Ask the experts

[SchralphMacchio]

Well, I sent the Stumpy Expert T Type to said friend’s husband. He told me her birthday is in two weeks and just immediately ordered it outright!

Thanks for the PSA head’s up!

More friends with bikes who also have kids in similar ages to ours also means more friends to watch the kids while the dads all do a lap together!

[Phall]

That specialized deal is matchable at Specialized Owned brick and mortar shops, even if inventory isn't showing on S website. Almost bought that t-type but dont think I can ride a 34.

[Dromond]

Correct. Although not a ton lower. To put a number on it, 30x50 is 17.4 gear inches. 32x52 is 17.8.

(That's with a 29" wheel, although it's still a .4 gear inch difference with a 27.5, it's just a lower number for both gear ratios).

The only real argument for the 32t ring is that most suspensions are designed around a 32t. So going down to a 30t is going to affect the bike's anti squat and pedal kickback. Entirely questionable whether that's at all noticeable though. Probably varies a bit from bike to bike.

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I’m getting a lot of chain noise on descents that I think is from pedal kickback. It happens I think in 7th gear and above. It came with a 32t ring but I put a 30 on it….. hmmmm

[jono]

Pedal kickback is a little more complicated than just a suspension curve if you don't have infinite teeth in the freewheel. I'd be hard pressed to consider that as a factor for chainring selection.

Assuming your feet are stationary, the pawls have to catch up in order to start "kicking back." The faster you're going the less likely that is (likely because there's always the random factor of where the pawl was when you hit the bump). And big plates in back pull more chain. So if you're getting more in higher gears there might be another cause to look into.

[east or bust]

Pedal kickback is a little more complicated than just a suspension curve if you don't have infinite teeth in the freewheel. I'd be hard pressed to consider that as a factor for chainring selection.

Assuming your feet are stationary, the pawls have to catch up in order to start "kicking back." The faster you're going the less likely that is (likely because there's always the random factor of where the pawl was when you hit the bump). And big plates in back pull more chain. So if you're getting more in higher gears there might be another cause to look into.

I’d think the faster you’re going the more likely you’re on the brakes in the bumps, so the relative rotational speed of the wheel/hub could be anywhere between how fast you’re actually going and 0.

eta: I guess where I’m going with that thought is that braking is also a major factor in kickback.

[jono]

Sometimes, sure. Which is kind of my biggest reason for discounting it as a factor compared to other things--particularly getting the gear ratios you want.

Not to say kickback can't play havoc with suspension performance, but the impact of a 4 mm change to the chain's tangency point up front is probably hard to notice on most bikes.

[toast2266]

I’m getting a lot of chain noise on descents that I think is from pedal kickback. It happens I think in 7th gear and above. It came with a 32t ring but I put a 30 on it….. hmmmm

I'd be pretty surprised if a change in pedal kickback had anything to do with your chain noise. But going to a slightly smaller ring might mean your chain is a little too long now, which would be noisier. Could also just be that your derailleur clutch is getting tired and the chain is bouncing around more.

Also, agreed with Jono that for most people on most bikes, changes in anti squat / kickback shouldn't be a factor at all in chainring selection. It's a relatively small change in a kinematic trait that is relatively subtle to begin with. But it's still winter and we're bored, so obviously it's worth discussing in detail.



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[jono]

Exactly. 7th gear and above also points to the problem showing up more with less chain tension and more chain weight to control with less leverage.

And anti-squat can be tweaked with a little ride height change, too, since it varies with the height of your center of mass. Sag settings > chainring diameter.

[Andeh]

Smaller chainring will have on average 1 less tooth of engagement and the corresponding chain retention (going from 32-30) as well.

[jono]

And it'll be lighter.

[Dromond]

I’ve adjusted the chain length so it should be right, but you never know. I’ve also rebuilt and adjusted the clutch (Shimano) a lot. Even when it is really stiff I will get the noise. The hub (cheaper Stans) has a fairly low number of engagement points so that’s the most likely contributor I think. I’ve done experiments where I do a fast hit and I can hear the hub noise. I think the rotational speed is causing it to engage. I hadn’t thought of playing with sag to see how to affects it, so I can experiment with that. One reason I thought a slightly larger chainring might help is I would tend to be down one more gear on descents, making it less likely to be over that problem gear. That still seems like a weird trade off since I’m nowhere near the top gear, and the purpose of the gears is descending

[jono]

There are a bunch of things in there that seem like you're thinking of pedal kickback, well, backwards. Less POE would (often) help reduce pedal kickback, for example. Because that allows the rear wheel to rotate further before encountering chain resistance.

Can you get one less chain link to still work with 1st gear? That might be a worthwhile experiment.

[toast2266]

One reason I thought a slightly larger chainring might help is I would tend to be down one more gear on descents, making it less likely to be over that problem gear. That still seems like a weird trade off since I’m nowhere near the top gear, and the purpose of the gears is descending

Being in a harder gear / smaller cog will definitely make the chain slap more. Partly because the chain has less tension in smaller cogs. And partly because the chain is further outboard on the bike, and therefore closer to the chainstay.

But that is a somewhat inescapable reality. Covering the ass end of your bike in mastic tape is going to be more effective at combating that than messing around with chainring sizes.

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[jackstraw]

I don't hear shit going down as I'm so focused on trying to stay on my line and upright. [emoji16]

[XXX-er]

But that is a somewhat inescapable reality. Covering the ass end of your bike in mastic tape is going to be more effective at combating that than messing around with chainring sizes.



a thing of the past with both the SC and Yeti product IME they have large molded rubber pieces wrapping around the swingarm

[jackstraw]

But that is a somewhat inescapable reality. Covering the ass end of your bike in mastic tape is going to be more effective at combating that than messing around with chainring sizes.



a thing of the past with both the SC and Yeti product IME they have large molded rubber pieces wrapping around the swingarm

Yeah they do.

[XXX-er]

well i no longer have to turn down my hearing aid !

[Sandbox]

Can most ( or all) newer Fox 36 be converted to 140mm with a new air shaft?


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[MegaStoke]

I’ve really been struggling with bike shoes lately, and need new ones, both clippers and flat.

My feet are quite wide at the metatarsals, with a prominent knob at the 5th metatarsal head. Then the rest of my foot is low volume, low instep, narrow heel, and skinny lower leg.

It seems like anything I try that is wide enough to accommodate my forefoot is always super insecure and sloppy throughout the rest of the shoe.

What shoes should I be trying out?

[climberevan]

I’ve really been struggling with bike shoes lately, and need new ones, both clippers and flat.

My feet are quite wide at the metatarsals, with a prominent knob at the 5th metatarsal head. Then the rest of my foot is low volume, low instep, narrow heel, and skinny lower leg.

It seems like anything I try that is wide enough to accommodate my forefoot is always super insecure and sloppy throughout the rest of the shoe.

What shoes should I be trying out?

Lake. The regular ones are around 3-5 mm wider than the common brands at the forefoot. Their "wide" one is even wider. The rest of the shoe is normal volume. I have the same situation as you and Lakes are the answer.

Bonus: they are super high performance and last forever. They regularly have sales for 50% off. If ordering direct from their site, use the sizing guide and be aware that they will charge a restock fee on returns. As great as the shoes are, Lake USA service is pretty terrible.

[XXX-er]

I’ve really been struggling with bike shoes lately, and need new ones, both clippers and flat. My feet are quite wide at the metatarsals, with a prominent knob at the 5th metatarsal head. Then the rest of my foot is low volume, low instep, narrow heel, and skinny lower leg. It seems like anything I try that is wide enough to accommodate my forefoot is always super insecure and sloppy throughout the rest of the shoe. What shoes should I be trying out?






For clipless NOT Shimano I have given away 2 pair , I suggest hold your nose and walk into a Specialized store which IME fit wide in front and narrow thru the heel




5/10's with an extra shim are working for flats

[Andeh]

I have collapsed arches, so basically not very high instep but as wide or wider past the met heads. Heels are pretty skinny. Five Ten Impact Pro is my go-to flat pedal shoe, and I've tried nearly every recent flat. I think part of why it works for me is that the outsole is pretty wide so it supports the full width of my foot pretty well, without pressure points on the edges. The interior is moderately padded, so I can get a snug fit without being tight or sliding around. There are other flats that are roomier in the toe (like Freerider Pro or Fox Union) but I end up having to crank the laces tighter to stop from sliding forward. Don't even try the RC Tallac, it has massive volume in the mid, very low toebox. The Shimano flats are pretty comfy too but the rubber grip is meh at best, and the midsole is too soft for me for aggressive riding.

[SchralphMacchio]

Related, one thing I may experiment with is moving my customer molded ski boot insoles into my MTB shoes for the summer and seeing how that goes. They are cut for a smaller liner fit than my bike shoes, but hopefully they stay in place without sliding around.
Anyone ever tried this?

[toast2266]

Related, one thing I may experiment with is moving my customer molded ski boot insoles into my MTB shoes for the summer and seeing how that goes. They are cut for a smaller liner fit than my bike shoes, but hopefully they stay in place without sliding around.
Anyone ever tried this?

My wife does that. Seems to work well for her. Her feet are all fucked up so she needs the support.

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[Huskier]

Gravel/road weanie question: I've fully embraced Dad bod and picked up a Turbo Creo 2. Tires are Tracer pro's in 42. They feel super, super slow. Molasses compared to my GP5000's. But the interwebs have their rolling resistance at like 15 watts. The GP5000's sit at 14. How is that possible? A fully treaded gravel tire that rolls the same as a road slick? I feel like I'm being gaslit by the big S.... Which got me thinking: Has anyone successfully cobbled together a garage dynamometer for the purposes of testing tires, drivetrain losses, etc?

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