1st build, BBSHD in a ???

[OlderGiantFan]

Knobbies are like Road-driving with Super Swampers.

I bought the bike for it's suspension only, the 2.5 knobbies will be removed and replaced with 2" (50mm) road tires. It's interesting this business of air pressures and rolling resistance, it turns out I've been wrong and running mine way too high. I've been running at the limit of the tire specs, which are basically just a legal requirement imposed on manufacturers and calculated as 50% of the pressure that will burst the tire off the rim. They have no connection to actual rider speed and comfort.

Tipped off, I went to this site and used the calculator to figure what I should be running

Tire Pressure Calculator

Finally a tire pressure calculator based on real-road rolling resistance measurements. On real roads—rather than on a steel drum in the lab—supple high-performance tires work best at considerably lower pressures than most cyclists are used to. Lower pressures roll as fast or faster, while...

www.renehersecycles.com

I dropped pressure on one bike to the recommended and went for a ride, it was much plusher, no jittering, and my average speed was essentially the same or better. That was on my 2002 26" Yukon running tires allowing 80 PSI, I was at 80, then dropped to 57. A substantial decrease. I did some research and uncovered that the Higher Pressure Meme came from university studies conducted in smooth hallways, not on real roads where even the best surface is covered in tiny bumps. So many misconceptions out there in the World, and we can tend to cling to them out of habit.

Here is one of those old studies that got it wrong.

https://www.researchgate.net/publication/233116413_Influence_of_tyre_pressure_and_vertical_load_on_coefficient_of_rolling_resistance_and_simulated_cycling_performance

 

[OlderGiantFan]

The ones I've come across usually are screwed into both bottle cage holes. Regardless if one screw only is "pretty normal," is that what you want for yours? Battery attached to the frame with only one m5 screw?

Of course not! But if the cradle can't sit over both screw holes I have little choice. I can't go drilling holes in the down tube, I'll have to secure the upper end of the cradle in some other fashion. This is the problem with the newer mtb bikes, the older bikes had a lot more room in the triangle. And older bikes with no rear shocks had no issues at all probably.

 

[OlderGiantFan]

Good plan, should be good on a FS bike ridden on the road. Personally I like 2.35" on mine.

I imagine the bigger tires with the lower pressures would make for a smoother ride on a non sprung bike, would you think?

 

[n00b]

Of course not! But if the cradle can't sit over both screw holes I have little choice. I can't go drilling holes in the down tube, I'll have to secure the upper end of the cradle in some other fashion. This is the problem with the newer mtb bikes, the older bikes had a lot more room in the triangle. And older bikes with no rear shocks had no issues at all probably.

You could tie a Clove Hitch over it to the frame with 1100 lb paracord.

 

[n00b]

I imagine the bigger tires with the lower pressures would make for a smoother ride on a non sprung bike, would you think?

That's what I'm imagining. Now all I need is a motor to spin with a throttle.
Yesterday they kinda spun.
It was OK until about 7/8 throttle then it started bogging out and loping. That ain't no good.
One can't be worrying about not giving it full throttle like that, no.
Today was total failure.
Idk wut man, I hooked it up to battery on a bike that works, and it did nothing.
Ordered a couple throttles and a controller today.
Both a TSDZ8 and and a BBS02 did the loping thing past 7/8 throttle yesterday.
That's not gonna get it. It's either the throttle or controller or both.
Could be motors like that can't take over a certain voltage. That BBS02 ripped with 48v for a little bit.
At 71v i had to back off the throttle to get it to go like yesterday was. (36v with 24v in series)
And Varstrom copied the BBS02 and used a rotor like BBS03.
So we'll see what happens.

 

[n00b]

Of course not! But if the cradle can't sit over both screw holes I have little choice. I can't go drilling holes in the down tube, I'll have to secure the upper end of the cradle in some other fashion. This is the problem with the newer mtb bikes, the older bikes had a lot more room in the triangle. And older bikes with no rear shocks had no issues at all probably.

Yes you can.
Secure your battery!
What harm would a couple of 1/8" holes do?
Do you think it would significantly weaken the frame?
I don't.

 

[Apartunis]

Yes you can.
Secure your battery!
What harm would a couple of 1/8" holes do?
Do you think it would significantly weaken the frame?
I don't.

If you put a hole, notch, groove or indentation in a structural tube at a point where stress is concentrated, you can easily start a crack at that location. A bicycle down tube has elevated stress near both ends. If it is thinner walled in the middle section, then the thinner material has higher stress because it is thinner.

I have seen unmodified non electric bikes that cracked at rivet holes used to mount cable stops. There is not a great surplus of structural material in most bike frames. It is better to clamp around the frame tubes than to drill into them.

 

[OlderGiantFan]

If you put a hole, notch, groove or indentation in a structural tube at a point where stress is concentrated, you can easily start a crack at that location. A bicycle down tube has elevated stress near both ends. If it is thinner walled in the middle section, then the thinner material has higher stress because it is thinner.

Yes, that's why I'd never do it. Modding a steel frame is one thing but the down tube on this is Aluminium, wide and very thin.

 

[99t4]

I imagine the bigger tires with the lower pressures would make for a smoother ride on a non sprung bike, would you think?

My area has lots of RR tracks running parallel with the road, and often diagonal, or parallel veering to diagonal, or curving, etc. Extremely slick in the rain. Unavoidable, especially with traffic pushing me around off my preferred line. I found the 2.35" width keeps me from getting trapped in the slots (instant crash!). Currently running Schwalbe Crazy Bobs at ~35 PSI.

 

[OlderGiantFan]

Oh, railroad track, yes, nasty pieces of work.

I found a vid of the Stance with a Hailong mounted so I know it's doable.



It was a YT short of a couple of years ago and the Guy had only a few views but someone asked what batt and he said


Link to bike vid:
youtube.com/watch?v=TuyADYDbzA0

I'm in email contact with a builder/supplier out here with a shop 150km away who is selling decent batteries under the company brand. I'm emailing now for the dimensions, it's a 48V 17Ah too. Best of all, Sony/Panasonic cells.

 

[99t4]

I found a vid of the Stance with a Hailong mounted so I know it's doable.

Same frame size as yours?

 

[Diggs]

Full suspension bikes have by far the best riding experience but it's a pain in the ass to find a frame where a big enough battery can fit without interfering with the rear suspension.

I've been looking to upgrade my ride but while I would love to have a full suspension bike, they can't take any loads in the rear. I ride with a rear rack, trunk bag and saddle bags. When I ride I usually go out all day so as a minimum I carry extra clothes/jacket, water, snacks besides the normal tire repair stuff and few tools. Too often I buy stuff when out and about (or pickup trash) and add that to the load. Since I do the vanlife thing now and then I frequently have a 10 lb. bag of ice strapped on the trunk bag for short periods. I just can't see a bike with rear suspension being able to do this so I guess I need to stick with a hardtail.

 

[99t4]

I've been looking to upgrade my ride but while I would love to have a full suspension bike, they can't take any loads in the rear

They can, just with more limitations. I routinely carry 10-15 lb. in mine every ride (clothes, tools, water, misc. etc.) and it has held up no problems. Need to use a good quality rack, beware of the limitations, and inspect frequently.

Sometimes I stuff an empty backpack into a pannier or bungeed to the rack to use when I know I will be picking up heavy additional items. Although I don't like riding with a backpack normally.

 

[Apartunis]

I've been looking to upgrade my ride but while I would love to have a full suspension bike, they can't take any loads in the rear.

Most can not. But it is possible. This model is out of production I think, and it was very expensive and German.

 

[OlderGiantFan]

Same frame size as yours?

A good point. A very good point! The XL has a one inch longer top tube and seat tube than the L and the Large has even a greater size difference compared to the Medium. Size Chart - Giant Stance 29 | Ivanhoe Cycles

Here is the size sticker on mine, up under the top tube in the triangle.



A screen grab off the vid



That looks like an M to me, what do you think?

 

[OlderGiantFan]

I've been looking to upgrade my ride but while I would love to have a full suspension bike, they can't take any loads in the rear...
I guess I need to stick with a hardtail.

I was going to build this current ebike project on a Giant Talon-1 hardtail, a beautiful bike I though when I bought it, though I've hardly ridden it. I could have, but then a full suspension flea got in my ear. I suppose with the HT at least you'll get a little warning when to lift your bum off the seat. I rode the Talon to a mates work once, about 10km away. After a couple of km It just didn't seem right on the road, and I scooted up onto the grassy footpath and finished my trip there. It really thrived on the grass and dirt, go figure.

I have some older precovid flatbar Giant Toughroads, great bikes for pure pedaling on the road. Anyway the SLX-1 comes/came with saddlebag frames on the outer forks and a neat rear rack. I have two of these bikes and with the older one I bought in 2015 odd I took the luggage stuff off. The other week in response to a question I took the rear rack and held it up over the back of the Talon hardtail and the supports and holes are a perfect match. Who would have though they'd have drilled those same holes on an MTB?




The Giant Toughroad


I'm not a BrandWhore, I look around, but I always come back to these because they fit my needs perfectly. The only issue with the first SLX-1 was it came with a 'composite' seat post. Plastic basically lol. I found it bobbed in all directions when I was spinning hard. I went back and bought the aluminum one that came with the base model version and it was fine. When I bought a replacement one in 202x it came with the aluminum post, guess they learnt their lesson. These are 'D' shaped posts, always perfectly aligned but more complicated to change heights on the road. The dropper post on the new dual suspension bike is great, you can make micro adjustments to your hearts content as you tool along.

 

[OlderGiantFan]

They can, just with more limitations. I routinely carry 10-15 lb. in mine every ride

Have you ever considered mounting gas struts up from the axles? To support the rear rack and allow it to stay relatively level under swingarm movement. They come in all sizes and lengths.

15 pound force at rest (full extension)

18.5" 15lb Fits Nitro Prop Gas Strut Spring Shock Lid Door Lift Support 6x15mm | eBay

The oil within the cylinder, when it is compressed or extended, moves from one side of the piston head to the other, providing a damping effect. PLACE the scale at the point the strut connects to the door / lid (at the bracket).

www.ebay.com

Customizing Gas Spring Force Curves

Customization of gas springs to achieve a specific force curve is common in specialized applications. Adjustable gas springs, which allow for tweaking the force after installation, offer flexibility and fine-tuning capabilities, ensuring that the final setup matches the exact requirements of the application.

Just a crazy idea... But what else can can I do? It's raining outside.

 

[99t4]

Have you ever considered mounting gas struts up from the axles? To support the rear rack and allow it to stay relatively level under swingarm movement. They come in all sizes and lengths.

No. Counterproductive. The rack stays level as it is only connected at the seatpost. I just don't overload it, and inspect it frequently. Commonly referred to as a seatpost rack?

This is the one I am currently using:

It has a 25 lb. capacity. IME, the low outriggers are a must, for securing the bottoms of the panniers to keep them from flapping into the wheel.

This one has proved itself a real winner for me. Good design, materials, and construction. Always loaded with 15-20 lb, no problems over several years, several thousands of miles. Even survived a few crashes.

Just a crazy idea... But what else can can I do? It's raining outside.

If I limited my riding to non-rainy days I'd go crazy too!

 

[99t4]

If you need higher load capacity, maybe a design like this, with added cantilever support would work? (Dropper post compatible)

From Tinker Tantrums: A Custom Seatpost Rack By Souvenir Cycles – Travis Engel

There are also racks for FS bikes that attach to the axles or fork stanchions, but I am not interested in adding even more unsprung weight.

https://oldmanmountain.com/

 

[Diggs]

I am not interested in adding even more unsprung weight.

Agreed! ...but those are the first racks I've see that can do that. Interesting.

 

[Apartunis]

If you need higher load capacity, maybe a design like this, with added cantilever support would work? (Dropper post compatible)

User "dogman dan" made something like that.

Strongest seat post rack

There is still something that i need to solve about full suspension bike rack. Most of them are rated 10 kg and some are 15kg (I mean the seat post model) Butthey are generally made of aluminium. and when we put let say a 48V 15Ah lifepo4 battery on it that weight around 17lbs + the charger 4...

endless-sphere.com

 

[OlderGiantFan]

No. Counterproductive. The rack stays level as it is only connected at the seatpost. I just don't overload it, and inspect it frequently. Commonly referred to as a seatpost rack?

I wouldn't have said counterproductive, not as far as the center of gravity for the load is concerned. But if you're used to the extra weight up there and find it no issue then all's fine hey

I'd go with something like this myself, attaches to the upper arms. It can be leveled to suit the bike's geometry. Though obviously it will rise and fall with the rear wheel, but that would not be an issue.

Topeak Tetrarack M - Quick - Mount Mountain Rack System. Max load, 12kg (26 lb)

Topeak Tetrarack M - Quick-Mount Mountain Rack System | BikesOnline AU

Enhance your mountain bike with the Topeak Tetrarack M, a quick-mount rack system designed for sturdy, non-permanent installation, ideal for carrying gear on rugged trails. Available now at BikesOnline AU.

bikesonline.com.au

 

[Diggs]

User "dogman dan" made something like that.

Thanks @Apartunis ! Interesting thread. You'd think in the 15 or so years since that thread there would be a plethora of better/heavier racks for full suspension bikes. Not so much.......

 

[99t4]

I wouldn't have said counterproductive

It's possible I misunderstood your proposal. Were you proposing I attach tailgate lift struts connecting the rear axle to the seatpost rack?

But if you're used to the extra weight up there and find it no issue then all's fine hey

The rack and panniers are located within a few inches of where common rear racks have been traditionally mounted on millions of bikes over millions of miles over decades. Not to say it couldn't be improved but it doesn't seem to be a problem?

I'd go with something like this myself, attaches to the upper arms. It can be leveled to suit the bike's geometry. Though obviously it will rise and fall with the rear wheel, but that would not be an issue.

It is an issue-- it increases unsprung weight with negative effect to performance, roadholding, handling, and comfort.

 

[OlderGiantFan]

It is an issue-- it increases unsprung weight with negative effect to performance, roadholding, handling, and comfort.

I see your point, I have never thought of unsprung weight as a factor in performance, but then I have never gone into full suspension on a pushbike before other than just blithely riding the one mid drive up the blacktop. Those rear racks would be the last thing you'd want on top of a heavy unsprung hub motor.

An interesting principle I learnt riding an Adventure motorcycle is the consequences of standing up over rough sections or sharp bumps. Basically as the suspension compresses and lifts the seat, you are not on it, and as you're legs flex your body becomes momentarily weightless as far as the bike is concerned. The effect over multiple rough points in quick succession is more complicated but the handling is greatly improved if you can keep your bum off the seat and allow your legs to act as shock absorbers too.