How to pedal assist when the engine is engaged?

[rsmith]

Hi there.
As you can see, I am new to the forum and am finding it really interesting. I've been contemplating an engine kit for a while, but only now have I raised enough cash. The one questio haven't seen covered is the matter of being able to pedal assist when the engine is going. I've heard people say that it is normal, for when the clutch is engaged, you are unable to turn the bicycles pedals. I live in a hilly area, where pedal assistance would be necessary. Also when riding over rough ground, alternative pedal positions would be useful. I am a competitive cyclist, so am quite happy to pedal assist, but is this possible when using a standard kit, or would I need a specialist freewheel? Some further information that you may need to help me is that I will either use a disk brake mount to hold the rear sprocket in place, but I also have a flip-flop rear hub spare, should it be needed.

Anyway, if you have any suggestions, I would be really appreciative. Keep up the good work.
Regards, Rob

 

[TigerToothBikes.com]

Hi there.
As you can see, I am new to the forum and am finding it really interesting. I've been contemplating an engine kit for a while, but only now have I raised enough cash. The one questio haven't seen covered is the matter of being able to pedal assist when the engine is going. I've heard people say that it is normal, for when the clutch is engaged, you are unable to turn the bicycles pedals. I live in a hilly area, where pedal assistance would be necessary. Also when riding over rough ground, alternative pedal positions would be useful. I am a competitive cyclist, so am quite happy to pedal assist, but is this possible when using a standard kit, or would I need a specialist freewheel? Some further information that you may need to help me is that I will either use a disk brake mount to hold the rear sprocket in place, but I also have a flip-flop rear hub spare, should it be needed.

Anyway, if you have any suggestions, I would be really appreciative. Keep up the good work.
Regards, Rob

Hi Rob,

With the "HT" midframe two stroke, sometimes referred to as a "chinagirl", pedal assist is always possible and depending on setup, required for particularly steep inclines. I am not sure i have ever heard of an engine setup whereby the user loses the ability to turn the cranks.

All the best and welcome to our "gang"

 

[rsmith]

Thanks for the quick reply. That's a relief. Undeniably, what you have said is correct, and I suspected that that was the case. However, could you explain to me what this is for?

http://cgi.ebay.co.uk/FREEWHEEL-sprocket-WHEEL-for-Bicycle-bike-engine-kits_W0QQitemZ300283129120QQcmdZViewItemQQptZUK_Bikes_GL?hash=item300283129120&_trksid=p3286.c0.m14&_trkparms=72%3A1298|66%3A2|65%3A12|39%3A1|240%3A1318

Thanks again, Rob

 

[rsmith]

FREEWHEEL sprocket WHEEL for Bicycle bike engine kits on eBay, also, Bikes, Cycling, Sporting Goods (end time 26-Jan-09 09:35:20 GMT)

 

[TigerToothBikes.com]

No sweat, I actually have a spare one of those from a four stroke "experiment". This set up is only for engines with centrifugal clutches. It allows the rear wheel to operate without constantly turning the chain and gearbox, thereby reducing resistance for normal pedalling. Not essential, because reistance is hardly detectable and with the clutch disengaged it doesn't matter.

 

[Dan]

Howdy RSmith, good to meet ya. It is kind of amazing motoring up a steep hill and finding how easy it is to assist by peddling. Gives ya a Superman sort of feeling. (if superman made sounds like a weed whacker, snork)

Really is fun. For ruff ground and off road, try for big tires and suspension if possible. Makes for a much nicer ride.

 

[rsmith]

Thanks for the info guys. It will be used off road, so suspension will be useful. I ride a fully ridgid mtb usually, but I could image that without at least front suspension, the engine would get a bit of a battering. I could see some potential chain tensioning issues with a full sus though. milegajo, your site looks interesting, I may need to visit you at some point. Anyway, thanks, Rob

 

[TigerToothBikes.com]

Thanks for the info guys. It will be used off road, so suspension will be useful. I ride a fully ridgid mtb usually, but I could image that without at least front suspension, the engine would get a bit of a battering. I could see some potential chain tensioning issues with a full sus though. milegajo, your site looks interesting, I may need to visit you at some point. Anyway, thanks, Rob

That'd be good.

From our research a full suspension is the holy grail as almost all in the UK are unsuitable. Front suspension if anything would help the wrists!

 

[rsmith]

What rear sprocket size would you reccomend for off road, but still be able to cruise fairly well on road?
Rob

Btw, the wrists can take it. I rode in the three Peaks cyclocross race this year. A skinny tyred, rigid forked bike race over the mountains. Hurt a little, but at least I've got used to it :¬)

 

[Dan]

Stock ChinaGurl (44T) should be fine I would think. Cruises at around 20 MPH (30 WOT) and is good with hills. But many will have differing thoughts and these are just mine.

 

[rsmith]

Cheers Dan.

 

[TigerToothBikes.com]

I agree with dan, some would suggest a 48/50 tooth for just that extra pulling power at the expense of a coupla miles off the top speed

 

[Andyinchville1]

HI all,

The best gearing would depend on how often the bike is ridden on the trails VS the street and how slow or tight the trails are....

A 50T as mentioned earlier would probably help a bunch on slower trails but not give up too much on the pavement in terms of speed BUT if you plan on lots of trails and slower speeds even lower gearing may be a plus....

To date, the largest sprocket we have made for trail use is a 65T sprocket....I think the largest easily made sprocket (for us) would be about an 80T or so....You wouldn't go fast BUT you could probably go just about anywhere!

Andrew

 

[rsmith]

Some really useful info there guys, thanks. This is going to take a lot of planning as, I have to ask myself the type of trails I'd plan on riding and also whether the engine could take the abuse on extreme trails that would require such low gearing. There are some really steep hills where I plan to ride, but as I say I ride up them on a pedal bike anyway, so the engine will have some help. If I can cruise at say 20mph on road, and get up the hills with assistance then I may try a 44- 50 tooth as you have suggested. The rides will be 1/2 and 1/2 road and off road so I'll have a think, and do some calculations. Thanks again for the advice, Rob. Maybe after this project is completed I will also be able to give some advice too. I sense a steep learning curve ahead.

 

[singlespeeder]

I too live in the hills and am collecting parts to build up a vintage ride, my question is I want to keep the bike looking vintage but would a 1, 3, 7or 8 speed internal rear hub be the answer for pedal assist? I still don't know which engine I will be using, but most likely the 4 stroke honda engine.

Thanks,
Mike

 

[rsmith]

An internal gear hub would certainly look the part on a vintage build, but standard derallier gears would most probably have a wider spread of gear ratios. This would make pedal assistance easier. For low maintenance and good looks though, a gear hub is the best option. My friend has the Shimano Alfine hub and has given it excellent reviews.
Rob