27.5” front 26” rear - Wheelbuilding

General Discussion about electric bicycles.
User avatar
Chalo   100 GW

100 GW
Posts: 9014
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

Re: 27.5” front 26” rear wheel

Post by Chalo » Mar 29 2021 10:56pm

Eastwood wrote:
Mar 29 2021 10:54am
OK that makes perfect sense! So that being said do you recommend that I put the elbow in on the left side to even up the tension or should I lace with both elbows out?
Elbows both “out” 45 : 55
left “in” right “out” 49: 51
putting the left elbow “in” the spoke tension is more even but my worry is side to side strength because each side elbows are both facing the same direction. I’m not sure if that should be a concern of mine?
Use the more even tensioned, more symmetrical spoking. You can lace all on the same side of the flange with radial or cross-1 patterns, so use that to your advantage. It doesn't matter which side of the flanges the spokes emerge from, but it matters how symmetrical they are.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

User avatar
MadRhino   100 GW

100 GW
Posts: 7428
Joined: Sep 03 2010 5:28pm
Location: Montreal QC Canada

Re: 27.5” front 26” rear wheel

Post by MadRhino » Mar 30 2021 8:42am

Eastwood wrote:
Mar 29 2021 3:48pm

...
Now with alternating “in and out” it seems that you wouldn’t be able to get the tension ratio as close, is that correct?
It doesn’t change a thing for spoke tension. The purpose of alternate lacing is to limit the spokes rubbing, or even bending at the cross. Yet, with hub motor flanges that are sometimes thick and drilled further from the edge, the J-bend shape and angle does make the spoke bend on the flange when laced outside. The rim width and offset drilling can compensate but when it doesn’t, it is better to lace all spokes inside of the flange. When the wheel need to be dished, one side can be laced inside and the other outside, sometimes permitting the use of equal length spokes for dishing.
Make it fool-proof, and I will make a better fool.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear wheel

Post by Eastwood » Mar 30 2021 8:53am

Chalo wrote:
Mar 29 2021 10:56pm
Use the more even tensioned, more symmetrical spoking. You can lace all on the same side of the flange with radial or cross-1 patterns, so use that to your advantage. It doesn't matter which side of the flanges the spokes emerge from, but it matters how symmetrical they are.
MadRhino wrote:
Mar 30 2021 8:42am
It doesn’t change a thing for spoke tension. The purpose of alternate lacing is to limit the spokes rubbing, or even bending at the cross. Yet, with hub motor flanges that are sometimes thick and drilled further from the edge, the J-bend shape and angle does make the spoke bend on the flange when laced outside. The rim width and offset drilling can compensate but when it doesn’t, it is better to lace all spokes inside of the flange. When the wheel need to be dished, one side can be laced inside and the other outside, sometimes permitting the use of equal length spokes for dishing.
Ok thanks guys! I’ll lace the wheel with left side elbows in and right side elbows out to achieve more even tension ratio and for dishing.

I finally ordered the spokes! after hours of critical thinking 😅
Thanks so much for all the input, very helpful!

Ianhill   100 MW

100 MW
Posts: 2535
Joined: Sep 25 2015 5:55pm

Re: 27.5” front 26” rear wheel

Post by Ianhill » Mar 30 2021 9:38am

I bet you had an adrenaline rush pushing the button like an ebay bid after all that effort.

Dont worry about the spoke heads they tend to fail with to much power over time even in a well built wheel theres a limit.

Kuberg freerider got a well setup rear wheel, little dishing fairly even spoke tension spoke heads alterante and got sapim 13g spokes on a trails 14 inch rim nice strong setup for competion use.

12kw for a year or so and 3 them spokes had ripped their head clean off with a mixture of to much power making them go slack fast and then not keeping on top of adjusting the wheel enough allowing them to move the head in the hub flange hole i suppose and rub through the spoke.

Lesson being keep on top of wheel maintenance, and motor becuase it chucked a magnet and kuberg want a £1000 for a motor and ive had 2 fools try rip me off want the bike for peanuts so thats a ruff subject at the moment.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear wheel

Post by Eastwood » Mar 30 2021 4:46pm

Ianhill wrote:
Mar 30 2021 9:38am
I bet you had an adrenaline rush pushing the button like an ebay bid after all that effort.
Yeah it was definitely relieving to finally get the spokes ordered after contemplating for several days, well maybe over a week 😅

Now it’s just a waiting game for all the parts to come in.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear wheel

Post by Eastwood » Mar 30 2021 4:47pm

MadRhino wrote:
Mar 30 2021 8:42am
Chalo wrote:
Mar 29 2021 10:56pm

What about these DT Swiss brass washers for the spoke heads? I know you guys recommended stainless but I’m wondering if these brass ones are strong enough?

https://www.ebay.com/itm/DT-Swiss-Spoke ... 890.l49286

Also what about this spoke prep by wheelsmith? Seems like the perfect solution since hub motors tend to loosen the spokes.
Wheelsmith Mini Spoke Prep, 15ml - blue https://www.amazon.com/dp/B0011VNDF6/re ... N3GNPQNC7X

Ianhill   100 MW

100 MW
Posts: 2535
Joined: Sep 25 2015 5:55pm

Re: 27.5” front 26” rear wheel

Post by Ianhill » Mar 30 2021 5:03pm

Ask chalos on washers material for the hub brass could be maliable and have a nice seat face last a long time give the spoke head more life so id see what he says on that one.
But for a torque arm get something decent 72v 60amp will work away at anything weak.
I found a local waterjet shop and long as i done the gcode file dimensions it cost £25 for the pair and a high carbon stainless was used so it didnt deform around the shaft.
I remember getting a metal splinter in my thumb deburring the thing and it took weeks to go.

User avatar
MadRhino   100 GW

100 GW
Posts: 7428
Joined: Sep 03 2010 5:28pm
Location: Montreal QC Canada

Re: 27.5” front 26” rear wheel

Post by MadRhino » Mar 30 2021 5:09pm

I use brass or alu washers on the motor flange, stainless in the rim. My favorite spoke prep is double boiled linseed oil, the one that is sold for wood finishing. Blue locktite or other mild thread prep are doing good but much more expansive.
Make it fool-proof, and I will make a better fool.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear wheel

Post by Eastwood » Mar 30 2021 5:18pm

MadRhino wrote:
Mar 30 2021 5:09pm
I use brass or alu washers on the motor flange, stainless in the rim. My favorite spoke prep is double boiled linseed oil, the one that is sold for wood finishing. Blue locktite or other mild thread prep are doing good but much more expansive.
Ok cool, I’ll look up double boiled linseed oil.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear wheel

Post by Eastwood » Mar 30 2021 5:22pm

Ianhill wrote:
Mar 30 2021 5:03pm
72v 60amp will work away at anything weak.
Yeah true :lol:
Also my max phase current is 150a
Ianhill wrote:
Mar 30 2021 5:03pm
I remember getting a metal splinter in my thumb deburring the thing and it took weeks to go.
Yeah metal splinters suck I get those from sheet rock/drywall screws.

markz   100 GW

100 GW
Posts: 12229
Joined: Jan 09 2014 11:38pm

Re: 27.5” front 26” rear wheel

Post by markz » Mar 30 2021 5:41pm

I bought a bottle from Home Depot, though mine is just BOILED LINSEED OIL (Not double boiled) and is 945ml or 1/4G and I think I paid $12cdn for it, check the paint aisle.
Eastwood wrote:
Mar 30 2021 5:18pm
Ok cool, I’ll look up double boiled linseed oil.

User avatar
Chalo   100 GW

100 GW
Posts: 9014
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

Re: 27.5” front 26” rear wheel

Post by Chalo » Mar 31 2021 12:04am

Eastwood wrote:
Mar 30 2021 4:47pm
MadRhino wrote:
Mar 30 2021 8:42am
Chalo wrote:
Mar 29 2021 10:56pm

What about these DT Swiss brass washers for the spoke heads? I know you guys recommended stainless but I’m wondering if these brass ones are strong enough?
I use hardware store washers. Stainless if they're available, brass if not, zinc-plated steel if brass isn't easy to get. The point is taking up the extra room in a hub hole that's too big for the correct spoke.

River City Fasteners in the Detroit area will sell you stainless washers in whatever size you need. They have tons of stuff on eBay.

https://www.ebay.com/itm/500-M2-Metric- ... 0953127040
Last edited by Chalo on Mar 31 2021 9:18am, edited 1 time in total.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

MartyMcfly1   1 mW

1 mW
Posts: 12
Joined: Jan 16 2021 3:57pm

Re: 27.5” front 26” rear - Wheelbuilding

Post by MartyMcfly1 » Mar 31 2021 4:41am

I'm running a MXUS 3KW TURBO 3t on my bike and love it, there is quite a difference in top end between the different winding variants of the MXUS. I'm running 24" on SAS halo rim and the acceleration is phenomenal. Wider rim on the back vs the front but both 24 inch. Smaller the better rim imo for lower motor temps, better rolling resistance and faster acceleration.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear - Wheelbuilding

Post by Eastwood » Mar 31 2021 10:02am

MartyMcfly1 wrote:
Mar 31 2021 4:41am
I'm running a MXUS 3KW TURBO 3t on my bike and love it, there is quite a difference in top end between the different winding variants of the MXUS. I'm running 24" on SAS halo rim and the acceleration is phenomenal.
Nice to hear!
I’m definitely looking forward to the fast acceleration and high torque of this motor. My current motor hits 50mph so I have plenty of speed but just missing that hard acceleration. Since the acceleration is phenomenal with the 3T I can only imagine how hard this 5T is going to pull! :o

Maybe you seen this video but they compare the QS 4T vs the 5T. Quite a difference in torque when they’re doing low speed burn outs.
https://youtu.be/n9fYtyzV4Do

For the top speed of this 5T, the motor simulator is showing around 53 mph with the 27.5”.. running a larger wheel because this is for my actual mountain bike.

How fast is your 3T, 70-ish mph?
Last edited by Eastwood on Mar 31 2021 10:08am, edited 3 times in total.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear wheel

Post by Eastwood » Mar 31 2021 10:07am

markz wrote:
Mar 30 2021 5:41pm
I bought a bottle from Home Depot, though mine is just BOILED LINSEED OIL (Not double boiled) and is 945ml or 1/4G and I think I paid $12cdn for it, check the paint aisle.
Chalo wrote:
Mar 29 2021 10:56pm
I use hardware store washers. Stainless if they're available, brass if not, zinc-plated steel if brass isn't easy to get. The point is taking up the extra room in a hub hole that's too big for the correct spoke.

River City Fasteners in the Detroit area will sell you stainless washers in whatever size you need. They have tons of stuff on eBay.

https://www.ebay.com/itm/500-M2-Metric- ... 0953127040
Thanks guys, very useful!

User avatar
MadRhino   100 GW

100 GW
Posts: 7428
Joined: Sep 03 2010 5:28pm
Location: Montreal QC Canada

Re: 27.5” front 26” rear - Wheelbuilding

Post by MadRhino » Mar 31 2021 10:18am

MartyMcfly1 wrote:
Mar 31 2021 4:41am
I'm running a MXUS 3KW TURBO 3t on my bike and love it, there is quite a difference in top end between the different winding variants of the MXUS. I'm running 24" on SAS halo rim and the acceleration is phenomenal. Wider rim on the back vs the front but both 24 inch. Smaller the better rim imo for lower motor temps, better rolling resistance and faster acceleration.
Yep, many advantages but...
A smaller wheel does not improve rolling resistance. Tire width, PSI, thread and gum do; so does lighter weight, better bearings, and LARGER wheel diameter especially. Off road, larger wheels are a huge advantage, enough to make a winner the ebike that has lesser power and top speed, simply because it does handle and corner better.
Make it fool-proof, and I will make a better fool.

Ianhill   100 MW

100 MW
Posts: 2535
Joined: Sep 25 2015 5:55pm

Re: 27.5” front 26” rear - Wheelbuilding

Post by Ianhill » Mar 31 2021 10:40am

Mad rhino your spot on by there.

Trend in world cup downhill has been bigger wheels over the years and its led to 29ers that are timed faster than the old 26.

Kuberg freerider got 20 inch wheels and their slow speed turn ability is good but as for rolling over bumps the front forks are working overtime got to give it to the dorados though they awsome bit of kit for 2012 tech.

Point being 1kwh got me 15miles tops it was WH per mile heavy.
Last edited by Ianhill on Mar 31 2021 11:53am, edited 1 time in total.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear - Wheelbuilding

Post by Eastwood » Mar 31 2021 11:34am

MadRhino wrote:
Mar 31 2021 10:18am
LARGER wheel diameter especially
Yes exactly this!
That’s the only reason I went with the larger wheel for the off-road aspect.
Well also helps a little with the top speed

User avatar
MadRhino   100 GW

100 GW
Posts: 7428
Joined: Sep 03 2010 5:28pm
Location: Montreal QC Canada

Re: 27.5” front 26” rear - Wheelbuilding

Post by MadRhino » Mar 31 2021 3:17pm

Eastwood wrote:
Mar 31 2021 11:34am
MadRhino wrote:
Mar 31 2021 10:18am
LARGER wheel diameter especially
...Well also helps a little with the top speed
Not really. I mean, when the fastest top speed is the priority, the larger wheel won’t do it because of the higher leverage that requires more power and makes lower efficiency. When you want to exploit the fastest possible speed that a motor can achieve, a faster winding with a smaller wheel is the way to go.

Like I said before, the larger wheel has an important advantage off road because it does ride and handle better, thus does not require slowing down as much to ride and corner over the rough and obstacles, giving a faster AVERAGE speed. Top speed is useless if achieving it does make the bike a slower average speed on the terrain that you ride.
Make it fool-proof, and I will make a better fool.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear - Wheelbuilding

Post by Eastwood » Mar 31 2021 5:10pm

MadRhino wrote:
Mar 31 2021 3:17pm

Not really. I mean, when the fastest top speed is the priority, the larger wheel won’t do it because of the higher leverage that requires more power and makes lower efficiency. When you want to exploit the fastest possible speed that a motor can achieve, a faster winding with a smaller wheel is the way to go.

Like I said before, the larger wheel has an important advantage off road because it does ride and handle better, thus does not require slowing down as much to ride and corner over the rough and obstacles, giving a faster AVERAGE speed. Top speed is useless if achieving it does make the bike a slower average speed on the terrain that you ride.
Well top speed is not my major priority, the off-road ability is. The 27.5 technically has faster top speed than the 26” so my point was I’m just gaining “some” additional top end speed with the slightly larger wheel. But yeah if my goal was speed I would’ve went with the 3T. That’s way to much speed for a regular mountain bike :wink:

According to the simulator.ca , 26” is around 47 mph. The 27.5” is around 53 mph
Both with the 5T winding

User avatar
MadRhino   100 GW

100 GW
Posts: 7428
Joined: Sep 03 2010 5:28pm
Location: Montreal QC Canada

Re: 27.5” front 26” rear - Wheelbuilding

Post by MadRhino » Mar 31 2021 5:32pm

The simulator is not giving reality numbers in that particular case. In the mountain practical usage, the larger wheel won’t give better top speed unless you feed the motor much higher power. Using the same controller and battery, the larger wheel is likely to be a tad slower top speed in mountain trails, and less efficient. BUT, its riding qualities will give a faster average speed.
Make it fool-proof, and I will make a better fool.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear - Wheelbuilding

Post by Eastwood » Mar 31 2021 6:37pm

:banana: bba
MadRhino wrote:
Mar 31 2021 5:32pm
The simulator is not giving reality numbers in that particular case. In the mountain practical usage, the larger wheel won’t give better top speed unless you feed the motor much higher power. Using the same controller and battery, the larger wheel is likely to be a tad slower top speed in mountain trails, and less efficient. BUT, its riding qualities will give a faster average speed.
Right, i’m not looking for top speed on mountain bike trails. When I’m referring to the top speed I mean on the streets, not dirt. My main focus with choosing the larger diameter wheel is for mountain bike purposes only. Then as a side note with the large wheel while riding on the street I will have more top speed vs running the 26” , slightly

If I were building a bike and the priority was Speed I would use motorcycle wheels on an Enduro stealth frame or something similar.

With this project the main focus is to keep it an actual mountain bike but suitable for street and sidewalk riding as well. “Most” of my riding is through urban areas on side walks etc. that’s why I recently chose the Schwab super Moto tires as they handle just like motorcycle tires. They actually grip decent on the dirt as well because of the 2.8 diameter, well dry conditions only. I’m sure they would slip all over the place in wet conditions, don’t do any wet riding on trails or on the street.
Last edited by Eastwood on Mar 31 2021 6:50pm, edited 1 time in total.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear - Wheelbuilding

Post by Eastwood » Mar 31 2021 6:45pm

MadRhino wrote:
Mar 31 2021 5:32pm
Also can I see a picture of your bikes? You have one for dirt and Street, nice!

JackFlorey   100 kW

100 kW
Posts: 1197
Joined: Feb 19 2020 7:22pm

Re: 27.5” front 26” rear - Wheelbuilding

Post by JackFlorey » Mar 31 2021 6:57pm

Just a general Q on this.

This is a pretty small change that will have a minor effect on bike geometry. You could make the effect almost zero by welding on some custom dropouts that drop the rear wheel axle a little lower. (Of course there may be issues with chainline, brake caliper position etc.)

What if you took this to an extreme? What if you kept the front wheel at 27.5" and made some long custom dropouts for the back and used a 12" wheel in the rear, such that the rear of the bike sat at exactly the same place, and the 12" wheel contacted the road exactly where the original tire would have? Obviously there'd be huge problems with chainline, brake caliper, climbover etc - but from a pure bike geometry point of view would you notice the difference?

I have no plans to do this, I am just curious from a bike-dynamics standpoint.

User avatar
Eastwood   100 W

100 W
Posts: 269
Joined: Jan 13 2021 2:48pm

Re: 27.5” front 26” rear - Wheelbuilding

Post by Eastwood » Mar 31 2021 7:20pm

JackFlorey wrote:
Mar 31 2021 6:57pm
Just a general Q on this.

This is a pretty small change that will have a minor effect on bike geometry. You could make the effect almost zero by welding on some custom dropouts that drop the rear wheel axle a little lower. (Of course there may be issues with chainline, brake caliper position etc.)

What if you took this to an extreme? What if you kept the front wheel at 27.5" and made some long custom dropouts for the back and used a 12" wheel in the rear, such that the rear of the bike sat at exactly the same place, and the 12" wheel contacted the road exactly where the original tire would have? Obviously there'd be huge problems with chainline, brake caliper, climbover etc - but from a pure bike geometry point of view would you notice the difference?

I have no plans to do this, I am just curious from a bike-dynamics standpoint.
This is a good idea to keep the geometry the same but in my case I want to keep the large wheel on the rear to be able to roll over objects easier.
That being said I am considering fabricating a whole new swing arm, something beefier maybe extended slightly. Depending on how easy it power wheelies tho.

But to answer your question I guess the geometry would stay the same but I’m sure the handling would change due to the smaller diameter wheel in the rear. Would be interesting to see and ride but I think it would throw off the handling. maybe a 20 inch wheel might be more doable but 12 inch would be pretty extreme

Post Reply