Help! Converting folder bike to cassette

[Peter.Bridge]

There seems quite a lot of 7 speed freewheel folding bikes with disc brakes (e.g. https://www.compass24.com/compass-folding-bike-20-inch-blue-415370/blue) which seems to get good reviews on bike forums.

If I added a hub motor,.my only concern would be the smallest freewheel cog is 14t. If I wanted a more relaxed pedalling 11 or 12 t smallest cog, I could use a DNP freewheel (which I have on my folding bike - it works great) but there seems reports that often these need replacing after. 2-3000 miles. I was planning on building this bike for a relative, so I was wondering if there was a more durable alternative ?
If I replaced the rear wheel with a cassette hub motor wheel and added a 7 speed cassette would that work ? Could I use the existing shifter / derailleur ?

 

[Woosh]

Yes, that would work

 

[Peter.Bridge]

Yes, that would work

What is the lightest one you do ? Is that the xf08c ? I was hoping for something lighter if possible - have you got anything hidden away anywhere ?

 

[SkyMonkey]

Sram 7 speed cassettes are still available in the UK.
They won't have the same choice of quality that their 10/11/12 speed cassettes have, but I always had good experiences with them in the past.
This one is 12-32: https://www.evanscycles.com/brand/sram/pg-730-7-speed-cassette-709518#colcode=70951803

A larger chainring would help too for lower cadence pedalling.
The one on that bike looks none too large.

 

[Woosh]

What is the lightest one you do ? Is that the xf08c ? I was hoping for something lighter if possible - have you got anything hidden away anywhere ?

DWG2NC. Same weight but easier to install. If you can wait until December, I will have the Tongsheng 85TS kits in stock. It's lighter and easier to fit, no need to install the pedal sensor. Just install the battery and drop in the motor wheel. Perfect if you have pressfit bb. I have been using it on my full sus bike in the last 6 months.

 

[Bonzo Banana]

A front hub motor would mean you wouldn't have to face the situation where the freehub mechanism fails on the hub motor and is difficult to replace. You would also have longer spokes on the rear wheel for more flexing and comfort which becomes more important on a 20" wheeled bike. Also ease of puncture repairs if the hub motor is on the front. Tyre wear will also be more even and you will have two wheel drive which can be beneficial on looser surfaces. If you go for a throttle only ebike kit then you can have all ebike components attached to the forks and handlebar assembly etc with use of a front rack that turns with steering so you have a very simple cable layout. It's legal to do so according to this;

DfT: Pedal cycles converted to ‘twist and go’ exempt from type approval – Pedelecs – Electric Bike Community

www.pedelecs.co.uk

Lots of positives to having a front hub motor as well as a few negatives. Overall I feel its the better option. Ebike kits with 20" front hub motors tend to be cheaper than those with freehubs. So it may not cost more to have to buy an additional rear wheel with a freehub. You also end up with a complete spare wheelset both front and back which might be easier to sell for a better price. Also because most of the riders weight is on the rear wheel not front, typically front hub motors are more reliable, bearings last longer. Of course this depends on the design but some of the manufacturers use the same bearings on both their front and rear hub motors where as typically on a normal bicycle the front hub bearings are smaller than the rear hub bearings I think as a general rule.

Personally I would look for a folding bike secondhand which already has a freehub some can go quite cheap. The Halford's Carrera Intercity is a brilliant folding bike that can go quite cheap secondhand. Also if you have a front hub motor you can go for a bike with hub gears like the Carrera Transit which have a brilliantly reliable 3 speed Shimano Nexus and a front hub motor will take even more wear off it to extend its lifespan possibly 3x. I've also seen a Go Outdoors Compass model go quite cheap on occasion and that is a brilliant freehub based folding bike that sold for around £300 new that you see go sub £100 occasionally. I can't remember the model name but this is it with Claris based gearing. Always worth looking out for cheap Dahon or Tern models too although the ones I see often cheap are the low end entry level models with basic freewheel drivetrains despite their original price of close to £500. You have to find them with some serious discounting secondhand for them to be good value I feel as they are often twice the price they should be from new.

The important thing about going for a front hub motor is you want a folding bike with front steel forks that way you shouldn't have to bother with a torque arm which makes changing front punctures much easier. I would say as a general rule most have front steel forks but occasionally you get aluminium front forks which is where often many Dahon and Tern models are unusable unless you use a torque arm which personally I would avoid.

 

[Peter.Bridge]

If you can wait until December, I will have the Tongsheng 85TS kits in stock. It's lighter and easier to fit, no need to install the pedal sensor. Just install the battery and drop in the motor wheel.

That sounds ideal, would the torque sensor work with a 7 speed cassette ?

 

[Bonzo Banana]

Sram 7 speed cassettes are still available in the UK.
They won't have the same choice of quality that their 10/11/12 speed cassettes have, but I always had good experiences with them in the past.
This one is 12-32: https://www.evanscycles.com/brand/sram/pg-730-7-speed-cassette-709518#colcode=70951803

A larger chainring would help too for lower cadence pedalling.
The one on that bike looks none too large.

In my parts storage I have both 11-34T and 11-36T 7 speed cassettes. The 11-36T cassette seems very rare but I seem to remember reading somewhere someone who had removed the second smallest cog from a 8 speed cassette (typically you would have 2 loose cogs that can be replaced) to make it a 7 speed cassette and the drivetrain had no problem shifting from the 11T cog to I think the 13T cog or maybe 14T cog. A 7 speed freehub isn't as wide as a 8 speed freehub so I think they are at the same pitch the cogs. I maybe remembering wrongly but might be worth checking. Apart from that the ETC 7 speed 11-34T cassette can be fairly commonly found, there are normally at least a few sellers selling it. These are steel cassettes so very hard wearing typically, a better lifespan that lighter higher end models that often have aluminium cogs for their larger cogs.

 

[saneagle]

The problem with DNP freewheels is that the pawls at the back get stuck, so you lose engagement. It's easily solved with a can of 3-in-one oil either as a preventative measure (best) or after it happens. Lay the bike on its side and squirt the oil in down the hole in the axle. Leave it for a bit to work its way through, then turn the freewheel backwards and forwards a few times. The freewheel will last forever if you do that every couple of months.

The problem with cassette motors is that they're usually wider, so more difficult to fit, and the rim needs to be off-set. They also have narrower stator and rotors, so not able to handle as much power as the freewheel version.

 

[esuark]

I`ve now done 10,000 miles with my DNP freewheel (hub motor). As saneagle says oil it. I had to do the same with the sturmey archer 3 speed on my Raleigh twenty when that became stuck.

 

[Peter.Bridge]

A front hub motor would mean you wouldn't have to face the situation where the freehub mechanism fails on the hub motor and is difficult to replace. You would also have longer spokes on the rear wheel for more flexing and comfort which becomes more important on a 20" wheeled bike. Also ease of puncture repairs if the hub motor is on the front. Tyre wear will also be more even and you will have two wheel drive which can be beneficial on looser surfaces. If you go for a throttle only ebike kit then you can have all ebike components attached to the forks and handlebar assembly etc with use of a front rack that turns with steering so you have a very simple cable layout. It's legal to do so according to this;

DfT: Pedal cycles converted to ‘twist and go’ exempt from type approval – Pedelecs – Electric Bike Community

www.pedelecs.co.uk

Lots of positives to having a front hub motor as well as a few negatives. Overall I feel its the better option. Ebike kits with 20" front hub motors tend to be cheaper than those with freehubs. So it may not cost more to have to buy an additional rear wheel with a freehub. You also end up with a complete spare wheelset both front and back which might be easier to sell for a better price. Also because most of the riders weight is on the rear wheel not front, typically front hub motors are more reliable, bearings last longer. Of course this depends on the design but some of the manufacturers use the same bearings on both their front and rear hub motors where as typically on a normal bicycle the front hub bearings are smaller than the rear hub bearings I think as a general rule.

Personally I would look for a folding bike secondhand which already has a freehub some can go quite cheap. The Halford's Carrera Intercity is a brilliant folding bike that can go quite cheap secondhand. Also if you have a front hub motor you can go for a bike with hub gears like the Carrera Transit which have a brilliantly reliable 3 speed Shimano Nexus and a front hub motor will take even more wear off it to extend its lifespan possibly 3x. I've also seen a Go Outdoors Compass model go quite cheap on occasion and that is a brilliant freehub based folding bike that sold for around £300 new that you see go sub £100 occasionally. I can't remember the model name but this is it with Claris based gearing. Always worth looking out for cheap Dahon or Tern models too although the ones I see often cheap are the low end entry level models with basic freewheel drivetrains despite their original price of close to £500. You have to find them with some serious discounting secondhand for them to be good value I feel as they are often twice the price they should be from new.

The important thing about going for a front hub motor is you want a folding bike with front steel forks that way you shouldn't have to bother with a torque arm which makes changing front punctures much easier. I would say as a general rule most have front steel forks but occasionally you get aluminium front forks which is where often many Dahon and Tern models are unusable unless you use a torque arm which personally I would avoid.

Yes, I have a 6 speed folder with front hub motor (akm 74) and the Woosh bag battery, and I used a dnc 7 speed freewheel (11-32t) - I only use the first 6 gears, and it only has a 6 speed shifter. Don't need the lowest gear with the motor. It's great and gives a more relaxed pedalling cadence. That has a front steel fork. Unfortunately it only has rim brakes.

I have looked at the Carrera Intercity disc 8 and 9, both have alloy forks and the 9 has unusual rim size that only allows very narrow tyres.

If I could find a folder with disc brakes, cassette and steel front forks I would be tempted to do a front hub conversion.

 

[Woosh]

@saneagle honestly, it took me 1 minute to drop the 85TS wheel in my frame. The dropout is 135mm. The dwg2nc has the same 135mm dropout. It's never been an issue.
When you use the bike every day, upgrade to cassette.

 

[guerney]

There seems quite a lot of 7 speed freewheel folding bikes with disc brakes (e.g. https://www.compass24.com/compass-folding-bike-20-inch-blue-415370/blue) which seems to get good reviews on bike forums.

Looks very much like the later Dahon Jetstreams, apart from the lack of "full suspension", the effectiveness of which I don't know but am curious about. I don't think I'd buy one, because that front suspension fork seems almost impossible to find parts for.

If I could find a folder with disc brakes, cassette and steel front forks I would be tempted to do a front hub conversion.

Rarely, 8 speed cassette Dahon Jetstreams with disc brakes turn up on ebay. I think the front forks are steel, but you'd best check. Much like this, but folding. How the full suspension Jetstream rides I haven't the faintest - you'd have to ask @saneagle, he owned and converted one to rear hub motored. Some Jetstream models forgo the front suspension fork, others don't have rear suspension either.

Dahon Custom Built Groove P9 Disc

This bike is fitted with an 9 speed Shimano Drive system and a Dahon Disc wheelset

foldingbike.biz

 

[saneagle]

@saneagle honestly, it took me 1 minute to drop the 85TS wheel in my frame. The dropout is 135mm. The dwg2nc has the same 135mm dropout. It's never been an issue.
When you use the bike every day, upgrade to cassette.

Which frame was it? was it an off-set one from an electric bike? How long did it take to off-set the rim to get it in the centre?

 

[Woosh]

Andy does the conversions for customers in recent years. The last conversion I did from freewheel to cassette was a few years ago. I did not take much time to change the gear shifter. No change to the motor wheel.

 

[Peter.Bridge]

Which frame was it? was it an off-set one from an electric bike? How long did it take to off-set the rim to get it in the centre?

If I was replacing a non electric 7 speed freewheel rear wheel with a hub motor rear wheel with a 7 speed cassette, would you expect that to be an easy job ?

 

[saneagle]

If I was replacing a non electric 7 speed freewheel rear wheel with a hub motor rear wheel with a 7 speed cassette, would you expect that to be an easy job ?

Everything is easy when you know how and have the time and tools to do it. My thinking is that you're trying to solve a problem that doesn't exist. You're DNP freewheel won't fail if you keep it lubricated. If you needed a cassette motor for some other reason, it might be worth fitting one, or if you have a new conversion to do that already has a 9-speed or 8-speed cassette and you can't be bothered to change the shifters and derailleur, that would also make sense to fit a cassette motor. My first choice would always be to fit a freewheel motor if possible because the motor can handle more power and you don't need so much off-set in the rim.

Some frames have more of an off-set built into them, especially ones designed for rear hub-motors, and some Chinese sellers already build a decent off-set when they put a cassette motor into a wheel. It's not an exact science concerning what you get and what you have to do.

 

[Cadence]

If I was replacing a non electric 7 speed freewheel rear wheel with a hub motor rear wheel with a 7 speed cassette, would you expect that to be an easy job ?

I've not done it, but I do know that if you fit a 7 speed cassette to a modern (8,9,10 speed) non-electric hub you have to fit a spacer behind the cassette (available from SJS Cycles). Other than that I don't see any problems, assuming that the bike has at least 135mm dropout spacing.

 

[Peter.Bridge]

My thinking is that you're trying to solve a problem that doesn't exist. You're DNP freewheel won't fail if you keep it lubricated.

Point taken and I will lubricate the DNP freewheel on my folder. The proposed bike is for an older relative that does not live locally to me and I wanted her to have the minimum of maintenance to do

 

[saneagle]

Point taken and I will lubricate the DNP freewheel on my folder. The proposed bike is for an older relative that does not live locally to me and I wanted her to have the minimum of maintenance to do

You know the pawls in motor freehubs can stick as well. We've probably had as many incidents of that on this forum as we have of freewheels sticking, though DNP ones do seem to be a bit worse than normal freewheels if you don't maintain them.