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SIDI Astro Boots
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SIDI Astro Boots

The Sidi Nitro Boots are now known as the Sidi Astro! All the same great features with a new name.


  • Internal thermoplastic resin ankle ball protection cups.
  • Nylon inner sole with removable arch support pad.
  • 1.7mm thick Technomicro is used as a base material.
  • Lined with Teflon mesh on the ankle, Cambrelle on the toe and soft mesh on the tongue and gaiter area.
  • Partially vented upper.
  • Double stitched in all high stress areas.
  • Sidi’s own Tecno 3 wire entry and closure system.
  • Velcro strap above the instep area.
  • Toe shift pad.
  • Internal ankle padding.
  • Durable high grip sole.
  • Perforated details to improve ventilation.
  • Internal shock absorbing heel cup.
  • Reflective points above the heel.
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SIDI Astro Boots 4.6 5 8 8
Fits great, love the Tecno 3 wire entry and closure system. Wore for a couple months, haven't had any fitting/break in issues. I wear a 9 and ordered Euro 43. The only problem I had was getting caught in some rain and having wet feet. These boots are not anyway waterproof. Boots keep your feet cool on warm days, you may want to wear warmer socks for the cooler days. October 31, 2014
Really good summer boots I normally wear a wide/E width, but these fit well. I figured out that you need to get your heel back and the crank lace system makes that easy. I found that I needed to wear thinner socks. The footbed isn't well padded and I found that uncomfortable after standing for a couple of hours. I wore them for a whole day when I first got them and they seem to breaking in well. I like the narrow sole on the bike. The lacing system is the best feature. They're a bit ugly, but overall I really like these boots. Protection looks good. August 3, 2014
A Decent Warm-weather Low Boot I have had numerous Sidi boots and shoes in the past, and was not disappointed with the Astro. The quality is top notch, as always, and I expect them to last a long time. They do seem to run a bit large, and the tongues migrate to the outside of the shoe while I wear them, something I will try to mitigate somehow. May 15, 2014
Moto Guzzi V7 Rider. This boot is very comfortable, and is OK to walk around in. I love the lace system, works very efficiently. It also offers good sensitivity on the controls. Just what I was looking for. March 31, 2014
Finally found my boot! Wearing a size 14 makes it extra difficult to find nice motorcycle boots. In addition, I wanted something that I could wear all day even when not riding. Although these boots show that they only come in size 48 (13-13.5 US), the wonderful Rep at Revzilla told me they do run a little large but also slightly narrow. So I took a chance and ordered them. Well, i could not be more pleased with the fit, style and quality. And an added bonus is that these boots are completely Vegan, so I can feel good about making a sound ethical purchase as well. June 18, 2013
Great everyday riding shoe I have big, wide feet, so finding shoes/boots that fit and had the style I'm looking for can be a challenge... I have consistently found Sidi to be about the only brand that works reliably for me! I was looking for an everyday riding shoe with reasonable technical features, but comfortable and stylish enough to wear around all day in a semi casual office environment, or on the weekend with jeans, and are easy to get in and out of. So far, the Nitro has ticked every box! They have only taken a couple of days to get comfy, and while they're a touch on the narrow side, the Techno 3 system makes it super easy to let out a little slack. My other Sidi boots have been super comfy once they're worn in, and these feel like they'll do the same. They are easy to walk around in, and fine for all day wear, and while they are obviously a riding shoe, they certainly don't look too out of place in the office, and are not too bulky under regular trousers or jeans. On the bike, they feel just right. The shift pad is perfectly placed, and the sole feels just firm enough. The venting looks minimal, but I was surprised how much cool air I could feel when it was a little brisk in the morning, so I suspect these are going to be more suited to the warmer months , and may not be so suited to the cooler months. All in all, I'm very happy with my choice. Regarding the shipping process, I ordered them on the Saturday, and they arrived on Tuesday, even though the website said it would take 3-4 days before they'd ship, so I'm super happy with the Revzilla service! May 16, 2013
Very satisfied with this purchase Received the next day, thank you RevZilla! I wear a US size 11, European 45. The fit is spot on for me and break-in is about there after wearing them 6 times (15 hours riding, 2 hours walking). The fit will be snug if your foot is a bit on the wide side. The boots are lightweight, comfortable, and on/off is a snap. The closure system works well but I cannot comment its reliability yet. I really like that there are no strings to get caught in the controls. The Velcro strap is functional too. Ventilation is adequate. The sole works well walking in dry/wet conditions and provides adequate support for some standing on the foot pegs. The shift pad is correctly located for me. Bang for the buck cannot get 5/5 in my opinion because $215 is expensive. Protection & Durability would have been scored differently had the two categories been separate. The protection is as advertised so it should be rated as such (5/5 IMHO). You get the protection you bought… I cannot rate durability yet because I have not tested them long enough. We’ll see how they are holding up at the end of the season with 12k+ miles on em. The Style would've gotten a better rating but everyone in my family said the boots are ugly. I disagree. This is a purpose-built shoe/boot with technical features that influence the look. Sidi did a reasonable job with esthetics. Side note: I also have a pair of Sidi Adventure GT boots. Both Sidi products were accurately reviewed by RevZilla. I am a Sidi fan and it is my opinion you can’t go wrong with RevZilla. April 15, 2013
Great shoes for in metro riding! I got these shoes faster that I expected from Revzilla... THANKS!!! This was a very smooth purchase. These shoes are nice! They fit me perfect. I little still at top and will require some breaking in, but better than I expected. These shoes will be great for roaming around town on my Ducati Diavel. March 20, 2013
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Have a functionality, fit, or otherwise product-specific question about the SIDI Astro Boots? Ask it here! If you have a customer service or shipping question, please direct it to our Customer Service department.

SIDI Astro Boots
Already Asked: 2 Questions, 7 Answers
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RevZilla Store asked: Why did you choose this?
mick e: No animal body parts and they have good reviews for comfort and protection Oct 9, 2014
Vinton K: Style Sep 14, 2014
Benjamin H: Price and features of this model. Picking SIDI was a no-brainer. I been a competitive triathlete and cyclist for over 25 years. SIDI makes the BEST cycling and triathlon bike shoes. Apr 29, 2014
A shopper asked: The SIDI size chart indicates EURO 44 for US Men’s 9.5 to 10 and 45 for US 10.5-11.
My size is US 10.5. Should I order EURO 44 or 45?
Apr 16, 2014
Answer this · Send to friends Good question? Yes (1) No (0)
Scott K: I would go with the Euro 45s. I have 10-1/2 to 11 size feet, and the 45's are about right for me; a little snug in the toe box, but nothing that stops a full day's ride. Of equal importance—to me at least—is that the ankle shaft is large enough that they're not too hard to get off at the end of a long day's ride. Apr 26, 2014
Reply to Scott Good answer? Yes (0) No (0)
Gregorio B: My shoe size is 9.5, and I have the adventure goretex, the sidi rain and the astro boots, all of the inside say US 9.5 / EUR 43. I would choose the EUR 45. for a 10.5 US size. The Tour rain I bought were a little thight, but now after some time using them the fit just fine. hope this helps Apr 25, 2014
Reply to Gregorio Good answer? Yes (0) No (0)
Isaac G: I would order 45 as I don't like my boots to be tight in any way--either way, should the 45 prove to be too large, Revzilla is awesome at exchanging :). Apr 25, 2014
Reply to Isaac Good answer? Yes (0) No (0)
Bryon K: I don't have your feet........ but my US size is 10 and I ordered size 43 and they fit me perfectly. Apr 25, 2014
Reply to Bryon Good answer? Yes (0) No (0)
Product Style RevZilla Item # Manufacturer Product # Availability
Black / 7.5/41 864537 SIT-NIT-BKBK-41 Available: Requires 2-4 business days processing time prior to shipment.
Black / 8.5/42 864538 SIT-NIT-BKBK-42 In Stock: Ships within 24 hours
Black / 9.5/43 864539 SIT-NIT-BKBK-43 Available: Requires 2-4 business days processing time prior to shipment.
Black / 10/44 864540 SIT-NIT-BKBK-44 In Stock: Ships within 24 hours
Black / 11/45 864541 SIT-NIT-BKBK-45 In Stock: Ships within 24 hours
Black / 11.5/46 864542 SIT-NIT-BKBK-46 In Stock: Ships within 24 hours
Black / 12.5/47 864543 SIT-NIT-BKBK-47 In Stock: Ships within 24 hours
Black / 13/48 864544 SIT-NIT-BKBK-48 Out of Stock