S40 questions

[Robert Holler]

Going back to the brake question... no canti or V brake mounts on the S40. There is a "brake"bridge that looks like you could use a caliper brake, but no standard one will work. You can use a long reach caliper, but those are not nearly as good as anything really - so disc brakes it is. When using road levers you have to make sure the disc calipers will work with that type of lever.... I recommend TRP Spyre calipers on the S40.

 

[ak-tux]

99.999999....% who buy bicycles are not competition racers. It's important to promote recumbent bikes among the general public for the purposes of human powered transportation, leisure, and exercises for health, etc.

There is too much space between the main frame of S40 and the wheels. I think S40 can be improved by making the main frame lower, moving the seat forward, and shorten the chain stay. Use modern high strength steel or titanium to reduce the weight. 36 degree back inclination would be better. I think 40 degree is a bit too much, and it was the reason that I mentioned T50. The steering system is very strange to me. Use push/pull action on the handlebar to sway the far-away BB. I would think the torque should be applied to the steerer tube. I'll wait till September 18 to see what changes have been made in V20, perhaps purchase a V20 instead.

Your design proposal above (460mm seat height at 34 deg angle) is nice, I must say. However, from my own experience, a continuous or direct connection from the handlebar to the BB is the best for this FWD MBB bicycle(the V and the S have a direct connection ). This is because strong pedalling forces create a bending moment on the vertical steerer tube if the handlebars are attached to the steerer separately(as in the T50 and the Q). Fitting the above design to a wide range of rider sizes will be a challenge becuase it requires a large range of possible stem length sizes or different frame sizes altogether.

I'am sure Cruzbike made alot of considerations for the S40 before they released it. That is, road visibility, the sitting height of the rider, weight balance between the front and rear wheel, strength of the frame for touring with load, tire clearance, fit adjust-ability, cost of production e.t.c . Most of the S40 owners on this forum so far seem to really like the ride quality. Therefore there must be something right about it's design.

It would be best if one could test these cruzbike models and decide which seat angle and height is the most efficient for a specific purpose. If you are a home builder or good at DIY projects you could experiment.

Which is your current recumbent?

 

[dtseng]

ak-tux
Thank you for your precious input. I don't have any experience with recumbent. I've been riding DF road bike for over 30 years and currently own 7 bikes. I participate in this forum to gain knowledge about FWD/MBB before jumping in to buy a cruzbike. Most of my road bikes weigh 8 + - 0.5 Kg. Now if I change to a bike weighing 5 to 6 Kg heavier with a much longer chain, I would definitely feel a big drag on me. I have some doubt about the price of this penalty is enough to pay for the reduced saddle pain. Therefore, I hope the total weight and the chain length have to come down. OK, a recumbent has a big seat which contributes to 1.5 Kg, the bike should weigh no more than 10 Kg.

Cruzbike has put in a great deal of effort trying to promote FWD/MBB recumbents, first the conversion kits and now T50. Put competition aside, I don't know why it is still not accepted by the general public. The city where I live has one million population, but has only one cruzbike (Q559). LBS here sells recumbent trikes, which are gaining popularity among the older folks.

 

[ak-tux]

ak-tux
Thank you for your precious input. I don't have any experience with recumbent. I've been riding DF road bike for over 30 years and currently own 7 bikes. I participate in this forum to gain knowledge about FWD/MBB before jumping in to buy a cruzbike. Most of my road bikes weigh 8 + - 0.5 Kg. Now if I change to a bike weighing 5 to 6 Kg heavier with a much longer chain, I would definitely feel a big drag on me. I have some doubt about the price of this penalty is enough to pay for the reduced saddle pain. Therefore, I hope the total weight and the chain length have to come down. OK, a recumbent has a big seat which contributes to 1.5 Kg, the bike should weigh no more than 10 Kg.

Cruzbike has put in a great deal of effort trying to promote FWD/MBB recumbents, first the conversion kits and now T50. Put competition aside, I don't know why it is still not accepted by the general public. The city where I live has one million population, but has only one cruzbike (Q559). LBS here sells recumbent trikes, which are gaining popularity among the older folks.
View attachment 5436

Now, you have basically drawn the last iteration of a Silvio S30 ! The only difference is probably the seat height for the S30 was about 40mm higher and the seat angle was 33 deg! The only advice I'd give is that you increase the wheel base from 1080mm to 1180mm and you will get more plush or vertical compliance and better traction.

If cost is an issue, I would strongly advice that you try and weld together something from old bike frames and parts. It will give you a chance to feel the MBB format without spending too much on something you may not like. Better still, get a T50 frameset only and modify the seat stays to achieve a 35deg seat angle. Then modify the steerer and boom to get a straight and direct connection to the BB. It's been done and documented in this forum by one @Emeljay here http://cruzbike.com/forum/threads/qx100-steering-mod.10853/.

However, for DIY, you may have to change your design a little to make it easier to use straight tubes as the above design lends itself to miter joints or alternatively some nice hydro-formed curved tubes like on the V and the Silvio which are factory made.



On the issue of weight, I can assure you that, unless you are racing hilly route or doing a criterium, where acceleration and climbing is important, you will generally not notice the weight increase that much once you get going on the bike. On a good MBB recumbent 11Kg may feel like a 9 Kg road bike in terms of response. To Build a recumbent 8 or 9 Kg will require some very careful design and choice of materials. Carbon will probably be inevitable.

That said, does this fit your design?

or this?

This was the last iteration of the Silvio S30. Unfortunately no longer in production. Its hard to get unless someone in this forum is willing to sell a used one to you. But I highly doubt it!

 

[Suz]

99.999999....% who buy bicycles are not competition racers. It's important to promote recumbent bikes among the general public for the purposes of human powered transportation, leisure, and exercises for health, etc.

There is too much space between the main frame of S40 and the wheels. I think S40 can be improved by making the main frame lower, moving the seat forward, and shorten the chain stay. Use modern high strength steel or titanium to reduce the weight. 36 degree back inclination would be better. I think 40 degree is a bit too much, and it was the reason that I mentioned T50. The steering system is very strange to me. Use push/pull action on the handlebar to sway the far-away BB. I would think the torque should be applied to the steerer tube. I'll wait till September 18 to see what changes have been made in V20, perhaps purchase a V20 instead.

I am curious as well why you wouldn't just buy a used S30? Seems you don't care for the S40. Please enlighten us.

 

[Don1]

i have noticed in diy... that the more higher tech you go unfortuneately the tollerencies go down
ie going from mechanical disc to hydo disc. if your not prepared to be particular with jigs and engineering. i'm over it. i'm off to get me a real cruzbike they look amazing and go awesome... nothing a bank loan wont fix

 

[Robert Holler]

I know where there is a basically new S30. The last one. Literally.

 

[Doug Kline]

I know where there is a basically new S30. The last one. Literally.

The new Cruzbike museum?

 

[Kenneth]

yes i have upgraded a silvio and a vendetta with hardshell seats and it is a good option ! So yeai may do it on the s40 but want see how the stock seat does with the ventitsit before i spend $$$$ on a new seat!

hello, how did you end up liking the ventitsit pad made for the S40? did it fit better than the stock cushion,my option of it matches your earlier post about it. I'm considering getting one but only if its wider the the stock.
regards
Kenneth

 

[Vulcanelli]

This discussion has me trying to understand some of the considerations of recumbent design. I understand on of the appeals of front wheel drive is using a ridged triangle to connect the bottom bracket, crank and steering stem.

Another advantage of a recumbent is lower wind resistance. Thus, lower would seem better, however the lower you are the less you can see. No doubt Cruzbike has good reasons for their designs although I have no idea what they are and maybe that is a good thing. Here is my thinking.

Lowering the power triangle (modified) would lower wind resistance and increase visibility while maintaining the same pedal distance. The horizontal boom could be forked to straddle the front wheel. I know it looks a little wonky but I am really wondering about the practicality of this kind of setup.

 

[Jeremy S]

For one thing, you're not taking into account that arms and legs work as a unit on MBB. This is the reason for the near-unbroken single tube connection from the handlebars to the bottom bracket on the performance models. With your revised design, under power, riders are going to twist the handlebars right out of place. Another consideration is adjustability, I'm not sure there's much room to adjust pedal reach on your render. Cable routing to the FD looks tough. Finally I'm not sure how this would help with either visibility or aero, since the handlebars and bottom bracket are typically what get in the way of visibility (and they haven't moved), and the frontal area/shape of the bike is still the same, you're just tweaking the Cd in a way I'm not sure would help. Sorry to be a negative nelly.

 

[ak-tux]

...

Lowering the power triangle (modified) would lower wind resistance and increase visibility while maintaining the same pedal distance. The horizontal boom could be forked to straddle the front wheel. I know it looks a little wonky but I am really wondering about the practicality of this kind of setup.


View attachment 6223

There would be a lot of flex at A at climbing because strong pedalling forces need to be countered by the arms. It also puts a lot more stress on the steerer. The Silvio/Vendetta boom is in line with pedalling forces. It's the stiffest configuration.

 

[Layne]

hello, how did you end up liking the ventitsit pad made for the S40? did it fit better than the stock cushion,my option of it matches your earlier post about it. I'm considering getting one but only if its wider the the stock.
regards
Kenneth

The s40 vintitsit is much better than the stock pad ! the fit is very good !

 

[Kenneth]

The s40 vintitsit is much better than the stock pad ! the fit is very good !

cool,thanks

 

[Markopolo]

This discussion has me trying to understand some of the considerations of recumbent design. I understand on of the appeals of front wheel drive is using a ridged triangle to connect the bottom bracket, crank and steering stem.

Another advantage of a recumbent is lower wind resistance. Thus, lower would seem better, however the lower you are the less you can see. No doubt Cruzbike has good reasons for their designs although I have no idea what they are and maybe that is a good thing. Here is my thinking.

Lowering the power triangle (modified) would lower wind resistance and increase visibility while maintaining the same pedal distance. The horizontal boom could be forked to straddle the front wheel. I know it looks a little wonky but I am really wondering about the practicality of this kind of setup

---------------

The headset needs to be out by the crank to nullify all the pedal torque. Let the wheel drag like on the front of a shopping cart. Attach the steer tube to the top of the fork and I guess lay the handlebars in your lap.

 

[Uphill]

The ventisit seat pad comes in a couple of flavours, standard and comfort. The comfort being an extra cm thick.

https://www.ventisit.nl/en/76x26-18-22-cm-Cruzbike-p28856169

 

[ElyDave]

Looking at Robert's comment above, has anyone built one of these with caliper brakes?

I have a donor bike with long reach dual pivot caliper brakes, which I intend to use for the initial build. They've only failed to stop me once, in the driving rain, and luckily there was a car in front of me to do that instead.

 

[Gary123]

LUCKY!

 

[ElyDave]

Lucky in that 1) no damage to bike (stem turned around a bit), wheel OK, frame OK 2) jaw not broken (always good) 3) I could ride away from it 4) the driver didn't sue for breaking their rear wiper and leaving my faceprint on their rear window.

It was all rider error I'm afraid. Crossing a roundabout, focussed on that, accelerating and missed the pedestrian on the crossing 20 yards after the roundabout. Driving rain, rim brakes, meh!

 

[Luis Rives]

I am also interested in which long reach dual pivot caliper brakes would fit on an S40. A while back I downloaded a photo from a post in the Forum showing just such a set up but I cannot recall the post. Was wondering if the Tektro R559 long reach brakes would work.