Tweaking on my S40 done - for now!

[Greg S]

Over the past several months I've made a number of changes to my S40 and I thought I'd share a few of them here. To recap the changes I've posted previously:

• I changed from the standard 17" chain stay to the 19"
• I moved from the 1X drivetrain to a SRAM GRX 11 speed with 50x34 chainrings and 11x40 cassette
• I switched from disc to rim brakes. As part of that switch, I took off the 650b wheels with 38mm tires and installed 700C Enve wheels (SES 4.5 with PowerTap hub front, SES 3.4 rear) with 32mm Continental GP5000's set up tubeless
  
• I installed a Thor Sport seat

I should also note that I had back surgery last August and was cleared to start riding again on 10 October. Since then, I've ridden just under 2000 miles total with 983 on the S40.

Overall, I was very happy with the function of the bike but not with the fit. I just wasn't comfortable and this limited how far I could ride. After 20-30 miles one of my neck, shoulders, butt, calf muscles hurt. Some of this was residual from the surgery (calf muscles specifically) as I also had numbness in my forefoot that would get worse the farther I rode.

So I've been working to resolve all these niggling fit issues and finally after a lot of tweaking I have to say it's now perfect. The biggest change I made was the position of the seat. My initial installation had the holes for the front frame tabs drilled 5.5 CM back from the lip of the seat. This resulted in a fair amount of my butt hanging off the front of the seat and the angle was such that I felt like I was sliding off.

I moved the seat considerably farther forward, the holes are now a little under 11 CM back from the lip. This made a huge difference - I'm now fully on the seat, it angles up slightly so there's no sensation of sliding off.

As part of moving the seat forward, I used the moldable thermoplastic that @tiltmaniac documented so well here. I made a shim only for the front of the seat, it's approximately 3 CM thick and covers both of the frame tabs. You can just see it in the attached photo. Raising the seat off the frame tabs with the thermoplastic shim had the spinoff benefit of creating a gap between the frame and the seat just under where I had back surgery with the positive effect that the seat has a considerable amount of flex there which I can feel when I hit a hard bump.

The final change I made was to remove the ventisit pad and go with a 3" Euromesh foam. Obviously after making all these positional changes I adjusted the boom and reach to the pedals.

I've done a couple of longer rides, most recently 53 miles with just under 3K feet of climbing with an average speed of 18.3 MPH.

So am I done tweaking? Doubtful but I will say I'm very happy with the setup now. I might go back to the 650b wheels (love that comfy ride!) but I'm enjoying the tubeless Conti's right now so maybe not.

 

[Frito Bandito]

It's great you got the bike how you like it Greg. Keep pedaling and racking up those miles. I never bothered to make 1 list with all the things I did to tweak mine to how it is now, but seeing your whole list here makes me realize we have to go to the shrink.

 

[cpml123]

Over the past several months I've made a number of changes to my S40 and I thought I'd share a few of them here. To recap the changes I've posted previously:

• I changed from the standard 17" chain stay to the 19"
• I moved from the 1X drivetrain to a SRAM GRX 11 speed with 50x34 chainrings and 11x40 cassette
• I switched from disc to rim brakes. As part of that switch, I took off the 650b wheels with 38mm tires and installed 700C Enve wheels (SES 4.5 with PowerTap hub front, SES 3.4 rear) with 32mm Continental GP5000's set up tubeless
  
• I installed a Thor Sport seat

I should also note that I had back surgery last August and was cleared to start riding again on 10 October. Since then, I've ridden just under 2000 miles total with 983 on the S40.

Overall, I was very happy with the function of the bike but not with the fit. I just wasn't comfortable and this limited how far I could ride. After 20-30 miles one of my neck, shoulders, butt, calf muscles hurt. Some of this was residual from the surgery (calf muscles specifically) as I also had numbness in my forefoot that would get worse the farther I rode.

So I've been working to resolve all these niggling fit issues and finally after a lot of tweaking I have to say it's now perfect. The biggest change I made was the position of the seat. My initial installation had the holes for the front frame tabs drilled 5.5 CM back from the lip of the seat. This resulted in a fair amount of my butt hanging off the front of the seat and the angle was such that I felt like I was sliding off.

I moved the seat considerably farther forward, the holes are now a little under 11 CM back from the lip. This made a huge difference - I'm now fully on the seat, it angles up slightly so there's no sensation of sliding off.

As part of moving the seat forward, I used the moldable thermoplastic that @tiltmaniac documented so well here. I made a shim only for the front of the seat, it's approximately 3 CM thick and covers both of the frame tabs. You can just see it in the attached photo. Raising the seat off the frame tabs with the thermoplastic shim had the spinoff benefit of creating a gap between the frame and the seat just under where I had back surgery with the positive effect that the seat has a considerable amount of flex there which I can feel when I hit a hard bump.

The final change I made was to remove the ventisit pad and go with a 3" Euromesh foam. Obviously after making all these positional changes I adjusted the boom and reach to the pedals.

I've done a couple of longer rides, most recently 53 miles with just under 3K feet of climbing with an average speed of 18.3 MPH.

So am I done tweaking? Doubtful but I will say I'm very happy with the setup now. I might go back to the 650b wheels (love that comfy ride!) but I'm enjoying the tubeless Conti's right now so maybe not.

View attachment 10730

What neck rest did you use?

 

[Greg S]

It's great you got the bike how you like it Greg. Keep pedaling and racking up those miles. I never bothered to make 1 list with all the things I did to tweak mine to how it is now, but seeing your whole list here makes me realize we have to go to the shrink.

Seriously! After posting I realized that the list of tweaks was woefully incomplete ;-)

I won’t air my dirty laundry here but suffice to say I’ve done a lot more. My friends refer to me as a “tweakaholic” (“Hi, I’m Greg and I’ve been clean for 3 seconds now”)

 

[Greg S]

What neck rest did you use?

The one on the Cruzbike store. This one.

 

[paco1961]

Is there really a CBer out there who is not a member of TCA (tweaking cyclists anonymous)?

 

[Frito Bandito]

If there is please let me know. He or she is either very lucky to get a perfect fit right out of the box or a weirdo.

 

[ak-tux]

Is there really a CBer out there who is not a member of TCA (tweaking cyclists anonymous)?

It applies to all bikes even uprights, unless it's used for very short distances. The difference with Cruzbike is the smaller user base and the lack of a widely tested and documented fit procedure.

For the S40, it's all about that seat, padding and the neckrest. Especially the bottom/lowest part of the seat and it's relation to the bottom bracket position. Short rides do not fully reveal the problems . Once you start doing longer rides exceeding 100 or 140Kms (60 or 80 miles) then you start noticing what needs to be tweaked.

 

[DocS]

Greg, I'm glad you're feeling better about it...
The Thor seat I used (I purchased it from a member of the forum) was the Easy gs.
It's a bit different than the Sport that I used on my Vendetta and is made for more up write seating. On the stock seat, I felt like I was sliding off. this seat kind of tilts up a bit.

I'm not a fan of the 1x11 drivetrain and will likely move to 2x10 or 2x11...

Blessings,
DocS (Rudy)

 

[3bs]

2x 10 ! n+1 !

 

[Frito Bandito]

I have a 2X11 105 setup and the lowest gear in back while on the 52 tooth front ring is making too much noise. I don't like cross chaining, but I'd rather keep my momentum going by keeping it on the big ring and just shift to lower gears as speed drops for a consistent slow down instead of dropping to the small chain ring 200m before the ascent and the tallest gear in back, then trying to accelerate again, losing momentum.

I have a Shimano Tiagra 4700 3X10 that is great for climbing and came off my V20 for that 105 groupset. The 4700 groupset will be going on my commuter bike by the end of the month, along with the trigger shifters I bought for it to replace the Brifters.

 

[Greg S]

I have a 2X11 105 setup and the lowest gear in back while on the 52 tooth front ring is making too much noise. I don't like cross chaining, but I'd rather keep my momentum going by keeping it on the big ring and just shift to lower gears as speed drops for a consistent slow down instead of dropping to the small chain ring 200m before the ascent and the tallest gear in back, then trying to accelerate again, losing momentum.

Yeah, this is the one real drawback to the 2X drivetrain - no matter how fast it shifts you're going to lose some momentum. I suspect that a Di2 based drivetrain would minimize it as it shifts pretty quickly and the front/rear Di2 derailleurs are so strong you can be going full gas while shifting - might be hard on the chain but the derailleurs would handle it (personal experience here).

The other thing that might help with Di2 is using "shift mode 2". For those who aren't familiar with Di2, it has three shifting modes you can select:

1. Mode 1 is normal Shimano road shifting, big and small levers do exactly what they do on a mechanical setup.
2. Mode 2 is called "semi-synchro" by Shimano. In this mode, when you change between chainrings it automatically shifts the cassette up or down a specified number of cogs (selectable in the E-Tube app) and it does it really quickly. This is the mode I run in my Di2 equipped bikes.
   
3. Mode 3 is "full synchro". In this mode you basically only use the small lever on the shifters and when you reach a point where you'd be crosschained it automatically shifts the front derailleur. I've tried this mode pretty extensively and concluded I just don't like it - no matter how much experience I had with it I was usually "surprised" when it shifted.

So I think a Di2 Cruzbike in mode 2 would minimize the loss of momentum as you approach a hill. A Di2 drivetrain might be in the future for my S40.

Yet another tweak!