BBS02 on a Road bike with 25c Tires ... Horrible idea????

Looking to build my first commuter ebike. I have searched and researched but can't seem to come up with a solution. I will be commuting 16-18 miles each way in hilly terrain with the biggest climb being 1.60 miles long unsure of grade but very steep for aprox. 0.6miles and then a mile of gradual climbing. I have a nice vintage Nishiki Olympic steel frame road bike with all modern shimano 105 components that I was considering using for this build. The issue is frame will not take anything larger than a 25c tire. I am looking at using the BBS02 at 52v. Is this a terrible idea, i.e. unsafe? Should I look into getting a mountain bike for the build with more tire?
Thank you for any insights in advace.

It will work as long as that bikes bottom bracket is the proper length and not too skinny. With a battery your going to be adding some additional weight so make sure your tires' PSI are adequately inflated before embarking a trip. You'll get ~30mph with it. On smooth roads it's fine. If you ride on crappy roads, switch it up to a bike with larger tires & suspension like a MTB bike.

Make sure your brakes can stop you whatever bike you decide to put it on.

I think it's a great idea. If you can get the battery and stuff streamlined you'll have good efficiency in the drops.

While there's nothing terrible about your plan, there's another option for you to consider.

The recent resurgence of 650B rims was predicated on bikes just like yours; the idea was you can take a good old 1980s bike whose only shortcoming is the skimpy tire capacity, and install slightly smaller wheels with much fatter tires (like 35-40mm) and longer reach brakes, getting the same ride height and geometry in the process.

The same trick would work fine with 650A wheels (26 x 1-3/8"), but tire selection is more limited in that size.

If your existing wheels are "vintage", meaning they have narrow, shallow section rims, you'll do yourself a big favor by replacing them with something more recent that has a deeper section and maybe even offset rear spoke drilling. And in that case, the disincentive to changing wheel size is minimized.

I'm looking at doing something similar but with a BBSHD on a cyclocross bike. My main concern with an older frame like yours is the brakes being rim brakes rather than disks. With the extra speed disks make a huge difference especially if it starts raining.

Are you planning on using a throttle or pedal assist? A throttle is a bit of a bodge to fit to drops. Have a look at my thread a bit down the page

Thank you for your thoughtful replies. @melodious BB length is aprox 70mm with a diameter of 68mm. Could not find any info if this would be to short.

@chalo i considered a wheel swap just concerned that it will lower the bike to much.

@anth_85 I plan to use pedal assist most of the time as I want it to still feel like a bike and not a motor bike. But after a long day fighting Atlanta traffic the added boost is more than welcome. The brakes and complete drivetrain are upgraded from a 2015 bike. Even though they are v brakes it has had no trouble slowing down on big 30+ mph descents. Of course they are nothing like the hydraulic xtr brakes on my trail bike.

I may just go for it and if its to rough or inadequate, I will try to find a more suitable donor and swap everything over.

As for the throttle I do like your version inside the the hood. Very stealthy.

Attached pick of bike in question.

Again thank you for your thoughts.

superl8apex said:

As for the throttle I do like your version inside the the hood. Very stealthy.

Click to expand...

Thanks.

Gorgeous bike. You have 700c wheels on there now. Not sure if the brakes would work with 650b rims?

If you are using BBS02, I'm going to guess, you probably don't want to lower the bottom bracket too much. That depends a bit on what kind of BB drop you have now.

I bought a bike similar to that ('94 lugged chromoly) to electrify. The light steel frame, 8 speed cassette, and down tube shifters seemed like they would work well. I love riding the bike so much as it is, I haven't put a motor on it!

And I have my single speed road bike. Once I added about 15lbs of battery and motor, it just wasn't a great ride. But now batteries are cheaper, and I find with a light weigh 3lb battery it has its road bike personality back. Its my daily commuter.

Comments:
1) you can probably put a small 28mm tire on the rear. I would bet the front fork has even more clearance - 28mm should fit nice up front if no where else.
2) Thud buster is pretty mandatory - unless you really like to ride light.
3) I use my drop bar throttle for top speed only, as I have no problem going 15mph or slower on my own on a road bike.
4) most people here would want lower slacker geometry. I'm going to assume you are happy with this racy geometry. I sure am (I built a longer slacker frame up and only used it a couple of times because it wasn't nimble enough for me).

I think a BBS02 would work well on your bike - especially with 28mm tires. That is what I use. And if it doesn't work out, just get a cyclocross bike from Bikes Direct.
How fast do you go up that hill now?

I have room width wise for 28mm. Just not the extra 31mm circumference for them. With the 25c I have about 1mm from the frame above brakes on rear. 28 on the front no problems at all.

It definitely is a pleasure to ride as is. I normally average 13-16 mph on weekend recreational rides on it. ( After running around on my feet all day pretty sure would not be anywhere near that)

Are there 28mm wide tires available that are same diameter as the 25mm? Because​ problem solved if they do.

I love the geometry of this bike. Heck, I am usually more comfortable on the drops than the hoods.

I was looking at the gravity liberty from bikes direct seems like a nice bike for the money. Don't know if I really need a fourth bike though

I used a nice little Q100 hub motor (2.2kg) to keep the weight down and maintain the feel of the bike. That will get you a light, easy quiet low maintenance 20mph. However, if you need to climb hills and can't keep up ~50% of the motor's cruising speed, you definitely, need the BBS02. And obviously the low center of gravity, extra power and ability to use gears is going to trump the weigh penalty in some cases. I think it is a nice build with a BBS02. There was someone making single and multiple speed bikes a lot like yours commercially a few years ago (Single speed and a mid drive seems like an oxymoron to me).

Tires:

Check this out:
https://docs.google.com/spreadsheets/d/1dyYRfhNdFUIbeF1BiQpMyQnhbepy6nxK9DDgd7BhYSk/edit#gid=0
(don't mess it up, its not mine!)

I have michelin pro4 in 25 and 28mm size - fast and supple and they BOTH measure about 27mm. Same with Continental 4 season - again the 28mm is about 27mm. All three of these fit my Allez which looks to have about the same geometry and clearance as your bike. Conversely, a fat 28mm (Continental 4000S, Thick slick) won't come close to fitting under my rear brakes (they measure about 29mm).

But, if you are 1mm away from the brakes, your only real option to get more volume is a wider rim.

Chalo said:

While there's nothing terrible about your plan, there's another option for you to consider.

The recent resurgence of 650B rims was predicated on bikes just like yours; the idea was you can take a good old 1980s bike whose only shortcoming is the skimpy tire capacity, and install slightly smaller wheels with much fatter tires (like 35-40mm) and longer reach brakes, getting the same ride height and geometry in the process.

The same trick would work fine with 650A wheels (26 x 1-3/8"), but tire selection is more limited in that size.

If your existing wheels are "vintage", meaning they have narrow, shallow section rims, you'll do yourself a big favor by replacing them with something more recent that has a deeper section and maybe even offset rear spoke drilling. And in that case, the disincentive to changing wheel size is minimized.

Click to expand...

If you've got the budget, I'd second this.

What's wrong with the thin tires, exactly?

flat tire said:

What's wrong with the thin tires, exactly?

Click to expand...

They're more vulnerable to damage, punctures, loss of traction, and subsequent damage to wheels, as compared to wider tires. This characteristic becomes more critical when you add substantial amounts of unsprung weight in the form of motor and batteries.

chas58 said:

I used a nice little Q100 hub motor (2.2kg) to keep the weight down and maintain the feel of the bike. That will get you a light, easy quiet low maintenance 20mph. However, if you need to climb hills and can't keep up ~50% of the motor's cruising speed, you definitely, need the BBS02. And obviously the low center of gravity, extra power and ability to use gears is going to trump the weigh penalty in some cases. I think it is a nice build with a BBS02. There was someone making single and multiple speed bikes a lot like yours commercially a few years ago (Single speed and a mid drive seems like an oxymoron to me).

Tires:

Check this out:
https://docs.google.com/spreadsheets/d/1dyYRfhNdFUIbeF1BiQpMyQnhbepy6nxK9DDgd7BhYSk/edit#gid=0
(don't mess it up, its not mine!)

I have michelin pro4 in 25 and 28mm size - fast and supple and they BOTH measure about 27mm. Same with Continental 4 season - again the 28mm is about 27mm. All three of these fit my Allez which looks to have about the same geometry and clearance as your bike. Conversely, a fat 28mm (Continental 4000S, Thick slick) won't come close to fitting under my rear brakes (they measure about 29mm).

But, if you are 1mm away from the brakes, your only real option to get more volume is a wider rim.

Click to expand...

Thank for sharing, my issue is as the tire get wider it also has a larger diameter due to aspect ratio. My clearance problem is the frame above rear tire. I agree on the singlespeed mid drive the whole point was to use the rear cassette gearing.

E-geezer said:

Chalo said:

While there's nothing terrible about your plan, there's another option for you to consider.

The recent resurgence of 650B rims was predicated on bikes just like yours; the idea was you can take a good old 1980s bike whose only shortcoming is the skimpy tire capacity, and install slightly smaller wheels with much fatter tires (like 35-40mm) and longer reach brakes, getting the same ride height and geometry in the process.

The same trick would work fine with 650A wheels (26 x 1-3/8"), but tire selection is more limited in that size.

If your existing wheels are "vintage", meaning they have narrow, shallow section rims, you'll do yourself a big favor by replacing them with something more recent that has a deeper section and maybe even offset rear spoke drilling. And in that case, the disincentive to changing wheel size is minimized.

Click to expand...

If you've got the budget, I'd second this.

Click to expand...

I am not opposed to going 650b wheels, seems it will be my only option to go wider. I have a been hard time finding 650b wheelsets for v brakes. These are the only ones I could find that didn't cost more than getting another bike bike to convert.
http://www.ebay.com/itm/BIKE-650B-WHEELSET-RIM-BRAKE-27-5-SLVR-130-MM-HUB-8-10-SPD-WEI-ZAC19-36-H-/252604585112?_trksid=p2385738.m2548.l4275
Think they will hold up?

superl8apex said:

I am not opposed to going 650b wheels, seems it will be my only option to go wider. I have a been hard time finding 650b wheelsets for v brakes. These are the only ones I could find that didn't cost more than getting another bike bike to convert.

Click to expand...

For that reason, maybe you can also look at 650A wheels, which are usually called 26 x 1-3/8". Those rims are 6mm larger in diameter than 650B, but 32mm smaller than 700c, and the customary tire is 35mm wide. The number of rims and tires available is smaller than 650B, but prices tend to be much lower because it isn't a faddish size.

Well, looks like 650b conversion it is. I just ordered a wheelset that will accept my current 10 speed rear cassette and the appropriate brakes to work with them, for a pretty reasonable price. Haven't decided on tires yet but leaning toward the Marathon plus hs440 27.5x1.5.

Is there a way to calculate how big of a battery I will need to achieve 20-30 mile range on the BBS02?

have a search on the forum for Raged's thread on his. He has a cyclocross bike with a BBS02 on it...

How are rim brakes going to work with the smaller diameter?

What did you order?

chas58 said:

How are rim brakes going to work with the smaller diameter?

Click to expand...

There are caliper brakes in a wide range of different reach lengths. The original bike uses the kind with 39-49mm reach, but now the OP needs the kind with 47-57mm reach.

If he switches from the older single pivot style of caliper brake to the up-to-date dual pivot style, his braking power should be improved.

Might check Rivendell for good quality, long reach brakes, but they'll be pretty expensive.

chas58 said:

How are rim brakes going to work with the smaller diameter?

What did you order?

Click to expand...

Brakes are Long reach tektro r556. I will post pictures when items arrive.

Here is a mid-nineties roadbike I set up with 26" (559) rims a decade ago, as an allrounder. It is my favorite upright. I can actual get a foot down without a rupture, since the bottom bracket is low. You do have to keep the inside pedal up in a tight turn. But that is good advice anyway. It is funny: Back then 650b was as rare as hen's teeth in the US, and 26" was everywhere. Now the fad has switched. The tires are 38 mm.

Got the 650b wheels and new brake calipers
This is the 650b wheel with short tektro caliper for the 700c wheels.



650b wheel with the long reach caliper.



plenty of clearance to run 650x38b tires (which should be pretty much the same diameter of the 700x25c tires)

About to pull the trigger on the BBS02 kit with a 52v 13.5aH battery, any thoughts on which chainring 46 vs 48 tooth. Rear cassette will be 11-34 10speed.

This will be a great setup. Unless it is already set up with a ten speed drivetrain, I would forget the 10 speed cassette. Eight speed components are cheaper, stronger, and you will be shifting two gears at a go with that much power.

I have good luck with kool-stop pads.

Just an FYI, the pads are mounted left/right reversed, or that unit should be mounted as the rear brake. The braking force is supposed to push the pad towards the closed end of the metal pad holder..