereabouts unknown
okay to keep this rolling i will give you a little more of my past work. i talked to two carbon companies some time ago about doing a carbon fiber frame set and mold. this would be pre magic on the time line. after riding and taking apart studying several JM bikes, playing with zokra clone before i made it frankentrike, and riding and playing with my m bikes, and my v and my t, i had some ideas that i wanted to make into a bike, and my carbon skills are amateur at best.
i ended up with two possible directions. first was to work on the v20 to make three versions. 1. low racer; 2. trike; 3. trans portable with improvements. the second direction was to go carbon and do a whole new bike, or do a carbon bike.
since i only had my v, and no extra frameset, i figured i would do the other stuff first. looking at all i had worked on, i thought the JM hammerhead was my best test mule. so if i simplified my thinking, i wanted to take the hammerhead, a bike i consider to be brilliant and a decade ahead of its time, and still superior in principle to almost everything out there and eliminate what i consider to be its three issues and add one new feature:. 1 go from 650 c wheel set up to 700c and be able to accommodate 30's, 2. move steering back to the top of the steer tube; 3. decrease trail by making head tube angle more upright. and make a 2 piece bike that i can transport.
i worked on the transport issue, and solved that problem in concept, i thought i would be able to do this. however when i got the quotes back, the best price i got was 10,000.00 base, and that was with very limited changes and no engineering, and that was really conditioned upon them doing this as a gap project if they had any dead time,and they were totally booked working on a sailboat project that was taking up 98% of their company at the time. so i put that project on hold and went to work on other projects, such as frankentrike, and frankenvelo. JM has been a great help, as he had a little extra time. The Parkers have been very supportive of my experiments as well.
so, i picked the idea back up earlier this year, and started to do some experiments to try and get the steering where i wanted it and to change the bike back to 1x. but then i got distracted by my day job, and some erosion issues at home, so, at present it is handing in the bat cave with the drive line apart. i got a new bottom bracket shell, and the rest of my steering test pieces so that i could work my ideas about steering and how one would make a bike that could have enough adjust ability to fit a decent range of riders. of course magic has come out of the JM/CB skunkworks, and i can understand many of its elements, but it is a little too much race for me, and i think the hammerhead is prettier and perhaps even more aero, but its also more suited to my riding angle.
but, i think the solution is near. it is another cruzbike jm mishmash, this time at my hands not theirs.
the picture i have provided is an early set up of the hammerhead from May to demonstrate. for the end product, imagine that the boom tube is lower but not horizontal, and fully enclosed, with a smooth topside and slabsides following the tube diameter, with the handlebar coming out of the back of the front end at the top above the steertube, on a short adjustable tube. all cables run inside of the frame. rear brake cable will be a two piece with quick release at the separation point. handle bar connection will be standard so you can run whatever you want. i would like it to be 1x 11 or 1x12if i can get the range i like. if not it will be 2x.
a. transportability: the bike will be 5 pieces. 2 wheels, 1 seat, the back bone and the front end. the bike will divide at the head tube. it will unfasten at the top and the tube will come out. the bearing sets will stay with the backbone. the handbar will stay with the front end and detach to go sideways with cables all still attached.
b. adjustment for size of rider and seat angle: 1. sliding bottom bracket shell. 2 seat movement front and back over backbone. 3. small sleeved boom within front end attaching to handlebar.
c. trail and wheel size will reset with new frame construction.
d. storage box behind the seat
d. weight. 21.5 lbs right now as it sits in the picture, i so think it will be right about that depending on driveline and brakeset
so that is it for that project. it sits waiting for me to get it done to finalize that it all works. i will ride the final mock up for a while to sort other ideas out and then i will figure out who can do the carbon work for me. jm doesn't have the old hammerhead molds any more, but he and i work pretty well, and the hammerhead was his creation. maybe we can call the bike "H2 -oh!" (get it? fish - hammerhead, water - H2O)
keep in mind that this project is a parallel project to the v20 projects. for now i wont go into a long discussion about my work on the v20. i really need to finish testing ideas on the t50, then score another frameset or a used v to build a test mule.
oh and i have a day job.
i ended up with two possible directions. first was to work on the v20 to make three versions. 1. low racer; 2. trike; 3. trans portable with improvements. the second direction was to go carbon and do a whole new bike, or do a carbon bike.
since i only had my v, and no extra frameset, i figured i would do the other stuff first. looking at all i had worked on, i thought the JM hammerhead was my best test mule. so if i simplified my thinking, i wanted to take the hammerhead, a bike i consider to be brilliant and a decade ahead of its time, and still superior in principle to almost everything out there and eliminate what i consider to be its three issues and add one new feature:. 1 go from 650 c wheel set up to 700c and be able to accommodate 30's, 2. move steering back to the top of the steer tube; 3. decrease trail by making head tube angle more upright. and make a 2 piece bike that i can transport.
i worked on the transport issue, and solved that problem in concept, i thought i would be able to do this. however when i got the quotes back, the best price i got was 10,000.00 base, and that was with very limited changes and no engineering, and that was really conditioned upon them doing this as a gap project if they had any dead time,and they were totally booked working on a sailboat project that was taking up 98% of their company at the time. so i put that project on hold and went to work on other projects, such as frankentrike, and frankenvelo. JM has been a great help, as he had a little extra time. The Parkers have been very supportive of my experiments as well.
so, i picked the idea back up earlier this year, and started to do some experiments to try and get the steering where i wanted it and to change the bike back to 1x. but then i got distracted by my day job, and some erosion issues at home, so, at present it is handing in the bat cave with the drive line apart. i got a new bottom bracket shell, and the rest of my steering test pieces so that i could work my ideas about steering and how one would make a bike that could have enough adjust ability to fit a decent range of riders. of course magic has come out of the JM/CB skunkworks, and i can understand many of its elements, but it is a little too much race for me, and i think the hammerhead is prettier and perhaps even more aero, but its also more suited to my riding angle.
but, i think the solution is near. it is another cruzbike jm mishmash, this time at my hands not theirs.
the picture i have provided is an early set up of the hammerhead from May to demonstrate. for the end product, imagine that the boom tube is lower but not horizontal, and fully enclosed, with a smooth topside and slabsides following the tube diameter, with the handlebar coming out of the back of the front end at the top above the steertube, on a short adjustable tube. all cables run inside of the frame. rear brake cable will be a two piece with quick release at the separation point. handle bar connection will be standard so you can run whatever you want. i would like it to be 1x 11 or 1x12if i can get the range i like. if not it will be 2x.
a. transportability: the bike will be 5 pieces. 2 wheels, 1 seat, the back bone and the front end. the bike will divide at the head tube. it will unfasten at the top and the tube will come out. the bearing sets will stay with the backbone. the handbar will stay with the front end and detach to go sideways with cables all still attached.
b. adjustment for size of rider and seat angle: 1. sliding bottom bracket shell. 2 seat movement front and back over backbone. 3. small sleeved boom within front end attaching to handlebar.
c. trail and wheel size will reset with new frame construction.
d. storage box behind the seat
d. weight. 21.5 lbs right now as it sits in the picture, i so think it will be right about that depending on driveline and brakeset
so that is it for that project. it sits waiting for me to get it done to finalize that it all works. i will ride the final mock up for a while to sort other ideas out and then i will figure out who can do the carbon work for me. jm doesn't have the old hammerhead molds any more, but he and i work pretty well, and the hammerhead was his creation. maybe we can call the bike "H2 -oh!" (get it? fish - hammerhead, water - H2O)
keep in mind that this project is a parallel project to the v20 projects. for now i wont go into a long discussion about my work on the v20. i really need to finish testing ideas on the t50, then score another frameset or a used v to build a test mule.
oh and i have a day job.
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