Cecil's ride - 2017 Raleigh Kodiak 1 full suspension 27.5 plus bike with 750w TSDZ2 mid drive and rear rack dog carrier

[John and Cecil]

Hi, I figured I would make this thread in case anyone is interested in converting a Raleigh Kodiak 27.5 plus bike to mid drive. These bikes were apparently discontinued by Raleigh and can be bought fairly cheap if you can find one. It has a 73mm bb and the tsdz2 fits well. With the 42 tooth chain ring there is no need to resize the chain either. There is no place to mount the torque arm so I used a large heavy duty zip tie and so far it is working fine however I do not have full power available yet due to the small battery I am currently using. So far I am into this project about $1000 including the new bike, motor, rack, and mini 2ah battery and charger.

The motor does not like the 14s battery though and I can only charge it to a maximum of about 55.6v for it to work with my motor. We plan on upgrading the battery after we move. The current battery is an ego 56v 2ah power tool battery held on temporarily with velcro. There is not a lot of room inside the frame for a battery though.

The rear rack is an M-Wave One-for-all rack and it is mounted to the frame using a pair of plastic bimini top mounts I had lying around. I had to purchase a pair of salsa extended rack stays for the front and they are currently mounted with 1" rubber coated wire clamps however I plan on making some custom heavy duty clamps to replace them in the future. The rack appears to be capable of carrying about 50lbs of cargo.

Cecil's box is a motorcycle carrier I had already built and it was modified to be lighter, and it has a set of Scooter Logic insulated (cooler) saddle bags mounted to the side. His box with the saddle bags weighs about 10 lbs so I eventually plan on upgrading it to something lighter, but it is very strong and designed to withstand a fairly substantial impact.

I plan on installing a few more upgrades in the future including headlight(s), taillight, possible turn signals/flashing hazard lights, mirror, front storage bag or small rack, comfortable cruiser seat, etc.

I took a few pictures, but it is a work in progress:

 

[fechter]

What kind of motor is that?

 

[SlowCo]

What kind of motor is that?

He writes "tsdz2" in the title and third sentence of his post... :wink:

 

[John and Cecil]

What kind of motor is that?

Yes it is a 750w tsdz2 48v motor with 73mm bb. It was $355 from pswpower.

 

[John and Cecil]

Cecil ready to go for a ride. Unfortunately the brackets slipped out of the rubber casings holding the front rack stays to the frame and scratched up the frame. I guess I will be making heavier duty brackets this week.

 

[John and Cecil]

Well I made new brackets to securely hold the front of the rear rack stays and they are working well. They are just some heavier duty steel stock bent to fit the frame and then dipped in plasti-dip rubber coating. The rack is solid now and can support 50 lbs (street riding).



I also cut a small piece of a camping mat for the bottom of the dog carrier for Cecil's comfort.



I ordered a handlebar bag and a mirror that we will add next week. I also need to order a more comfortable cruiser seat. I pumped up the tires today after I made a homemade presta adapter and it is working so much better now with the higher pressure in the tires. I also opened up the Ego 2ah battery and installed permanent wires and I will probably store the battery in the handlebar bag once it arrives.

The Kodiak is turning out to be a really nice street bike and the suspension is nice for hitting unexpected bumps going down a hill at 40mph





We did over 12 miles today on 2 battery charges (170watts).

 

[John and Cecil]

Well we have been taking the bike off road and hitting some larger bumps and lower supports for the rear rack are starting to bend (FAT CECIL!). I guess I will need to replace the aluminum lower rack struts with something longer that extends all the way up inside the rack (faulty manufacturer design). The rack is supposed to hold 50lbs, but when fully extended the lower struts do not extend far enough insdie the rack. I wish I could find some 1' long 10mm rack struts but it looks like I will have to make something.

 

[Marin]

While your beefing up the rack Cecil wants some suspension, your hogging all the shocks on your end, maybe an air bag to sit on, as long as it doesn't work like a whoopee cushion,

 

[John and Cecil]

While your beefing up the rack Cecil wants some suspension, your hogging all the shocks on your end, maybe an air bag to sit on, as long as it doesn't work like a whoopee cushion,

There is nothing I can do about suspension for him. He is way too heavy with his box to mount to the seatpost. The rack, box, and Cecil weigh close to 40lbs plus I carry some items in the side bags so it needs to support up to 50lbs. He does have a foam camping sleeping pad that he sits on. He seems comfortable, he will let me know if he is not comfortable.

I originally considered mounting the front of his carrier to the seatpost with a hinge and the rear of the rack to the rear frame by the wheel with ball joints or something so it can pivot with the suspension. I think it would be very difficult to get that to work properly with 40-50lbs and his box would constantly by tilting forward and backwards when the suspension moves. To truly utilize the shock the box would have to be mounted only to the seatpost and front portion of the frame, I don't think that is possible with 40lbs of weight - especially over bumps.

I have a pair of old drawer slides lying around. i think I will try cutting them down and using them as the lower rear rack supports, perhaps they will be stronger. I really need 300mm x 10mm diameter solid aluminum rack stays but I don't think they make them. I have to be done by tomorrow though, we have to travel 10 miles round trip to get Cecil his rabies shot and the bike is our only transportation.

 

[amberwolf]

There's a lot of threads about racks you should read thru, to give you ideas on how to fix the problem, and about how rack weight ratings don't mean much (such as, if you're riding on a completely flat road totally straight without wiggling it via pedalling/etc., then probably most of the racks can hold what they say they can, but when you hit a bump, you multiply the weight that's on the rack by the forces involved, which are not all vertical depending on the angle you hit the bump at, then you get into pedalling wiggle to fatigue the rack, etc.).


That said, you could build a rack that is supported not from the seatpost itself, but from the frame, that uses the suspension both for Cecil's comfort and to minimize stresses on the rack itself.

It'd use 1" square 1/16" (maybe 1/32") wall steel tubes on either side of the main frame, that run from the downtube/toptube intersection at the headtube both in front of and behind it, back across the top of the short curved tube at the point just in front of the seatpost, back to the rear of Cecil's box.

(EDIT: the start point above probably won't work and leave room for suspension movement, but maybe from just below the downtube would, clamped to the downtube and the headtube itself just above the crown race--see attached pic for one possible idea with straigth tubes, curved tubes would give you more swingarm clearance, etc)

These would cross connect to each other at those two (three) points, (preferably welded to each other, as the frame is probably aluminum and you wouldn't want to weld to it. If you have to you could bolt them together, but you'll need to use tubes inside the bolt holes inside each tube and between each tube as spacers so the walls don't crush).

U-bolts can then be used to clamp the rack to the frame itself, with metal plates shaped to fit the curves of the frame tubing between the U-bolts and the frame tubes to spread the load over as much surface area as practical.

Then a pair of tubes would run diagonally forward and down from the rear tips of the tubes above to the BB area of the frame, and be U-bolted to that (or the seattube above it, if the middrive makes it impractical to directly connect to the BB shell). Because of the swingarm, you'd probably have to gently curve these tubes outward and then back inward, so they clear the swingarm in it's full travel up and down.

If you don't use any rear triangulation to the BB area, it'll be a lot less sturdy and need thicker wall tubing to do the same job.

Then you could remove the rack's insufficient swingarm-mounted supports, and clamp or bolt the rack to these twin tubes instead.


Then you could probably carry Cecil, cargo, *and* a human on the rack without breaking it.

You could probably get away with thinner wall tubing, but I've tended to go for certainty and heavier rather than chancing anything.

 

[John and Cecil]

....

Thank you. I understand what you are saying. I thought along those lines originally but I cannot do anything like that now. The reason we have a full suspension bike is so it can be taken apart and stuffed into airline size suitcases. Eventually after we settle in overseas I will probably build a new cargo bike with an extended hardtail frame.

My other idea which I have yet to try is to make a heavy duty seatpost that would extend all the way into the frame, then after it exits the frame it would bend backwards about 80 degrees so it was horizontal and would extend back about 2 feet. Then I would mount a seat to the bend point for me and mount his box on the back. I could add 2 struts on a seatpost rack clamp to help reinforce it a little. I figure if a seatpost rack would handle 20lbs something like this should handle double that. Still it puts a lot of stress on the frame with all that leverage.

I think his current rack is not too bad though, the design seems durable it just needs heavier duty brackets to withstand the bumps. I am trying the drawer slides for now, they seem like they might be a little stronger.

 

[John and Cecil]

Well we are back in action. The drawer sliders are holding up well (so far), I think they are stronger than the old ones for weight coming down on them from above, but perhaps not as strong for side to side forces. I also put our battery in the handlebar bag. With Cecil sitting over the rear portion of the rear tire the front end feels extremely light even with the small battery. I think we can eventually carry a 20ah battery up there and not compromise handling We have a long trip tomorrow afternoon so we will be taking it easy until then. Poor Cecil, he has to get a shot It sucks that they force him to get a toxic (and unnecessary) rabies vaccination.

 

[John and Cecil]

Well I had to make some modifications to Cecil's carrier. We broke the long salsa upper rack struts right at the bend points, it appears they lose some strength at those points. I replaces them with the salsa 370mm 8mm straight upper rack struts. I also ordered some 8mm inner/10mm outer stainless steel tubes and when they arrive I will attempt to slide them over the rack strut with epoxy to make them stronger. I also added a heavy duty cable tie to the bottom of the seat and to the front of the rack as an emergency support in case we break a strut in the future.

Also the front upper brackets have been slipping and sliding down the forks over time. I was going to use a little epoxy but instead I have a heavy duty cable tie holding it in place.

Cecil has been sitting up against the back of the carrier and he was not very comfortable so I added a thick padded backrest for him that sticks up a few inches higher, and I also added a padded floor for his box with camping bedroll material covered in marine grade vinyl. He is very happy with his new seat and he is much more comfortable.

Oh I added a comfort seat for myself too We have a new 34t chainring on order too, hopefully that will help us climb steeper hills. The 42t chainring is a bit too fast for climbing hills and we don't need to do 30mph at 90 rpms in 1st gear, I cannot ride on flats any faster than 25mph with all the weight we are pushing along with 3" wide tires.

We have 300 miles on it so far!

 

[fechter]

A good design for a rear rack on a full suspension bike is something a lot of us would like. One that bounces along with the rear wheel is not ideal for many reasons. Something cantilevered from the main frame would be much nicer but hard to make easily.

 

[John and Cecil]

Yes, I understand. It does not matter too much for us though since this is really a street and smooth trail bike. It is handling pretty well but the long 8mm aluminum rack struts are not really that sturdy. Another option would be a "hinged rack that is attached to the frame near the seat post and also at the rear wheel and it pivots as the suspension moves. I think a rear rack attached only to the front frame and able to support at least 40-50lbs, especially when the weight needs to be extended back quite a bit from the rear of the seat, would probably be best if built upon a heavy duty bike frame like a downhill bike. I do think there is potential to have a post extend out of the seatpost tube and bend back 75 degrees or so parallel with the ground and then have a couple side braces to help keep it aligned. It would be difficult to mount a seat but it would use the entire depth of the seatpost tube as leverage and should be able to handle quit a bit of weight.

A hardtail would probably be a better option with seatpost suspension but fs was our only option as it also needs to be able to be taken apart and stuffed into airline sized suitcases when we move.

 

[John and Cecil]

A good design for a rear rack on a full suspension bike is something a lot of us would like. One that bounces along with the rear wheel is not ideal for many reasons. Something cantilevered from the main frame would be much nicer but hard to make easily.

Do you know anyone that has tried a very sturdy bar that extends down into the seatpost and then bends backward (or a welded 75 degree +/- angle point) over the rear wheel with a seat mounted on the bend point? Pretty much build a rack frame that slides all the way down into the seat tube on the frame and allows a seat to be attached to it (replaces the seat post). I think this design might have potential without the need for welding the frame as it uses the entire seatpost frame for leverage. A sturdy mount can be attached around the frame a little below the top of the seatpost with 2 support struts to help keep the rack aligned and give it a little more support.

a quick sketch, the bent post extends all the way down into the seat post tube:

 

[fechter]

There are quite a few racks that attach to the seatpost like this one.



The problem is with any kind of load, they tend to fail or cause the seat post to fail. But if you could add a diagonal brace to someplace lower on the frame, it might handle a decent load.

 

[John and Cecil]

There are quite a few racks that attach to the seatpost like this one.

Seatpost Rack.JPG

The problem is with any kind of load, they tend to fail or cause the seat post to fail. But if you could add a diagonal brace to someplace lower on the frame, it might handle a decent load.

That is not the same. A rack mounted "around" a seat post tube is not the same as a tube stuffed all the way into a seat post tube with a bend in it. That rack uses about 1" of seat post tube for leverage, what I am suggesting uses over a foot of tube as leverage. Do you understand? My concept would be theoretically be able to carry much greater weight depending on the quality of the frame welds. You are using the existing frame welds to the top and bottom of the seat post to hold the weight.

I guess it depends on the bike frame too, my seat post frame is very strong at the welds. If you look at the pic above at my bike I have an extra tube supporting my seatpost tube (triangular frame below the seat).

 

[John and Cecil]

The problem I see is this. Seat posts are crap. Why design a rack that mounts to a seatpost. Build a rack that replaces the seatpost with a heavy duty post that inserts all the way into the frame. Then use those cheap seatpost rack mount design for some added support. Then mount the seat to the rack. If you want a solid rack you need to put the seat on the rack, not put the rack on the seat...

 

[fechter]

Yes, the ones that wrap around the seat post are generally crap for moderately heavy loads. They usually break where the rack is welded to the clamp going around the tube.

Now I see what you're saying. If you replace the seat post with a stronger one that goes way down the seat tube, then it should be pretty sturdy. It would still be good to have a second attachment point so it becomes triangulated, but if you use sufficiently strong (heavy) material, it may not be needed.

 

[John and Cecil]

Yes, the ones that wrap around the seat post are generally crap for moderately heavy loads. They usually break where the rack is welded to the clamp going around the tube.

Now I see what you're saying. If you replace the seat post with a stronger one that goes way down the seat tube, then it should be pretty sturdy. It would still be good to have a second attachment point so it becomes triangulated, but if you use sufficiently strong (heavy) material, it may not be needed.

Yes exactly. The triangulation points also should help with sideways movement, because the weakness of the post will be that it might want to rotate (like point to the side instead of to the back). I think it would be possible to make a 40lb capacity rack like this, I wish I knew someone that could bend a 42" heavy duty seatpost (maybe stainless steel) so it would extend into the frame 18" or so and then bend sharply back and parallel with the ground over the rear tire. Then mount your seat and rack to that. In theory I think it should be quite strong and not very complicated to build if you can bend large tubing.

 

[John and Cecil]

Wile E Coyote is going back to the drawing board. The long straight Salsa upper rack struts are holding up better than the bent ones, however today the welds on the rack itself let go.




Thankfully the heavy duty cable tie attached to the seat did it's job and kept the carrier in place! Actually having the front of the rack attached to the seat post and having it tilt with the suspension is probably not a bad idea either. I am going to toss the rack and bolt aluminum L brackets to the bottom of his carrier and then mount the upper and lower struts to that. It looks like I will now have replaced just about every part of the original rack and we only have 400 miles so far. 50 lb weight capacity my foot!

 

[John and Cecil]

Well the Looney Toons are back in action. I tossed the entire rack and mounted aluminum L brackets to the bottom of Cecil's carrier. It is getting kind of heavy so I removed his upholstered floor and went back to a piece of camping mat. It probably weighs close to 15 lbs with the saddle bags and rack stays, hardware, etc. Eventually I will have to try to come up with a more lightweight yet safe solution.

The new parts need to be painted black but we are going to put some miles on it first to make sure it is up to the challenge. I made it wider than the original rack, and we have the emergency cable tie in place in case we have another upper strut failure. Initial impression is that it is sturdier than with the original rack.

 

[amberwolf]

I recommend moving those L brackets outboard to the outer edges of the carrier base. This should help "triangulate" the support structure for side-to-side loading, both front and rear, which should make the rear "wag" a bit less (which means less cyclic stress on the joints).

If you can make a "wedge" (wood, metal, plastic) to fit between the top of the L bracket face and the bottom of the carrier base, so the L points inward at the bottom, so that the supports are still meeting it parallel to the vertical of the L bracket, it'll remove the need for a bend in the supports there (they're stronger without the bend).

Similarly, if you can make a wedge between the bike frame connection point and the support, it would help there, too. However, you'd also have to change the angle of the bolt and that's probably not possible. Or use two wedges, in opposite directions, so the bolt still goes straight thru the frame point and wedges, but the support is clamped at an angle between the wedges.

 

[John and Cecil]

I recommend moving those L brackets outboard to the outer edges of the carrier base. This should help "triangulate" the support structure for side-to-side loading, both front and rear, which should make the rear "wag" a bit less (which means less cyclic stress on the joints).

If you can make a "wedge" (wood, metal, plastic) to fit between the top of the L bracket face and the bottom of the carrier base, so the L points inward at the bottom, so that the supports are still meeting it parallel to the vertical of the L bracket, it'll remove the need for a bend in the supports there (they're stronger without the bend).

Similarly, if you can make a wedge between the bike frame connection point and the support, it would help there, too. However, you'd also have to change the angle of the bolt and that's probably not possible. Or use two wedges, in opposite directions, so the bolt still goes straight thru the frame point and wedges, but the support is clamped at an angle between the wedges.

Thank you I understand, and you are correct that I would like a little more side to side stability. Since the carrier itself is strong enough on it's own I can probably make 4 small brackets instead of 2 long ones and mount them at or near the corners of the hardwood carrier to attach to the individual struts. I have been thinking about replacing the round aluminum upper struts with another set of the steel drawer sliders like I used on the bottom rear too.

I will give your suggestions some thought and see if I can triangulate the support structure. You have a very good grasp of mechanical/structural engineering.