Woosh Big Bear Chainring.

[garyten]

Im new to bike's and pedelec's, having been on motorcycle's for 30 years, so i need a bit of advice please.

I recently bought a Big Bear, and i noticed that it tops out (i cant pedal any faster) at about 21 mph in 7th (top) gear. I would like perhaps another 2 or 3 mph, for the downhill bits.

I then remember reading here, that i may be able to change the Chainring to something larger, so here is the problem.

The standard chainring is a 5 bolt 44 tooth, so i decided to try and find a alternative, so i begin with a E mail to Woosh, and they replied saying that " You can install any chainset and gearset you like. They are Shimano standard".

I dont know what Shimano standard is, so i measured the BCD with my vernier caliper, and i end up with 49 mm. Using Sheldon Browns excellent website im translating to a BCD of almost 84, which appears nonsense.

Short of taking the Chainring of the bike, and going to a shop, im calling on you nice lot, if you know what Chainring is fitted to the Woosh Big Bear, or can you tell me how to find out, as im at a loss, despite my motorcycle engineering knowledge, the Cycle industry is a whole new learning curve.

Thanks for any advise.

 

[trex]

you'll need a 52T or 54T crankset, new chainguard, new chain.
it's easier to change the freewheel for a 7-speed 11T DNP.
http://www.universalcycles.com/shopping/product_details.php?id=49866

 

[JohnCade]

trex this place you're linking to is in the US. I'm out of touch with bike stuff nowadays so where's the best value place to buy parts online now?

 

[trex]

cyclezee may have 11T DNP freewheels. Your bike has 8-speed 11-32 cassette like mine, last time I paid £10, from ChainReactionCycle. I buy bike parts from CRC, tools from amazon, the rest from ebay.

 

[RobF]

Does the big cog on the new cassette have the same number of teeth?

If not, you will also get a higher first gear, which may, or may not, be a problem for you.

 

[garyten]

Thanks for the advise, that sounds like a good idea. i didn't realise that other brands of freewheel would fit.

Just out of interest, does anyone how will i find out what my Chainring is, apart from taking it to shop, Ive tried measuring the BCD, and got 49 mm between the centre's.

Woosh have told me " You can install any chainset and gearset you like. They are Shimano standard" i dont understand what "standard" is. as i would just like to know if i have a very unusual size.

thanks again.

 

[trex]

the crankset on the Big Bear is a typical Chinese 44T chainring and 170mm alloy cranks for square tapered spindle. Something like this:

suitable 52T cranksets:
http://www.ebay.co.uk/itm/Lasco-Alloy-Crank-170-mm-x-52T-Crankset-/130957470204

 

[Deleted member 4366]

John's out of stock of those free-wheels, so you'd have to get one from Germany:
http://www.ebike-solutions.de/de/Shop/Motoren/Schraubkraenze/Schraubkraenze-mit-7-Ritzeln

You'll need their removal tool too:
http://www.ebike-solutions.de/de/Shop/Fahrradzubehoer/Montagewerkzeug/Abzieher-fuer-Schraubkraenze

If it were my bike, I's be looking through Ebay and the local car boot sales for a cassette rear wheel. Then you can get your cassette from anywhere. If you're lucky, there might be one already on the wheel.

Here's a new one:
http://www.ebay.co.uk/itm/WEINMANN-XPLORER-REAR-26-MTB-BIKE-WHEELS-QUANDO-Q-R-7-8-9-10-Spd-CASSETTE-BLACK-/171380141691?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item27e70d6e7b

http://www.ebay.co.uk/itm/BANKRUPT-26-REAR-CASSETTE-7-8-9-SPEED-WHEEL-MOUNTAIN-BIKE-CYCLE-Q-R-CHEAP-NEW-/380888243892?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item58aeb55eb4

For those that need a disc brake one:
http://www.ebay.co.uk/itm/26-REAR-DISC-BRAKE-Mountain-Bike-Wheel-D-WALL-BLACK-8-9-Speed-Cassette-/231197046410?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item35d46af68a

 

[garyten]

Thanks guys, a wealth of information, and a big thanks for the links, a lot of food for thought.

So if i needed to replace my Chainring, i just need to ask for a standard 44t Chinese type ?

 

[Deleted member 4366]

If you're going to get a new crankset, get a Shimano M590 Hollowtech one with 48T. You can still upgrade to a rear cassette wheel later if you want.. These cranks go as low as £50, but make sure its 48T, not 44T, which is more common:
http://www.pedelecs.co.uk/forum/threads/upgrade-your-cranks-for-£66-or-less.15682/

http://www.ebay.co.uk/itm/Shimano-Deore-FCM590-3x9-Speed-48T-Crank-Chainrings-BB51-Bottom-Bracket-/310910732611?pt=UK_sportsleisure_cycling_bikeparts_SR&var=&hash=item4863b94943

Note: If you get a bigger crank, you have to chuck your nice chain-guard. A new rear wheel is a lot easier. In fact you only need the hub if you know how to build a wheel.

 

[garyten]

Thanks d8veh, i like Shimano M590 Hollowtech idea.

I have no idea how to build a wheel. but like everything, i can always learn.

Can i ask, why the Shimano M590 Hollowtech, is better?

The Chainring i have now, has no branding on it, unlike the rest of the parts on the bike, and given i cant find what size it is, would converting to the Shimano make it easier to replace the chainring.

 

[Woosh]

Hello Garyten,

We have a used 48T ring and crank (just the chain side) that I can let you have cheap - from October, we should have stock of 52T cranksets for the Big Bear and Big Bear LS.

Hatti

 

[RobF]

Hollowtechs are deemed to be the best bottom brackets for performance and reliability.

However, the frame will need to faced - engineering job - because if you fit a Hollowtech to a frame with slightly out of true faces, the bracket will run askew and not last long.

A competent bike shop can face the frame for not much money.

Bear in mind if you just change the chainring, you will get a higher bottom gear as well as a higher top one.

 

[Deleted member 4366]

Hollowtechs are deemed to be the best bottom brackets for performance and reliability.

However, the frame will need to faced - engineering job - because if you fit a Hollowtech to a frame with slightly out of true faces, the bracket will run askew and not last long.

A competent bike shop can face the frame for not much money.

Bear in mind if you just change the chainring, you will get a higher bottom gear as well as a higher top one.

What????
Where did you get that from? The bearing holders line up on the threads in the BB, which are co-axial. Where does the frame come in to it? There's nothing you can change on the frame to change the alignment of the threads!
I've switched six of my cranks over to hollowtech, and they all work perfectly.

Hollowtechs are better because they're lighter, stiffer and easier to service. No creaking like you get on Octalink type ones and the cranks don't come loose and leave you stranded like on a square taper type. Basically, everything about them is better. I haven't found any disadvantages. Fitting a pedal sensor is also pretty straight forward.

 

[RobF]

What????
Where did you get that from? The bearing holders line up on the threads in the BB, which are co-axial. Where does the frame come in to it? There's nothing you can change on the frame to change the alignment of the threads!
I've switched six of my cranks over to hollowtech, and they all work perfectly.

Hollowtechs are better because they're lighter, stiffer and easier to service. No creaking like you get on Octalink type ones and the cranks don't come loose and leave you stranded like on a square taper type. Basically, everything about them is better. I haven't found any disadvantages. Fitting a pedal sensor is also pretty straight forward.

Two trained bike mechanics and lots of stuff on the web.

Yes, you can fit an external bottom bracket without facing the frame and it will work for a time.

But because the bearings rely on the frame faces being absolutely parallel to run true, if they are not there will be accelerated wear.

Top quality frame makers supply their frames 'faced' for this reason.

It all comes down to how properly you want to do the job.

http://forums.mtbr.com/bike-frame-discussion/bottom-bracket-facing-hollowtech-cranks-601704.html

 

[garyten]

Just to Clarify for myself, what size (BSD) of Chainring fits the Big Bear, as if i wanted to buy a standard replacement one

I just like to know the actual size of the Chainring in terms of the 5 bolts. Or do i have to buy it with the crankset attached.

 

[Deleted member 4366]

Two trained bike mechanics and lots of stuff on the web.

Yes, you can fit an external bottom bracket without facing the frame and it will work for a time.

But because the bearings rely on the frame faces being absolutely parallel to run true, if they are not there will be accelerated wear.

Top quality frame makers supply their frames 'faced' for this reason.

It all comes down to how properly you want to do the job.

http://forums.mtbr.com/bike-frame-discussion/bottom-bracket-facing-hollowtech-cranks-601704.html

Complete baloney as far as normal cycling is concerned. There's a plastic spacer behind the bearing holder that will take up any small misalignment, and these parts won't distort when you tighten them unless you go nuts with the special tool. You only need to nip them up.

Even if the bearings did wear out prematurely after a few years, they only cost about £10 a pair and take about ten minutes to fit.

 

[trex]

Just to Clarify for myself, what size (BSD) of Chainring fits the Big Bear, as if i wanted to buy a standard replacement one

I just like to know the actual size of the Chainring in terms of the 5 bolts. Or do i have to buy it with the crankset attached.

you mean BCD (bolt circle diameter) - the Big Bear chainring does not have bolt circle - you need to replace the crankset, you can't swap out just the ring.
As d8veh said, if you look at a long term setup, the 48T hollowtech crankset at £50 is excellent VFM but 48T won't give you much, only up 2mph. A 52T chainring gives about 4mph but you have to wait for Woosh to bring them in. The DNP freewheel gives also about 4mph, is the cheapest and easiest solution.

 

[garyten]

Thank you trex, for explaining that for me, i was getting a little confused.

If i can ask about the Hollowtech cranksets, they are all triple chainrings , what do i do with to 2 extra chainrings?

I think i need to get over to youtube, and learn a bit more about cycle mechanics, as don't really understand a lot about bottom brackets and cranksets etc.

I got this reply from Woosh, "The bottom bracket is cartridge with square spindle. If you want to change to Hollotech or Isis, you may need to change the pedelec sensor (£10)"

Also thanks to Hatti, i may also get a 52t in October, if i still feel the same about the 44t.

It appears I still need to learn more, i thought i knew a bit of bicycle mechanics, but there are far more options than i could imagine.

Thank you all for kind help, and i now feel a bit more "enlightened".

 

[trex]

...
I got this reply from Woosh, "The bottom bracket is cartridge with square spindle. If you want to change to Hollotech or Isis, you may need to change the pedelec sensor (£10)"
...
.

this is the kind of bottom bracket (BB) fitted in your Big Bear:
Shimano UN55:

This is a BB for Hollowtech:
Shimano 4600

The bearing cartridges are inside the BB shell in the Big Bear, they are outside the BB shell in the Hollowtech.
Woosh advice is not totally correct. Although you can't refit the pedelec sensor that fits the UN55 with the Hollowtech like it is, d8veh has posted a thread how to reshape the metal ring of the pedelec sensor and how to fit it to the 4600. If you follow his method, you don't need to spend £10 on a new sensor but you may need to get a dremel to reshape the part.
If you want to go the Hollowtech way (long term best solution) then install new front and rear shifters and new derailleur to your bike and have 3 x 9 sp or unscrew and lose two smaller rings and keep the 14-34T 7-speed Shimano freewheel.
As I said before, replacing the 14-34T 7-speed freewheel with 11-32T 7-speed DNP is the quickest (10 minutes top), simplest and cheapest.