Increase rear tire clearance on V20c

[Henri]

While I want the aerodynamic body position of the Vendetta, I also want comfort for me and my luggage and ride bad roads and am slow enough to not suffer too much from the aero drag of wider tires.
The rear has so much clearance for width, but is maxed out in hight at 28-622 to 32-622. I could get a smaller rim diameter to fit a wider tire, but I want both rims equal and sizing down the front would not bring any advantage, as the front is sadly very narrow.
What limits hight are the cross beams, where rim brakes could be mounted. Are these beams important for strength of the rear? I could easily remove them and have room for about 40mm tires, i guess; the luggage in my hard tail box* would love that. As the frame is made from aluminium, I can't just have someone weld a new U-shaped piece in it's place. I could probably have someone build a brace that clamps and/or glues to the struts or mold it out of carbon fiber. - I could also just remove one half of the square block where the brake would be mounted, this would at least give me a few more millimeters. Or maybe hammer the strut out of the way a bit? XD

*) Report and pictures of the tail box will come later.

 

[ratz]

You'd be better off fabricating a offset bracket to lower the rear drop out; such that a 650b yeilds the same height and trail as the a 700c on the front; That's that's how the tilting trike prototype works. But in the end you just building an S40.

That said don't cut the frame bike frame stability isn't something to screw with (you don't want to build a sigma) that brace is carrying a lot of lateral load and twisting torque when you lay into turns. Last time I saw a photo of one breaking in that spot the frame just folded over. ... Get a wider tire and put a 32 on it tubeless and run low pressure.

 

[Henri]

fabricating a offset bracket

An offset bracket I would rather use to put the wheel further back. That would give me the clearance for 40-622 and correct the weight distribution a bit, because I have my luggage far back.

frame stability isn't something to screw with

That's why I ask if that part is important Could have been that it is only for mounting the brakes. (A boy can dream…)

in the end you just building an S40

I would have bought the S40, had I not wanted the flat body position of the V20(c).

Get a wider tire and put a 32 on it tubeless and run low pressure.

That would be the plan otherwise. There is just so much wasted potential in the width, that I have to check for possibilities first. I don't consider 32mm as being wide. (My other recumbent bikes have tire widths from 44mm to 127mm. - And the 44mm will be going to 50mm or more as soon as I get to it. )

 

[cruzKurt]

Why not 650b front and rear? Is there a problem with that?

 

[CruzRider]

Some other ideas
1. I see there is a S30 for sale
Flatter position and more tire clearance.
2. Try Berd Spokes. They make a 32c feel like a 40c with the right (compliant) rim. Fantastic ride quality.

 

[ratz]

An offset bracket I would rather use to put the wheel further back. That would give me the clearance for 40-622 and correct the weight distribution a bit, because I have my luggage far back.

Good Point; that's been done before. I don't recall who, probably Hamish

I would have bought the S40, had I not wanted the flat body position of the V20(c).

There's a nice s30 for sales..... lol with a bigger small tire problem ...
.

That would be the plan otherwise. There is just so much wasted potential in the width, that I have to check for possibilities first. I don't consider 32mm as being wide. (My other recumbent bikes have tire widths from 44mm to 127mm. - And the 44mm will be going to 50mm or more as soon as I get to it. )

A Zockra with 42mm

Rear offset is probably the way to go but you get some impact on the trail relative to the fork angle might get a bit "chopper like on the turning but if you only go make enough to clear the frame, it's probably not going to be that noticeable under 25 mph. @Robert Holler knows this stuff way better than I do. He'll probably tell us how good or bad an idea it is. Chances are he's tried it just to find out.

 

[Henri]

I don't recall who

I am pretty sure, I have seen a video on the Cruzbike YouTube channel about testing longer wheelbase on V20. Or some other output from Cruzbike themselves.

A Zockra with 42mm

One of those sexy aero-carbon MBB lowracers? Yeah, if available, that would be an option. - Only with same wheelsize front and rear, though.

Why not 650b front and rear?

- better tire choice in 28"
- already have expensive 28" wheels
- larger diameter rolls smoother ad faster, so I would lose in the front part of what I gain in the back. If the front also fit a wider tire in 27.5", I'd done it already, but sizing down both to widen just one, doesn't quite convince me. Not totally out ofnthe question, though. Maybe as part of a changeable wheelset strategy.

 

[ratz]

One of those sexy aero-carbon MBB lowracers? Yeah, if available, that would be an option. - Only with same wheelsize front and rear, though.

Yeah sorry he got out of bikes before he could ship any of these. Would have been fun to race against a v20. Alas same wheel size problem. Probably worse.

 

[Henri]

I think the lower the rider sits between the wheels, the more frontal area overlaps, the less tire width is aerodynamically disadvantageous. (Same for the fork.)
But that's a sidetrack to this story.

 

[Mathew Fy]

I saw a FB post about how to get more front wheel clearance. Ingenious!

 

[Henri]

Ah, that's something. Do you know what tools were used?

 

[Mathew Fy]

An offset bracket I would rather use to put the wheel further back.

Maybe the Ninja V18 adapters

6-12-24 World TT Championships, Report from Borrego Springs: brief

Here is a bullet list, with photos, of some highlights of the event. 1) Cruzbike racers Jason Perez (24H), Kevin Gambill (12H), and (moi) Jim Parker (6H) each set the overall recumbent record in their events. Here are all the new and historical 6-12-24 Hour recumbent results: 2) Big thanks...

forum.cruzbike.com

 

[Henri]

Maybe the Ninja V18 adapters

6-12-24 World TT Championships, Report from Borrego Springs: brief

Here is a bullet list, with photos, of some highlights of the event. 1) Cruzbike racers Jason Perez (24H), Kevin Gambill (12H), and (moi) Jim Parker (6H) each set the overall recumbent record in their events. Here are all the new and historical 6-12-24 Hour recumbent results: 2) Big thanks...

forum.cruzbike.com

Ah, that's probably what I have seen (but probably not in that post). These drop the frame, though. That would not work with my tail box, that is sitting very close to the wheel already. :/

 

[Robert Holler]

I saw a FB post about how to get more front wheel clearance. Ingenious!
View attachment 15540

This makes me hurt inside.

 

[Henri]

I was just on Instagram and felt so inspired by the posts with hashtag tightclearancetuesday.

#tightclearancetuesday on Instagram | Hashtags

965 posts - Discover photos and videos that include hashtag "tightclearancetuesday"

www.instagram.com

BTW interesting that Robert posts in this thread and says nothing about the possibility of modifying those brake bridges. Probably nothing can be interpreted into that loud silence. ;-P XD