Can I add a single speed freewheel on my gearless hub motor?

Hi ESFMs,

I'm in the process of tidying up my gearing system. I'm about to remove my front derailleur as it always has me stuck on the second cog no matter how much I tighten and adjust my cable to get her back on that larger cog.

Anyway, in the process of doing that, I'm also considering my 7 speed freewheel on the back that's always on that second smallest gear (it would be the smallest if my chain didn't get in the way of a bolt from my torque arm).

Seeing as I never need to shift gears, I was wondering if I could replace my 7 speed freewheel with a single speed. But I'm concerned about whether that will mess with the spacing of my dropout, whether there are any single speed freewheels that will fit my hub and anything else I can't currently foresee.

Anyone with this kind of experience? What do I need to know before I go and buy a single speed freewheel and chain?

Clinton

Your hub motor must have a standard freewheel screw-on mount. That is the most common freewheel thread, so almost any single freewheel will fit. From 4$ to 110$, you have a lot of choice.

Yeah, I might be over thinking it. I just remembered that the axle will determine the spacing. So, no worries there.

So, the thread for the freewheel on my hub should match up to standard freewheels?

The problem here is that your chain.. from the largest front sprocket, to the single speed sprocket, is going to be at a serious angle constantly. A single speed freewheel is also going to have a lower reduction ratio.. the smallest you will find is around 15t.

I'd recommend keeping the 7 speed freewheel on there if possible so that you can have a nice straight chainline between the big front sprocket and the small rear sprocket.

You can buy freewheel spacers, I have seen those for sale.
[strike]They were probably fixed gears and not freewheel.[/strike]
I found freewheel spacers online. Its just more money then just installing a 5/6/7 speed freewheel.

When we go single, we tune the chain line aligned, matching the proper chain size, and desired ratio; replacing both the chain ring and the freewheel, normally using BMX chain, and replacing the derailer with a chain tensioner. So yes, it is expansive if we do it good with quality components. Yet, some pretty cheap freewheels are available that will match your actual chain size. You can space it to align the chain line, and lock your derailer to make it a tensioner.

I'd go with a two speed freewheel. Either white industries, or a Surly dingle.

Lose the derailleur's, cables and shifters. Just need a chain tensioner (or use the rear derailleur if price is a concern )

You now have a 2-speed 'manual' and some wiggle room in your gearing.


Or if you keep both front cogs and the rear derailleur (to allow enough chain slack compared to a tensioner), you would have a 4-speed manual. High-high, high-low; low-high, low-low. Hehe

markz said:

You can buy freewheel spacers, I have seen those for sale.

Click to expand...

I hear those are kinda janky.
The freewheel to hub plate can be a little weak on some motors too..
bad combination of design factors, unfortunately.

If you're trying to shave weight, just take an angle grinder to a 7 speed freewheel and lop those other gears off.. you'll only save ~100g of weight though, lol.

You got a good point there on jankiness, maybe the added torque with gear so far out adds to damage to cover plate.

Funny you should mention the grinder modification on the freewheel, I have done that.

neptronix said:

markz said:

You can buy freewheel spacers, I have seen those for sale.

Click to expand...

I hear those are kinda janky.
The freewheel to hub plate can be a little weak on some motors too..
bad combination of design factors, unfortunately.

If you're trying to shave weight, just take an angle grinder to a 7 speed freewheel and lop those other gears off.. you'll only save ~100g of weight though, lol.

Click to expand...

I saw 12T freewheel on Ebay and I saw a 14T freewheel live. I'm using a 16T one, but I found out there are some incompatibility between the threads, the freewheel just stuck at the halfway on the hub, I had to make a thread die from an old freewheel to fix the thread on the hub motor, however it was just perfect, but the thread die helped me to screw it on the hub. For chain aligment you can use wider or narrower bottom bracket.

Lot of trouble when one can just use a DNP 11 sm. tooth free wheel and leave it on the sm. cog. That's what I do and since I'm not shifting, the 11T gear lasts longer. As mentioned above, if one feels they want a "cleaner look" or less weight, just cut off a few of the larger gears. That's what I did w/ my first DNP, but on the second I didn't bother. Really, what's the point of removing a few ounces when my motor weighs 11 pounds.