Momsen JR100: convert to 1X

[JulienR]

I have a momsen jr100 (24 inch frame from ~2015 eith 26" wheels) and i want to convert it to a 1X

 

It is currwntly a 3x7 speed with Shimano Altus 7 Speed RD and with a 12-32T cassette on a freehub and 3x chainrings up front 42/32/22

 

I am looking to convert to a 1x to simplify the shifting. I was thinking of maybe a 11-36T in the back and a 32T in the front.

 

- has anyone done this before?

- what speed cassette can i fit on this hub? It measures 31mm from the end of the freehub to the step (see pics)

- the front crank takes a 4 bolt but i am not sure what bcd it is?

[ChrisF]

Julien YES it can be done 

 

https://community.bikehub.co.za/topic/181779-mongoose-rebuild-project/?hl=mongoose

 

 

 

 

your biggest challenge at the moment is the stupid parts shortage ....

[JulienR]

Thanks Chris, a very detailed and interesting build!

I suppose the starting point for me is to understand what size / speed cassette can fit on my freehub. I see there are some 9 and 10 speed cassette options which have some larger range

 

Does anyone know if a 8 or 9 speed cassette can fit on the 7 speed freehub?

[dasilvarsa]

Thanks Chris, a very detailed and interesting build!

I suppose the starting point for me is to understand what size / speed cassette can fit on my freehub. I see there are some 9 and 10 speed cassette options which have some larger range

 

Does anyone know if a 8 or 9 speed cassette can fit on the 7 speed freehub?

Why not Stick to the current cassette and Run a 30 tooth up front instead of the 32.

 

If I remember correctly you can put a 7 Speed Cassette on a 8 Speed Freehub but Not the Other Way Around.

Edited April 10, 2021 by dasilvarsa

[ChrisF]

Julien post a photo of the cassette.

 

Most probably the standard freehub used for decades.

 

When we did the Mongoose 11 speed was the widest range that would fit on it. Now the Sram NS 12 speed fits on the standard freehub.

 

 

Just make sure of the range you want from the cassette, ie 11-32 or 11-42 ... for wide range cassettes you need a different derailure.

[ChrisF]

Something else to consider ...

 

Up to 10 speed you can use a standard front ring. From 11 speed you need a narrow-wide front ring.

[JulienR]

See pics of the freehub. I can post pics of the cassette if needed

[JulienR]

See pics of the freehub. I can post pics of the cassette if needed

[JulienR]

It measures 31mm from the end of the freehub to the step (see pics)

[BMXER]

Your gear ratio may be a challenge.

Who will be riding the bike?

 

Age / skills have a role to play when setting up a ratio for a young cyclist.

Edited April 11, 2021 by BMXER

[Barry]

The JSL, JL and JR if like the Titan 249R should be a X-Small/XX Small 26er.

find a good second hand set of 26er wheels and a nice fork and you can pimp the bike out full XT 10 Speed with Hydraulic brakes.

Done a few using NOS Raleigh RM5 bikes as a doner.

Edited April 11, 2021 by Barry

[Heinrichgg]

My research suggests that a 31mm body length only fets 7 speed. 35mm necessary for a 10spd cassette. A quick google can help you confirm or if you have a cassette with more sprockets lying around, try to fit it and see.

 

I recently did a 1x conversion that cost me just under R3k with all new parts. Deore rdm5120 derailleur, deore csm4100 11-46 cassette, kmc 10spd chain from evobikes and then a rapide n/w 34t chainring. I should probably have gone with a 30t but live and learn. I already had a shifter as it was a 2x10 before. I ised rapide's 2mm spacers to improve my chainline but for a triple crank you can get a good chainline by mounting on the middle ring. If I'm correct and the 1x conversion wont work with your current hub, the costs start to not make a lot of sense for the value of the bike to start off with.

[JulienR]

Thanks for the advice. Sounds like i should look for a set of 26er wheels and then i can go 10 speed.

 

Now to find some parts.

 

Thanks

[dasilvarsa]

Thanks for the advice. Sounds like i should look for a set of 26er wheels and then i can go 10 speed.

 

Now to find some parts.

 

Thanks

Make Sure the Wheel you buy is correctly dished for 10 Speed and is compatible to your frame.

[Barry]

Nice 26er wheels often pop up on the hub.

Need to be 8 speed minium as 8 speed freehub will work for 8/9/10 speed.

Can even go 11 or 12 if you go with Sunrace cassette

Edited April 11, 2021 by Barry