Thoughts on converting Giant Road e+1 to 1x drivetrain

[Gubbins]

I get the feeling that this might be easy to try but I am probably/usually wrong! Is it a case of just buying a cheapo 40T(ish) ring and sticking it on to try, or is it more involved than that?
I dropped the chain again today, just setting off as I had forgotton to drop to the small ring as I came home last time so did it carefully on the way up the hill and it instantly jammed up with a few more gouges on the stay.. I usually ride in the big ring all the time and only use the small one for the bigger hills and shifting up/down usually involves a double shift as the gears overlap which can be a pain, so feel a compromise in in there somewhere
As I see it there are three things to consider.. Gearing.. (getting high/low right), chainline and making the parts fit.
Currently running 50/34 x 11/32 x 11 and the higher gears are far too high with 40 mph achievable at around 90 rpms on the 50T and the lower gears being absolutely fine on the 34T, so, as I never go anywhere near 40mph (even downhill) the top two at least arent needed and although I rarely use 34-36 its handy for a rest on long climbs so not sure if I want to lose it.
There is plenty on line about single drivetrains but they are he-men on featherweight bikes, not an old man on an e-bike (sorry, Pedelec).
Has anyone tried anything like this? (edited cassette)

 

[Fat Rat]

A lot of ebikes run single speed Bosch is an obvious one
I run 11-42 and 16t front which works out at 40t standard and there’s nothing I can’t climb and has a good top speed down hill 36mph ish without spinning out

So it can be done easy

I should add I use 27.5 x 2.8” tyres

 

[Gubbins]

A lot of ebikes run single speed obviously Bosch is an obvious one
I run 11-42 and 16t front which works out at 40t standard and there’s nothing I can’t climb and has a good top speed down hill 36mph ish without spinning out
So it can be done easy

To change to 11-42 would probably need a new gear changer. But.. how easy is it to fit a 40t on the front?

 

[Gubbins]

That's the rear sorted.. what about the front?

 

[anotherkiwi]

I run a 42 on the front and it is a little under geared for me (700C with 2" Big Ben tyres) a 44 would be more suited. I do think that for round town use a 38 wold be perfect - range of speeds at cadence from 13 to 42 km/h

 

[grazie]

To change to 11-42 would probably need a new gear changer. But.. how easy is it to fit a 40t on the front?

Not sure what chainset your bike uses, but most have allen key bolts on each chainset arm to hold the two chain rings in place. You need to take the chain off the chain ring and loosen all the bolts. If you lucky none of them will spin which prevents loosening off the bolt. Once loosened you'll need to hold the nut behind the chainset to fully loosen, but I'm not sure you how much room you have with motor in such close proximity. If you can get all the bolts off remove the outer chain ring and replace it with the smaller one. However the inner chain ring may fall off once the bolts have been removed. Personally I think going to 40T would be too far. With 40/34T more than half of your gears will overlap. Perhaps 42T or 44T would be better? We're all different though.

If any of the bolts spin or you can't 'hold' the nuts at the back of the chainset, you'll need to take the chainset off the bike. How you do this possibly depends on the chainset/motor combination you have.

 

[Artstu]

If any of the bolts spin or you can't 'hold' the nuts at the back of the chainset, you'll need to take the chainset off the bike.

usually possible without, especially with the right tools, although removing it isn't difficult either

 

[Gubbins]

usually possible without, especially with the right tools, although removing it isn't difficult either

Wasn't meaning how to actually undo the bolts, I was thinking more of the chain line and whether to mount it inside or outside.
Was hoping someone had already done it on one of their analogue bikes.

 

[Artstu]

Wasn't meaning how to actually undo the bolts, I was thinking more of the chain line and whether to mount it inside or outside.
Was hoping someone had already done it on one of their analogue bikes.

Sorry yes I realise that, my post was in answer to grazie's.

I'd say outside, if I remember correctly you don't have much room for a bigger inner chain-ring.

 

[Gubbins]

Sorry yes I realise that, my post was in answer to grazie's.

I'd say outside, if I remember correctly you don't have much room for a bigger inner chain-ring.

Om rings are custom with a slight offset 2hich might great problems. Might take em off and go see what LBS says. Looks like I can can get a narrow/wide 42t reasonably cheap to try. Just don't know if an 11-36 will fit . Currently has 11-32.

 

[Nealh]

To go larger then 11/32 on the rear you need to say what mech you currently are using as they usually have a max low tooth rating, road bikes will have a short or med cage.

To go 11/36 or even 11/42 a road link can be used and extends the mech 20/22 mm lower to enable (jockey wheel clearance) and the jump to a larger low gear and often no need to make any mech screw adjustments
SJS Cycles sell a copy road link for about £4.

My gravel bike came with a 11/32 and a Tiagra GS cage, a road link enabled me to go 11/40 with a Sunrace cassette.

 

[Gubbins]

To go larger then 11/32 on the rear you need to say what mech you currently are using as they usually have a max low tooth rating, road bikes will have a short or med cage.

To go 11/36 or even 11/42 a road link can be used and extends the mech 20/22 mm lower to enable (jockey wheel clearance) and the jump to a larger low gear ultegra often no need to make any mech screw adjustments
SJS Cycles sell a copy road link for about £4.

My gravel bike came with a 11/32 and a Tiagra GS cage, a road link enabled me to go 11/40 with a Sunrace cassette.

Looks like I am nearly there.. I think the gears are 101 Shimano whatever that means..
Edit..... 105 front ultegra rear

 

[Nealh]

Ultegra is 105 group set, rear mech will be a medium GS cage might just manage a 36t low gear but nothing larger without a road link.

 

[Gubbins]

Ultegra is 105 group set, rear mech will be a medium GS cage might just manage a 36t low gear but nothing larger without a road link.

I spent an hour going through all the gear inch tables without much success until I figured it out. Unless I am wrong it is simple math. Devide the front ring by the rear to get a ratio and it appears that a 42/36 is about the same as my second gear and 42/11 is near enough my eighth so should work.

 

[Nealh]

The spec for 105 GS cage is max rear low sprocket is 32t, max front chain wheel 16t different .
Max total capacity shouldn't exceed 37t front to rear.

If the rear mech changes up to the 36t ok you should be ok with mech capacity as 11/36 x 42 only works out as 31t total capacity.

The only issue arising using 11/36 with 105 GS cage is over straining the mech as it may or may not fail at some stage, using a road link will prevent the extra strain.

36t is beyond Shimano's 32t max recommended sprocket size, but have seen utubers successfully managing it. Though how it performs long term reliability wise know one say's or mentions.

 

[anotherkiwi]

I bought an entry level spec trike and the entry level Shimano derailleur (rear) handles an 11-40. It was a real pain in the rear to set up correctly and I am still not 100% happy with it. 10 speed is in my very near future (I have had some good news...) and I will use the DEORE RD-M6000 GS Shadow+

I have been thinking of using the stock 46 tooth chainwheel that came with the GSM and a Sunrace 11-46 cassette. I know the 46:46 will climb anything, the motor stalled with 46:32 on very extreme gradients. And 46:11, if I can spin it, is 60 km/h at cadence. Anything faster downhill is grin and hold on tight, no pedalling at the moment, so I think I can live with that top speed.

The twin chainwheel choice would be 48-32 and the cassette the Shimano 11-42. Some very serious tampering and parts fabrication will be required to get a Sora front derailleur to reach out to the outer chainring on the GSM...

 

[Nealh]

Some Shimano road bike group sets are fairly compatible with MTB group sets, though not all. If ever mixing the two you have do thoroughly do your home work via forums etc, to ascertain which might work.

10sp Tiagra appears to not be compatible.

 

[Gubbins]

Going by youtube research and comments posted the way forward is to change as little as possible which would be a narrow/wide chainring, wider range cassette and a hanger adapter, all of which are within my skills to fit.. I think!
Today I am going to try running all 11 gears on the big ring to look for possible shifting problems at the lower end, and a visit to all terrain at Shipley to see if my custom ring has any sort of offset to a std ring which may help or hinder getting the right chainline.

 

[georgehenry]

Although I run a single chain ring set up on my Yamaha PU Haibike and have found by a little experimentation the perfect gearing for my own journeys that include off road and road riding and therefore need a pretty wide spread, I can see your double chain set up as also very good for road riding and would not worry if the upper gears are unused as it means that at the fastest pace you manage to maintain on the road you are using a cog in the rear cassette with more teeth and as a result more resistant to wear, I would be happy with that. Those of us that attempt to put more power through the smaller cogs on our rear cassettes for long periods on the road when commuting using crank drives have often found them to prematurely wear out.

 

[Gubbins]

Although I run a single chain ring set up on my Yamaha PU Haibike and have found by a little experimentation the perfect gearing for my own journeys that include off road and road riding and therefore need a pretty wide spread, I can see your double chain set up as also very good for road riding and would not worry if the upper gears are unused as it means that at the fastest pace you manage to maintain on the road you are using a cog in the rear cassette with more teeth and as a result more resistant to wear, I would be happy with that. Those of us that attempt to put more power through the smaller cogs on our rear cassettes for long periods on the road when commuting using crank drives have often found them to prematurely wear out.

The not using small cogs is a secondary consideration.. Primarily its the constant chain jamming and having to change down 2 gears when going up to the big ring..
Plus I am stuck at home, am bored and depressed so need a project to get me into gear so to speak..