Help! MTB frame criteria for Tongsheng TSDZ2?

[PGT]

Hello All

Just joined this forum and my first posting is a request for help with an ebike build based on the Tongsheng TSDZ2.

After several years of debating I recently took the plunge and purchased a Tongsheng TSDZ2 conversion kit with the intention of fitting it to my existing road bike. Only hours after placing the order I changed my mind when I considered the possibilities of tackling new routes if I fitted the motor to a mountain bike frame.

Now that I have received the motor it appears that a particular constraint in selecting a suitable donor bike or frameset is the splay of the chainstays as they leave the bottom bracket. The motor assembly has a large housing (for the drive from motor to axel I presume) approx 130mm in diameter and15mm thick that could potentially clash with the chainstays or require spacers that would impact on the chainline.

I assume there is a minimum clearance required between the bottom bracket and the outside face of the chainstay, measured in the plane of the end face of the bottom bracket. I have attached an imaged marked-up with two dimensions “A” & “B”.”A” is the key dimension from the axis of the bottom bracket, but difficult to measure. “B” depends on the thickness of the bottom bracket tube but is easier to measure on a bike.

Sorry for the long preamble but I would like to know if my assumptions are correct and if anyone knows what either of these dimensions might be or have any advice on frame selection based on their experiences of a build.

Thanks

Peter

 

[matthewslack]

Hello All

Just joined this forum and my first posting is a request for help with an ebike build based on the Tongsheng TSDZ2.

After several years of debating I recently took the plunge and purchased a Tongsheng TSDZ2 conversion kit with the intention of fitting it to my existing road bike. Only hours after placing the order I changed my mind when I considered the possibilities of tackling new routes if I fitted the motor to a mountain bike frame.

Now that I have received the motor it appears that a particular constraint in selecting a suitable donor bike or frameset is the splay of the chainstays as they leave the bottom bracket. The motor assembly has a large housing (for the drive from motor to axel I presume) approx 130mm in diameter and15mm thick that could potentially clash with the chainstays or require spacers that would impact on the chainline.

I assume there is a minimum clearance required between the bottom bracket and the outside face of the chainstay, measured in the plane of the end face of the bottom bracket. I have attached an imaged marked-up with two dimensions “A” & “B”.”A” is the key dimension from the axis of the bottom bracket, but difficult to measure. “B” depends on the thickness of the bottom bracket tube but is easier to measure on a bike.

Sorry for the long preamble but I would like to know if my assumptions are correct and if anyone knows what either of these dimensions might be or have any advice on frame selection based on their experiences of a build.

Thanks

Peter

This may help.

Could some kindly take some measurements of a tongsheng and bafang mid drive?

I’m building a mid drive ebike as a project with my 14 year old son. I’m concerned that the rear chain stays are quite wide on our frame and may foul on the outer gear housing. I’ve looked at the engineering drawings for tongsheng and bafang units but they don’t show all the measurements and...

www.pedelecs.co.uk

 

[PGT]

This may help.

Could some kindly take some measurements of a tongsheng and bafang mid drive?

I’m building a mid drive ebike as a project with my 14 year old son. I’m concerned that the rear chain stays are quite wide on our frame and may foul on the outer gear housing. I’ve looked at the engineering drawings for tongsheng and bafang units but they don’t show all the measurements and...

www.pedelecs.co.uk

Thanks mr-ed, there is a lot of useful information on that thread particularly the heads-up about the impact of spacers on the non drive side cranks.

The full sized template seems ideal for testing a frameset but I am probably going to purchase a complete bike from a local store where I will only be able to take limited measurements.

As noted on the thread there are many single chainring bikes at the moment which look totally unsuitable (to the point of being limited to a 32T) so I am thinking of choosing a bike with a triple chainring that appear to have much better clearances.

 

[Sturmey]

I fitted one to a hybrid frame and hence no problems. But I do remember looking at a Chinese installation video at that time ( I cant find it now) that showed the installer using a heavy tool and giving a few whacks to 'dimple' the frame at that problem point on the chainstay (which would normally be somewhere behind the chainwheel).

 

[mr_ed]

Mine was a single chain wheel frame and although it took a lot of work (mainly thinking) and I chose the most expensive motor simply because it fit best, now it is all together it is working superbly. I can get all gears with no problems.

you might be able to draw a sort of reverse template that you can hold up against full built frames to check clearance.

 

[mr_ed]

Mine was a single chain wheel frame and although it took a lot of work (mainly thinking) and I chose the most expensive motor simply because it fit best, now it is all together it is working superbly. I can get all gears with no problems.

you might be able to draw a sort of reverse template that you can hold up against full built frames to check clearance.

Althhough I’ve heard that there are no good offset chainrings (like the bling ring) for the tdsz2.

my other bike is a 700c hybrid with a triple chain ring and the tdsz would fit that with no issues at all.

 

[PGT]

I know a “can do” attitude is a given for an ebike conversion but I would like to plan ahead to avoid having to “dimple” a chainstay to make the motor fit. But if all else fails?

I found a Merida Crossway 20 MTB in my local bike shop which has a triple chainring and what looks like a very “hybrid” chainstay geometry so I have asked them to get my size into stock to try out.

The next issue would seem to be re-routing the hydraulic brake hose and rear derailleur cable which on the Merida both exit from the downtube internal routing close to the bottom bracket. Does anyone have any suggestions on that front?

 

[mr_ed]

I know a “can do” attitude is a given for an ebike conversion but I would like to plan ahead to avoid having to “dimple” a chainstay to make the motor fit. But if all else fails?

I found a Merida Crossway 20 MTB in my local bike shop which has a triple chainring and what looks like a very “hybrid” chainstay geometry so I have asked them to get my size into stock to try out.

The next issue would seem to be re-routing the hydraulic brake hose and rear derailleur cable which on the Merida both exit from the downtube internal routing close to the bottom bracket. Does anyone have any suggestions on that front?

Thats a pretty minor issue, can easily route the cables externally or drill a new hole in the frame if need be.