tlen

Hi all - I'm new to Bike Forums and joined in hopes of getting some expert technical input.

As a crazed project, I'm modifying a Mongoose Dolomite ($200, 50# Walmart fat-tire bike) to cruise around with my daughter as she learns to ride a bike. Yes it's a steel tube joke, but it's a perfect base to start playing with. My goal is to turn it into a fat tire-stingray-rat bike...

I'm looking to upgrade its stock Shimano 14-28t Tourney TX 7-speed (SIS Index) freewheel and it's accompanying derailleur/shifter mechanisms. After looking around, I've become partial to SRAM's X9 system (X9 Exact Actuation Trigger Shifter, X9 Rear Deraileur, and the PG-1070 10-speed freewheel cassette). My question is if the SRAM cassette is compatible with my hub (that fits the Shimano freewheel)?

I'm (currently) not looking to add a multi-sprocket crankset, so I'm only worried about the freewheel's thread size as well as the cassette's width. I've scoured the internet and not been able to find these dimensions. I'm presuming they are both standardized (as there are no specs readily available), but I wanted to be sure before I drop a couple hundred bucks on the parts.

Thanks in advance for any input you might be able to share!

Senrab62 

Look up "the dolo in the semi wild" + mongoose - in Google. It's a multi page thread on the bike on another forum. I bought one for cheap a couple holidays ago, but found it too heavy. That thread is FULL of info regarding the dolomite and similar models.

Nice to see you encouraging riding with the fam! Good luck.

fietsbob

Hub to freewheel thread is British standard for all of Asian made bikes..

Its the overwhelming world wide favorite.

A cassette is not a freewheel , the conversion costs more than you paid for the bike, so .

It's Time to go to a bike shop and buy a New Bike. put yours in a Garage sale in the spring/summer.

Or just buy another 7 speed freewheel..



...

ramzilla

Cassettes and freewheels are completely different animals. Sram threaded freewheels & shifters are directly compatible with Shimano threaded freewheels, spacing & shifting. I've had success lately with long cage Shimano Deore RD's & 7 speed extended range threaded freewheels. I've found a source on ebay where I can pick up the Deore RD's brand new for $30.

Retro Grouch 

That's going to be a fairly pricey upgrade. Shifter, rear wheel, cassette, derailleur (and a claw hanger mount).

dabac

As stated, freehubs and freewheels are different things. You won't be able to use the cassette you've listed w/o lacing in a new hub.
There are 10-speed freewheels (Sunrace for instance). But they leave a considerable amount of unsupported axle, which can cause issues later on.

CliffordK

I've got a slightly modified Mongoose Massif.




A couple of things that I've discovered in the process.

The derailleur hanger, while flimsy, is "standard", and can be used with other derailleurs.

As mentioned above, the hub has a freewheel, and not a cassette. With the small wheels, I need the higher gearing. Right now, I'm using a 7 (or 8?) speed DNP Epoch freewheel, giving me 11-28 gearing. There are ones that give a wider range too. DNP also makes 9 and 10 speed freewheels. I suppose that if an 8 can be more or less used, then a 10 should be fine too, a the width should be similar. Do you really need all those gears? My rear dropouts did get tweeked a bit, so I don't remember what the originals were like.

I have problems with my rear derailleur cage dragging on the rim, which you probably won't have to deal with on the Dolomite. The chain also drags on tire a bit in the lowest gear, perhaps due to the triple chainring configuration.

I'm also shifting with a single traditional friction stem shifter.

I never got the front derailleur connected yet as standard derailleurs don't fit well with the extra wide bottom bracket, and don't reach out far enough to get to the cranksets. I assume "FAT" bikes have resolved the problem. At some point, I'll make a custom front derailleur mount. For now, I do what is known as "greasy finger shifting". It will sometimes just drop from the top ring to the middle ring.

Oh, also note, everything in the Massif was made as cheaply and crudely as possible. I think even the rear bearing races were PAINTED (which, of course, wore through quickly). As I work on parts, I do like to spin polish/sand the bearing cones.

tlen

Hi all -- wow! Thanks for all the input -- very cool!

I've learned something new today -- that there are freehubs that use cassettes and there are freewheel hubs that use threads. I presumed the cassette was the gear cluster that would thread onto the freewheel hub. Now I know better. Thanks!

I appreciate all of your patience with my ignorance. As my wife says, I know just enough to be dangerous...

Yes, the Dolomite is a POS, but as I've not ridden for a few too many decades and I don't need anything fancy keep up with my daughter. The frame is a perfect cheap base to work from. Yes, my various upgrades are worth more than the bike, but it all aligns with the goal of just having some fun. I'm not going as far as CliffordK's mods (that thing is crazy!), but I'm having fun. I've got a 26" banana seat that will mount with a old school tall sissy bar and some 18" ape-hanger handlebars. When done it will be hilarious--perfect to cruise around with my daughter. I'll post a picture once done.

No, I don't need that many gears and thanks for the tip about chain clearance issues. I've seen some extender brackets to push the front derailleur out to accommodate the fat tire frame. Again, I'm not looking to add a multi gear crankset so that's not a concern. My goal is to get a wider rage of gears on the back, leaning towards high tooth number so I can easily sit and grind slowly up hills... I'll continue looking at options. I was really impressed with SCRAM's X9 Exact Actuation trigger shifter--so precise and quick. Coupled with the larger gear range (11-36t) seemed a straight forward modification.

I'm good with 7-ish gears, but as noted earlier, I'd like a wider ratio range that goes lower. My other priority is to get a solid shift mechanism. If anyone has any recommendations, I'd appreciate it. Obviously, I'm good to drop a couple hundred on these parts--which I know is more than the bike is worth. This is about having some fun, cruising slowly, but having solid mechanicals.

Thanks again for all the input. I thought I would get a couple odd responses with people laughing at the bike. Instead, I got a lot of fantastic input very quickly. You all are great! Thanks!!!

nfmisso

tlen; a recommendation, based on you liking SRAM.

14-34 freewheel: https://www.amazon.com/Shimano-MF-TZ.../dp/B003RLNOKC the shift to the largest cog is a knee tenderizer.
SRAM 7 speed shifter: https://www.amazon.com/SRAM-X-3-Rear.../dp/B002MQZD1G - NOTE will NOT work with your current RD.
SRAM RD: https://www.amazon.com/SRAM-Rear-Der.../dp/B001FC9HRO

Also get a new chain - I like KMC X8.93 for my 8 speed and less bikes - I purchase the 5 packs.

You will need some tools:
* freewheel remover tool for Shimano.
* chain tool - to remove link.
* metric allen wrenches - 5mm hex need to remove your existing RD.
* cable cutters - to shorten the new shift cable and cut housing.

tlen

Thanks nfmisso! These recommendations look good -- I'll check them out.

The input from this forum is fabulous -- thanks so much!

nfmisso

your welcome; we are all glad to have new members who communicate what they have well.

If you get more ambitious/crazy; you could build up a replacement rear wheel with a freehub-hub.... I build my own wheels after a LBS pissed me off.

tlen

Thanks again for all the fabulous input -- very much appreciate!

I think I'm going to go with the Shimano 7-speed cluster (14-34t) as it's a straight bolt on.
For shifting I'm going with the SRAM X4 8-speed derailleur with a long cage, along with the SRAM SI Gxdh Trigger 7-speed shifter.

I presume I'm good with the 8-speed derailleur with 7 gears as the shifter will prevent over reaching the freewheel cluster. If I'm wrong -- please let me know!!!

BTW--many thanks to nfmisso for the recommendations!

I've not done any research on what chain length I need... More to learn!

If nobody sees any issues with this combination, my final challenge is to find a rear fender that fits... I can do a lot of fabrication, but rolling out a fender is beyond my skill (and tool) sets.... I've been looking at motorcycle parts fabricators (as what's available for fat tire bikes is slim pickings...), but this bike's tire dimensions (radius=14.5" x 4 2/3" width) are totally not common. Weeee!!!!

Thanks again for all the great input. I'm looking forward to getting this crazed thing assembled. I'll post pics once done!

Homebrew01

Not sure if that will work or not.
Indexed systems are very picky. The shifter pulls a specific amount of cable with each "click". And the geometry of the rear derailleur needs to match, so that it moves the correct amount, to also match the cassette cog spacing.

Once you start inter-mixing different "speeds" (7, 8, 9...) you are likely to get mismatches in cable pull.

Some combinations will still work, others won't.

Also, even within the same "speed" some road groups do not match with mtn bike groups, so you may not be able to mix mtb shifters with road derailleur even if they are all the same "speed".

ramzilla

The shifter determines the distance the RD travels. A 7 speed indexed shifter connected to an 8 or 9 speed RD will properly index shift through all 7 cogs. No worries. I use 7 speed extended range freewheels with 7 speed indexed trigger shifters with Deore M591 (9 speed) rear derailleurs often.

tlen

Continued thanks for all the input! I've ordered the parts and am looking forward to assembling.

Does anyone have any experience with Rad Power Bikes' Radrover Full Fenders? I'm not keen on plastic fenders but I can't find much that will fit. There are some beautiful wood fenders, but they don't align with the aesthetic I'm after. Rolled aluminum with a bit of a flare on the end is what I've been looking for, but I can't find any made to the tire size.

Thanks again for all the fabulous input!

Bike Gremlin

Wrote a lot about various components compatibility:

Compatibility Archives - Cycle Gremlin

For SRAM, 8 speed RD will work with 7 speed shifter if they are the same type - both "1:1" (since that RD is 1:1 I believe).

Here's one way to determine a proper chain length:
Chain length sizing for bicycles with derailleurs

u235

Agree I use a Deore M591 with a SRAM X 8 speed Gripshift (Shimano pull compatible) and swap between two different wheels sets all the time
One with a Shimano 14-34 7 speed "megarange" freewheel and another with a SRAM 850 8 speed 11-32 cassette. A simple turn or two of of the barrel on the RD and adjust the high stop and I'm done. This is not the only combination that worked for me, I had at least one other RD on there before (a cheap long cage Tourney), different 7 speed freewheels, and different 8 speed cassettes at one time or another.

When the 7 speed cassette is on, the 8th gear position on the shifter does nothing.